MySQL 5.6 Release Notes

Abstract

This document contains release notes for the changes in each release of MySQL 5.6, up through MySQL 5.6.51. For

information about changes in a different MySQL series, see the release notes for that series.

Note. MySQL 5.6.51 is the last release of the MySQL 5.6 series.

For additional MySQL 5.6 documentation, see the MySQL 5.6 Reference Manual, which includes an overview of

features added in MySQL 5.6 (What Is New in MySQL 5.6), and discussion of upgrade issues that you may encounter

for upgrades from MySQL 5.5 to MySQL 5.6 (Changes in MySQL 5.6).

MySQL platform support evolves over time; please refer to https://www.mysql.com/support/supportedplatforms/

database.html for the latest updates.

Updates to these notes occur as new product features are added, so that everybody can follow the development

process. If a recent version is listed here that you cannot find on the download page (https://dev.mysql.com/

downloads/), the version has not yet been released.

The documentation included in source and binary distributions may not be fully up to date with respect to release note

entries because integration of the documentation occurs at release build time. For the most up-to-date release notes,

please refer to the online documentation instead.

For legal information, see the Legal Notices.

For help with using MySQL, please visit the MySQL Forums, where you can discuss your issues with other MySQL

users.

Document generated on: 2023-02-24 (revision: 26185)

Table of Contents

Preface and Legal Notices ................................................................................................................. 2

Changes in MySQL 5.6.51 (2021-01-20, General Availability) ............................................................... 4

Changes in MySQL 5.6.50 (2020-10-19, General Availability) ............................................................... 4

Changes in MySQL 5.6.49 (2020-07-13, General Availability) ............................................................... 5

Changes in MySQL 5.6.48 (2020-04-27, General Availability) ............................................................... 6

Changes in MySQL 5.6.47 (2020-01-13, General Availability) ............................................................... 7

Changes in MySQL 5.6.46 (2019-10-14, General Availability) ............................................................... 7

Changes in MySQL 5.6.45 (2019-07-22, General Availability) ............................................................... 8

Changes in MySQL 5.6.44 (2019-04-25, General Availability) ............................................................... 9

Changes in MySQL 5.6.43 (2019-01-21, General Availability) ............................................................. 11

Changes in MySQL 5.6.42 (2018-10-22, General Availability) ............................................................. 12

Changes in MySQL 5.6.41 (2018-07-27, General Availability) ............................................................. 13

Changes in MySQL 5.6.40 (2018-04-19, General Availability) ............................................................. 15

Changes in MySQL 5.6.39 (2018-01-15, General Availability) ............................................................. 17

Changes in MySQL 5.6.38 (2017-10-16, General Availability) ............................................................. 19

Changes in MySQL 5.6.37 (2017-07-17, General Availability) ............................................................. 20

Changes in MySQL 5.6.36 (2017-04-10, General Availability) ............................................................. 22

Changes in MySQL 5.6.35 (2016-12-12, General Availability) ............................................................. 27

Changes in MySQL 5.6.34 (2016-10-12, General Availability) ............................................................. 31

Changes in MySQL 5.6.33 (2016-09-06, General Availability) ............................................................. 31

Changes in MySQL 5.6.32 (2016-07-29, General Availability) ............................................................. 33

MySQL 5.6 Release Notes

Changes in MySQL 5.6.31 (2016-06-02, General Availability) ............................................................. 35

Changes in MySQL 5.6.30 (2016-04-11, General Availability) ............................................................. 37

Changes in MySQL 5.6.29 (2016-02-05, General Availability) ............................................................. 40

Changes in MySQL 5.6.28 (2015-12-07, General Availability) ............................................................. 44

Changes in MySQL 5.6.27 (2015-09-30, General Availability) ............................................................. 46

Changes in MySQL 5.6.26 (2015-07-24, General Availability) ............................................................. 50

Changes in MySQL 5.6.25 (2015-05-29, General Availability) ............................................................. 54

Changes in MySQL 5.6.24 (2015-04-06, General Availability) ............................................................. 58

Changes in MySQL 5.6.23 (2015-02-02, General Availability) ............................................................. 63

Changes in MySQL 5.6.22 (2014-12-01, General Availability) ............................................................. 66

Changes in MySQL 5.6.21 (2014-09-23, General Availability) ............................................................. 70

Changes in MySQL 5.6.20 (2014-07-31, General Availability) ............................................................. 75

Changes in MySQL 5.6.19 (2014-05-30, General Availability) ............................................................. 82

Changes in MySQL 5.6.18 (2014-04-11, General Availability) ............................................................. 85

Changes in MySQL 5.6.17 (2014-03-27, General Availability) ............................................................. 86

Changes in MySQL 5.6.16 (2014-01-31, General Availability) ............................................................. 92

Changes in MySQL 5.6.15 (2013-12-03, General Availability) ............................................................. 98

Changes in MySQL 5.6.14 (2013-09-20, General Availability) ........................................................... 105

Changes in MySQL 5.6.13 (2013-07-31, General Availability) ........................................................... 111

Changes in MySQL 5.6.12 (2013-06-03, General Availability) ........................................................... 120

Changes in MySQL 5.6.11 (2013-04-18, General Availability) ........................................................... 131

Changes in MySQL 5.6.10 (2013-02-05, General Availability) ........................................................... 147

Changes in MySQL 5.6.9 (2012-12-11, Release Candidate) ............................................................. 157

Changes in MySQL 5.6.8 (2012-11-07, Release Candidate) ............................................................. 166

Changes in MySQL 5.6.7 (2012-09-29, Release Candidate) ............................................................. 176

Changes in MySQL 5.6.6 (2012-08-07, Milestone 9) ........................................................................ 191

Changes in MySQL 5.6.5 (2012-04-10, Milestone 8) ........................................................................ 214

Changes in MySQL 5.6.4 (2011-12-20, Milestone 7) ........................................................................ 230

Changes in MySQL 5.6.3 (2011-10-03, Milestone 6) ........................................................................ 243

Changes in MySQL 5.6.2 (2011-04-11, Developer Milestone) ........................................................... 265

Changes in MySQL 5.6.1 (Not released, Milestone 5) ...................................................................... 278

Changes in MySQL 5.6.0 (Not released, Milestone 4) ...................................................................... 288

Index .............................................................................................................................................. 292

Preface and Legal Notices

This document contains release notes for the changes in each release of MySQL 5.6, up through MySQL

5.6.51.

Legal Notices

This software and related documentation are provided under a license agreement containing restrictions

on use and disclosure and are protected by intellectual property laws. Except as expressly permitted

in your license agreement or allowed by law, you may not use, copy, reproduce, translate, broadcast,

modify, license, transmit, distribute, exhibit, perform, publish, or display any part, in any form, or by any

means. Reverse engineering, disassembly, or decompilation of this software, unless required by law for

interoperability, is prohibited.

The information contained herein is subject to change without notice and is not warranted to be error-free.

If you find any errors, please report them to us in writing.

If this is software or related documentation that is delivered to the U.S. Government or anyone licensing it

on behalf of the U.S. Government, then the following notice is applicable:

MySQL 5.6 Release Notes

U.S. GOVERNMENT END USERS: Oracle programs (including any operating system, integrated

software, any programs embedded, installed or activated on delivered hardware, and modifications of

such programs) and Oracle computer documentation or other Oracle data delivered to or accessed by

U.S. Government end users are "commercial computer software" or "commercial computer software

documentation" pursuant to the applicable Federal Acquisition Regulation and agency-specific

supplemental regulations. As such, the use, reproduction, duplication, release, display, disclosure,

modification, preparation of derivative works, and/or adaptation of i) Oracle programs (including any

operating system, integrated software, any programs embedded, installed or activated on delivered

hardware, and modifications of such programs), ii) Oracle computer documentation and/or iii) other Oracle

data, is subject to the rights and limitations specified in the license contained in the applicable contract.

The terms governing the U.S. Government's use of Oracle cloud services are defined by the applicable

contract for such services. No other rights are granted to the U.S. Government.

This software or hardware is developed for general use in a variety of information management

applications. It is not developed or intended for use in any inherently dangerous applications, including

applications that may create a risk of personal injury. If you use this software or hardware in dangerous

applications, then you shall be responsible to take all appropriate fail-safe, backup, redundancy, and other

measures to ensure its safe use. Oracle Corporation and its affiliates disclaim any liability for any damages

caused by use of this software or hardware in dangerous applications.

Oracle, Java, and MySQL are registered trademarks of Oracle and/or its affiliates. Other names may be

trademarks of their respective owners.

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This software or hardware and documentation may provide access to or information about content,

products, and services from third parties. Oracle Corporation and its affiliates are not responsible for and

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unless otherwise set forth in an applicable agreement between you and Oracle. Oracle Corporation and its

affiliates will not be responsible for any loss, costs, or damages incurred due to your access to or use of

third-party content, products, or services, except as set forth in an applicable agreement between you and

Oracle.

This documentation is NOT distributed under a GPL license. Use of this documentation is subject to the

following terms:

You may create a printed copy of this documentation solely for your own personal use. Conversion to other

formats is allowed as long as the actual content is not altered or edited in any way. You shall not publish

or distribute this documentation in any form or on any media, except if you distribute the documentation in

a manner similar to how Oracle disseminates it (that is, electronically for download on a Web site with the

software) or on a CD-ROM or similar medium, provided however that the documentation is disseminated

together with the software on the same medium. Any other use, such as any dissemination of printed

copies or use of this documentation, in whole or in part, in another publication, requires the prior written

consent from an authorized representative of Oracle. Oracle and/or its affiliates reserve any and all rights

to this documentation not expressly granted above.

Documentation Accessibility

For information about Oracle's commitment to accessibility, visit the Oracle Accessibility Program website

https://www.oracle.com/corporate/accessibility/.

MySQL 5.6 Release Notes

Access to Oracle Support for Accessibility

Oracle customers that have purchased support have access to electronic support through My Oracle

Support. For information, visit

https://www.oracle.com/corporate/accessibility/learning-support.html#support-tab.

Changes in MySQL 5.6.51 (2021-01-20, General Availability)

Note

MySQL 5.6.51 is the last release of the MySQL 5.6 series.

• Security Notes

• Bugs Fixed

Security Notes

• The linked OpenSSL library for MySQL Server has been updated to version 1.1.1i. Issues fixed

in the new OpenSSL version are described at https://www.openssl.org/news/cl111.txt and https://

www.openssl.org/news/vulnerabilities.html. (Bug #32260610)

Bugs Fixed

• InnoDB: The full-text search synchronization thread attempted to read a previously-freed word from the

index cache. (Bug #31310404)

• The server did not handle all cases of the WHERE_CONDITION optimization correctly. (Bug #31905199)

• Privileges for some INFORMATION_SCHEMA tables were checked incorrectly. (Bug #31553323)

• In certain cases, the server did not handle multiply-nested subqueries correctly. (Bug #31472704)

• A buffer overflow in the client library was fixed. (Bug #30885987)

Changes in MySQL 5.6.50 (2020-10-19, General Availability)

• Functionality Added or Changed

• Bugs Fixed

Functionality Added or Changed

• LOCK TABLES privilege checking for views was improved. (Bug #31304432, WL #14092)

Bugs Fixed

• InnoDB: In session started with START TRANSACTION WITH CONSISTENT SNAPSHOT, a range query

returned a truncated result. The end range flag was not reset at the beginning of the index read resulting

in an aborted read and missing rows. (Bug #30950714, Bug #98642)

References: This issue is a regression of: Bug #23481444.

• In bootstrapping mode, certain multiple-statement transactions could cause unexpected server behavior.

(Bug #31650096)

MySQL 5.6 Release Notes

• Assigning CONCAT('') or CONCAT_WS('') to a variable set the variable to NULL, not the empty string.

(Bug #31320716, Bug #99485, Bug #31413167, Bug #99722)

• ORDER BY queries were not executed correctly when sort_buffer_size and max_sort_length

were set to values which caused the internal limit on the maximum number of keys allowed per sort

buffer to be set to 0. (Bug #30175483)

• The internal method Field_tiny::pack() did not always perform bounds checking as expected.

(Bug #29948029)

References: See also: Bug #31591391.

• A large number of nested arguments in full-text search query caused an error. (Bug #29929684)

• An assertion could be raised when the SQL layer passed incorrect information to InnoDB about the type

of operation to be performed on a temporary table. (Bug #22503696)

Changes in MySQL 5.6.49 (2020-07-13, General Availability)

• Configuration Notes

• Security Notes

• Bugs Fixed

Configuration Notes

• tcmalloc is no longer a permitted value for the mysqld_safe --malloc-lib option. (Bug

#31372027)

Security Notes

• Incompatible Change: Access to the INFORMATION_SCHEMA.FILES table now requires the PROCESS

privilege.

This change affects users of the mysqldump command, which accesses tablespace information in the

FILES table, and thus now requires the PROCESS privilege as well. Users who do not need to dump

tablespace information can work around this requirement by invoking mysqldump with the --no-

tablespaces option. (Bug #30350829)

• The linked OpenSSL library for MySQL Server has been updated to version 1.1.1g. Issues fixed

in the new OpenSSL version are described at https://www.openssl.org/news/cl111.txt and https://

www.openssl.org/news/vulnerabilities.html. (Bug #31296697)

Bugs Fixed

• Partitioning: A query against a partitioned table, which used an ORDER BY, returned unordered results

under the following conditions:

• The table had a composite index with a prefix on one of the columns.

• The query's WHERE clause contained an equality condition on the prefixed column.

• The column with the prefix was the leftmost column in the index.

• The column used in the ORDER BY was the rightmost column in the index.

MySQL 5.6 Release Notes

• The index was used for handling the ORDER BY.

Our thanks to Quanan Han for the suggestion. (Bug #84070, Bug #25207522)

• Replication: When a replication source server shuts down and restarts, its MEMORY tables become

empty. To replicate this effect to replicas, the first time that the source uses a given MEMORY table after

startup, it notifies replicas that the table must be emptied by writing a DELETE statement for that table

to the binary log. Previously, the generated DELETE statement was written to the binary log statement

cache for the current session, which could result in it being logged together with other statements

under the same GTID, or logged without BEGIN and COMMIT statements. Also, in some situations, the

generated DELETE statement could consume the GTID intended for the transaction that triggered it. The

generated DELETE statement is now logged with accompanying BEGIN and COMMIT statements, and the

resulting transaction is flushed to the binary log immediately after it is written to the statement cache, so

that it always receives its own GTID and is kept separate from other transactions. (Bug #30527929, Bug

#25681518, Bug #77729)

• mysql_store_result() could fail to detect invalid data packets. (Bug #29921423)

• The server sometimes mistakenly removed a subquery with a GROUP BY when optimizing a query, even

in some cases when this subquery was used by an outer select. This could occur when the subquery

also used an aggregate function. (Bug #28240054)

Changes in MySQL 5.6.48 (2020-04-27, General Availability)

Bugs Fixed

• InnoDB: A tablespace import operation that failed due to the source and destination tables being defined

with different DATA DIRECTORY clauses reported an insufficiently descriptive schema mismatch error.

Moreover, if a .cfg file was not present, the same operation would raise an assertion failure. A more

informative error message is now reported in both cases before the import operation is terminated due to

the data directory mismatch. (Bug #30190199, Bug #30190227, Bug #20644698, Bug #76142)

• InnoDB: Updating certain InnoDB system variables that take string values raised invalid read errors

during Valgrind testing. (Bug #29717909, Bug #95215)

• Replication: In the event of an unplanned disconnection of a replication slave from the master, the

reference to the master's dump thread might not be removed from the list of registered slaves, in

which case statements that accessed the list of slaves would fail. The issue has now been fixed. (Bug

#29915479)

• Replication: With the settings binlog_format=MIXED, tx_isolation=READ-COMMITTED, and

binlog_row_image=FULL, an INSERT ... SELECT query involving a transactional storage engine

omitted any columns with a null value from the row image written to the binary log. This happened

because when processing INSERT ... SELECT statements, the columns were marked for inserts

before the binary logging format was selected. The issue has now been fixed. (Bug #29110804, Bug

#93423)

• The Event Scheduler had a memory leak. (Bug #30628268)

• Under certain circumstances, a memcached command could result in reading an uninitialized memory

buffer, causing a failure. (Bug #30592346)

• CONCAT() and CONCAT_WS() could produce incorrect results in rare cases due to incorrect substring

handling. (Bug #30350206, Bug #96950)

• Scheduling of events could be disturbed by removing events. (Bug #30301356, Bug #96849)

MySQL 5.6 Release Notes

• Client programs could load authentication plugins from outside the plugin library. (Bug #30191834, Bug

#30644258)

• A query with a WHERE clause whose predicate contained a numeric value in scientific notation was not

handled correctly.

In addition, attempting to insert a particular integer specified as a string caused a server exit when the

string-to-integer conversion was not successful. (Bug #29723340, Bug #30441969)

• The client library could dereference a null pointer while fetching result set metadata from the server.

(Bug #29597896, Bug #30689251)

Changes in MySQL 5.6.47 (2020-01-13, General Availability)

Bugs Fixed

• Replication: Under certain conditions, replication of conditional comments could fail. (Bug #28388217)

• Replication: When GTIDs are enabled on a replication master and slave, and the slave connects to

the master with the MASTER_AUTO_POSITION=1 option set, the master must send the slave all the

transactions that the slave has not already received, committed, or both. If any of the transactions that

should be sent by the master have been already purged from the master's binary log, the master sends

the error ER_MASTER_HAS_PURGED_REQUIRED_GTIDS (1789) to the slave, and replication does not

start.

The message provided for the error ER_MASTER_HAS_PURGED_REQUIRED_GTIDS has been changed

to provide advice on the correct action in this situation, which is for the slave to replicate the missing

transactions from another source, or for the slave to be replaced by a new slave created from a more

recent backup. The message advises that the master's binary log expiration period can be revised to

avoid the situation in future. In addition, the master now identifies the GTIDs of the purged transactions

and supplies them in its error log in the warning message ER_FOUND_MISSING_GTIDS (11809), so that

you do not need to calculate the missing GTIDs manually. (Bug #26004541, Bug #29769293)

• With multiple sessions executing concurrent INSERT ... ON DUPLICATE KEY UPDATE statements

into a table with an AUTO_INCREMENT column but not specifying the AUTO_INCREMENT value, inserts

could fail with a unique index violation. (Bug #30194841, Bug #96578)

• A SELECT using a WHERE condition of the form A AND (B OR C [OR ...]) resulting in an impossible

range led to an unplanned exit of the server. (Bug #29770705)

• An incomplete connection packet could cause clients not to properly initialize the authentication plugin

name. (Bug #29630767)

Changes in MySQL 5.6.46 (2019-10-14, General Availability)

• Configuration Notes

• Security Notes

• Bugs Fixed

Configuration Notes

• It is now possible to compile MySQL 5.6 using OpenSSL 1.1.1, enabling compilation support for MySQL

5.6 against OpenSSL even when OpenSSL 1.0.2 reaches End of Life status at the end of 2019.

MySQL 5.6 Release Notes

In addition, MySQL 5.6 now supports TLSv1.1 and TLSv1.2 protocols for encrypted connections. This

applies to MySQL Server, MySQL clients such as mysql and mysqldump, and master/slave replication.

Previously, MySQL 5.6 supported only TLSv1, so TLSv1.1/TLSv1.2 support enables use of more secure

TLS protocols. It also enables connecting from MySQL 5.6 clients and replication slaves to MySQL 5.7

and higher servers that have TLSv1 disabled, which previously was not possible. It also means that

MySQL 5.7 and higher clients that do not want to use TLSv1 can connect to MySQL 5.6 servers. (WL

#12903)

• All MySQL 5.6 builds now use OpenSSL. MySQL no longer supports using yaSSL as the SSL library,

and source distributions no longer include yaSSL.

The WITH_SSL CMake option no longer permits bundled (use yaSSL) as a valid value, and the default

option value has changed from bundled to system (use the version of OpenSSL installed on the host

system). (WL #13289)

Security Notes

• The linked OpenSSL library for MySQL Server has been updated to version 1.1.1c. Issues fixed

in the new OpenSSL version are described at https://www.openssl.org/news/cl111.txt and https://

www.openssl.org/news/vulnerabilities.html. (Bug #29868818)

Bugs Fixed

• Improper locking during storage engine initialization could cause a server exit. (Bug #29782379)

• VS2019 produced compilation errors with debug compilation selected due to use of the /ZI flag. Now /

Z7 is used instead. (Bug #29691691, Bug #95125)

• For MySQL Community Edition, the cipher order specified by the client was used in preference to the

order on the server side, unless the server was configured with an explicit ssl_cipher order. (Bug

#26882825)

• Password masking was incomplete for SHOW PROCESSLIST and some INFORMATION_SCHEMA and

Performance Schema tables. (Bug #20712046)

• The -DWITH_EXAMPLE_STORAGE_ENGINE=1 CMake option was ignored but should not have been. If -

DWITH_EXAMPLE_STORAGE_ENGINE=0 is given, the EXAMPLE storage engine is built as a plugin. (Bug

#70859, Bug #17772560, Bug #30133062)

References: See also: Bug #18324650.

Changes in MySQL 5.6.45 (2019-07-22, General Availability)

• Functionality Added or Changed

• Bugs Fixed

Functionality Added or Changed

• Microsoft Windows: A new warning message now reminds DBAs that connections made using the

MySQL named pipe on Windows has limited the permissions a connector can request on the named

pipe.

Previously, the named_pipe_full_access_group system variable was set to a value that maps to

the built-in Windows Everyone group (SID S-1-1-0) by default. However, this group is not ideal and

MySQL 5.6 Release Notes

should be replaced with a group that restricts its membership for connectors that are unable to request

fewer permissions on the MySQL named pipe.

The new warning is written to the error log at startup if the string value assigned to

named_pipe_full_access_group is '*everyone*' (or the Windows System Language equivalent)

and named pipes are enabled. In addition, the warning is written to the error log and raised to the client if

the system variable is reset to the Everyone group at runtime. (WL #12670)

Bugs Fixed

• InnoDB: A query that scanned the primary key of a table did not return the expected result. (Bug

#28104394, Bug #91032)

• InnoDB: A full-text cache lock taken when data is synchronized was not released if the full-text cache

size exceeded the full-text cache size limit. (Bug #25289359)

• InnoDB: Client sessions using different auto_increment_increment values while performing

concurrent insert operations could cause a duplicate key error. (Bug #15851528, Bug #67526)

References: Reverted patches: Bug #14049391, Bug #65225.

• Replication: In query log events in the binary log, the thread ID used for the execution of DROP TABLE

and DELETE statements was identified incorrectly or not at all. On a multi-threaded replication slave,

where temporary tables were involved (which require the correct thread ID as they are session specific),

this omission resulted in errors when using mysqlbinlog to replay the binary log for point-in-time

recovery. The thread ID is now set correctly. (Bug #28642318, Bug #92398)

• Installing from RPM packages could result in an error log with incorrect permissions. (Bug #29702462)

• Enabling audit log encryption could cause a server exit. (Bug #29549327)

• MySQL Installer did not install OpenSSL DLL dependencies if the Development component was not

selected. (Bug #29423421, Bug #94168, Bug #30199579, Bug #96573)

• The parser could leak memory for certain multiple-statement queries. (Bug #29419820)

• MySQL does not support OpenSSL session tickets, but did not set the SSL_OP_NO_TICKET flag to

inform OpenSSL of that. The flag is now set. (Bug #27655493)

• UpdateXML() did not always free memory properly in certain cases. (Bug #27312862)

• Empty values in the name column of the mysql.plugin system table caused the server to exit during

startup. (Bug #27302459)

• Some PROXY grants were not replicated to slaves, causing incorrect replication. (Bug #23289541, Bug

#81424, Bug #23623115)

• If an INSTALL PLUGIN statement contained invalid UTF-8 characters in the shared library name, it

caused the server to hang (or to raise an assertion in debug builds). (Bug #14653594, Bug #23080148,

Bug #27167197)

Changes in MySQL 5.6.44 (2019-04-25, General Availability)

Beginning with MySQL 5.6.44, Oracle no longer provides binaries for SUSE 11.

• Packaging Notes

• Security Notes

MySQL 5.6 Release Notes

• Bugs Fixed

Packaging Notes

• The libevent library bundled with MySQL was upgraded to version 2.1.8. (Bug #28207237, Bug

#29041505, Bug #29055011)

Security Notes

• The linked OpenSSL library for the MySQL Commercial Server has been updated to version

1.0.2r. Issues fixed in the new OpenSSL version are described at http://www.openssl.org/news/

vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #28988091)

Bugs Fixed

• InnoDB: The INDEX_LENGTH value in INFORMATION_SCHEMA.TABLES was not updated when adding

an index. (Bug #19811005)

• Partitioning: An AUTO_INCREMENT key added to a partitioned table by an ALTER TABLE statement

using ALGORITHM=INPLACE restarted on each partition. (Bug #92241, Bug #28573894)

• Replication: If an applier thread was stopped while it was in the process of opening a table, no error

was set, which could result in a segmentation fault or assertion depending on the build type. Error

handling is now correctly activated in this situation. (Bug #28864557)

• Replication: If a storage engine has the capability to log in STATEMENT format but not in ROW format,

when binlog_format is set to STATEMENT, an unsafe SQL statement should be logged and a warning

message should be written to the error log. However, such statements were instead not executed and an

error message was written to the error log, which is the correct behavior when binlog_format is set to

MIXED or ROW. The issue has now been corrected so that unsafe statements are logged with a warning

as expected when binlog_format is set to STATEMENT. (Bug #28429993, Bug #73936)

• Microsoft Windows: Validity testing for the named_pipe_full_access_group system variable did

not account for NULL values. (Bug #29256690)

• MySQL 5.6 did not build with maintainer mode enabled with GCC 7. (Bug #29048768)

• A damaged mysql.user table could cause a server exit. (Bug #28986737)

• mysqladmin shutdown did not wait for mysqld to shut down. (Bug #28466137, Bug #91803)

References: This issue is a regression of: Bug #25364806.

• Some status variable values could temporarily increase before returning to their original value. (Bug

#27839644, Bug #90351)

• The binary file for the udf_example loadable function was omitted from binary distributions. (Bug

#26115002, Bug #29178542)

• Compiling the InnoDB memcached plugin did not work on some platforms where MySQL was

configured using -DWITH_LIBEVENT=system, for libevent version 2.0 or higher. (Bug #80073, Bug

#22573379, Bug #23567441)

• Ubuntu 14.04 and SLES 11 are EOL, and no longer supported.

MySQL 5.6 Release Notes

Changes in MySQL 5.6.43 (2019-01-21, General Availability)

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

Security Notes

• The linked OpenSSL library for the MySQL Commercial Server has been updated to version

1.0.2q. Issues fixed in the new OpenSSL version are described at http://www.openssl.org/news/

vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #28988091)

Functionality Added or Changed

• Microsoft Windows: The access control granted to clients on the named pipe created by the MySQL

server now is set to the minimum necessary for successful communication on Windows. Newer MySQL

client software can open named pipe connections without any additional configuration. If older client

software cannot be upgraded immediately, the new named_pipe_full_access_group server

system variable can be used to give a Windows group the necessary permissions to open a named pipe

connection. Membership in the full-access group should be restricted and temporary. (WL #12445)

Bugs Fixed

• Replication: A patch to correct the handling of quotes for identifiers in ROLLBACK TO SAVEPOINT

statements in the binary log was not correctly applied to subsequent MySQL versions. (Bug #28569645)

• Replication: In some circumstances, the CHANGE MASTER TO statement could not

be used on a replication slave if the master info log had been changed from a table

(master_info_repository=TABLE) into a file (master_info_repository=FILE). (Bug

#28529558)

• Replication: The value returned by a SHOW SLAVE STATUS statement for the total combined size of

all existing relay log files (Relay_Log_Space) could become much larger than the actual disk space

used by the relay log files. The I/O thread did not lock the variable while it updated the value, so the SQL

thread could automatically delete a relay log file and write a reduced value before the I/O thread finished

updating the value. The I/O thread then wrote its original size calculation, ignoring the SQL thread's

update and so adding back the space for the deleted file. The Relay_Log_Space value is now locked

during updates to prevent concurrent updates and ensure an accurate calculation. (Bug #26997096, Bug

#87832)

• Replication: If the relay log index file was temporarily locked for viewing by a backup process for a

replication slave, and MySQL Server also attempted to access the file at that time for rename or delete

operations, the backup completed with warnings, but MySQL Server experienced an unexpected halt.

MySQL Server now retries the file access operation a number of times in case this or a similar scenario

is the explanation and the file becomes available again before long. (Bug #25839610)

• The server permitted creation of databases with the same name as redo log files, which could result in

unexpected server behavior. Such names are no longer permitted as database names. (Bug #28867993)

• When a subquery contained a UNION, the count of the number of subquery columns was calculated

incorrectly. (Bug #28499924)

MySQL 5.6 Release Notes

• Comparing log file names as strings using the memcmp() function resulted in uninitialized memory

read errors. The comparison now uses the strncmp() function. Thanks to Zsolt Parragi and Laurynas

Biveinis for their contributions. (Bug #28178776, Bug #90238)

• The transformation of IN subquery predicates into semijoins was not handled correctly for a very large

number of tables. (Bug #28004674)

• Executing a prepared statement to do a multiple-row insert with large number of placeholders consumed

excessive memory and could execute slowly. (Bug #27703912)

• The parser accepted invalid SET statement syntax in trigger definitions that could result in a server exit.

(Bug #27595603)

• MyISAM index corruption could occur for bulk-insert and table-repair operations that involve the repair-

by-sorting algorithm and many (more than 450 million) rows. (Bug #26929724, Bug #88003, Bug

#28483283)

• A query employing a dynamic range and an index merge could use more memory than expected. (Bug

#89953, Bug #27659490)

Changes in MySQL 5.6.42 (2018-10-22, General Availability)

• Packaging Notes

• Functionality Added or Changed

• Bugs Fixed

Packaging Notes

• Binary packages that include curl rather than linking to the system curl library now use curl 7.60.0

rather than 7.45.0. (Bug #28043702)

• The zlib library bundled with MySQL has been upgraded from version 1.2.3 to version 1.2.11. MySQL

implements compression with the help of the zlib library.

The zlib compressBound() function in zlib 1.2.11 returns a slightly higher estimate of the buffer size

required to compress a given length of bytes than it did in zlib version 1.2.3. The compressBound()

function is called by InnoDB functions that determine the maximum row size permitted when creating

compressed InnoDB tables or inserting rows into compressed InnoDB tables. As a result, CREATE

TABLE ... ROW_FORMAT=COMPRESSED or INSERT and UPDATE operations with row sizes very

close to the maximum row size that were successful in earlier releases could now fail. For additional

information, see Changes in MySQL 5.6. (WL #10551)

Functionality Added or Changed

• Previously, file I/O performed in the I/O cache in the mysys library was not instrumented, affecting in

particular file I/O statistics reported by the Performance Schema about the binary log index file. Now,

this I/O is instrumented and Performance Schema statistics are accurate. Thanks to Yura Sorokin for the

contribution. (Bug #27788907, Bug #90264)

Bugs Fixed

• InnoDB: An ALTER TABLE operation that added a primary key produced a segmentation fault. (Bug

#28395278)

References: This issue is a regression of: Bug #27753193.

MySQL 5.6 Release Notes

• InnoDB: An assertion was raised during an OPTIMIZE TABLE operation. (Bug #27753193)

• InnoDB: A foreign key constraint name was duplicated during a rename table operation, causing a

failure during later query execution. (Bug #27545888)

• InnoDB: The location of the Innodb Merge Temp File that reported by the wait/io/file/innodb/

innodb_temp_file Performance Schema instrument was incorrect. (Bug #21339079, Bug #77519)

• Replication: When FLUSH statements for specific log types (such as FLUSH SLOW LOGS) resulted in

an error, the statements were still written to the binary log. This stopped replication because the error

had occurred on the master, but did not occur on the slave. MySQL Server now checks on the outcome

of these FLUSH statements, and if an error occurred, the statement is not written to the binary log. (Bug

#24786290, Bug #83232)

• Microsoft Windows: On Windows, uninstallation of the MySQL Server MSI package through MySQL

Installer produced a spurious popup window. (Bug #27463864)

• Concurrent INSERT and SELECT statements on a MERGE table could result in a server exit. (Bug

#28379285)

• MySQL Server and test RPM packages were missing perl-Data-Dumper as a dependency. (Bug

#28144933, Bug #72926)

• For the mysql client, the -b short option was associated with two long options, --no-beep and --

binary-as-hex. The -b option now is associated only with --no-beep. (Bug #28093271)

• Very long table keys were handled incorrectly on replication slaves. (Bug #27930505)

• During server startup/shutdown, PID files could be mishandled. (Bug #27919254)

• For MEMORY tables, memory overflow errors could occur. (Bug #27799513)

• When converting from a BLOB (or TEXT) type to a smaller BLOB (or TEXT) type, no warning or error was

reported informing about the truncation or data loss. Now an appropriate error is issued in strict SQL

mode and a warning in nonstrict SQL mode. (Bug #27788685, Bug #90266)

• Failure to create a temporary table during a MyISAM query could cause a server exit. Thanks to

Facebook for the patch. (Bug #27724519, Bug #90145)

• An attempted read of an uncommitted transaction raised an assertion. (Bug #26876608)

• ALTER TABLE ... REORGANIZE PARTITION ... could result in incorrect behavior if any partition

other than the last was missing the VALUES LESS THAN part of the syntax. (Bug #26791931)

• yum update did not properly update from RHEL5 RPM packages to current packages. (Bug

#20560761)

• It was possible for a subquery that used a unique key on a column allowing NULL to return multiple

rows. (Bug #88670, Bug #27182010)

Changes in MySQL 5.6.41 (2018-07-27, General Availability)

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

MySQL 5.6 Release Notes

Security Notes

• The linked OpenSSL library for the MySQL Commercial Server has been updated to version

1.0.2o. Issues fixed in the new OpenSSL version are described at http://www.openssl.org/news/

vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #28025379)

Functionality Added or Changed

• Previously, for the --ssl-verify-server-cert option, the client checked whether the host name

that it used for connecting matched the Common Name value in the certificate but not the Subject

Alternative Name value. Now, if MySQL was built using OpenSSL 1.0.2 or higher, the client checks

whether the host name matches either the Subject Alternative Name value or the Common Name value

in the server certificate. Host name identity verification also works with certificates that specify the

Common Name using wildcards. Thanks to Daniël van Eeden for a patch on which this change was

based. (Bug #16211011, Bug #68052, Bug #27511233, Bug #89578)

Bugs Fixed

• InnoDB: A schema mismatch error reported during an import tablespace operation failed to print

mismatched table flags in a readable format. (Bug #27542720)

• InnoDB: A DDL operation failed to wait for a FULLTEXT index optimization operation to finish. (Bug

#27326796)

References: This issue is a regression of: Bug #24938374.

• InnoDB: A failing assertion occurred after initiating a memcached get operation. (Bug #26876594)

• InnoDB: A corrupt index ID encountered during a foreign key check raised an assertion. (Bug

#26654685)

• Replication: When a transaction larger than the binary log transaction cache size

(binlog_cache_size) was flushed to a temporary file during processing, and the flush failed due to

a lack of space in the temporary directory, the flush error was not handled correctly. No message was

written to the error log, and the binary log cache was not cleared after the transaction was rolled back.

Now, in this situation, the server takes an appropriate action based on the binlog_error_action

setting (shut down the server or halt logging), and writes a message to the error log. When the

transaction is rolled back, the server checks for flush errors and clears the binary log cache if any

occurred. (Bug #27399620, Bug #89272)

• Replication: When GTIDs are in use for replication, replicated transactions that are filtered out on the

slave are persisted. If binary logging is enabled on the slave, the filtered-out transaction is written to

the binary log as a Gtid_log_event followed by an empty transaction containing only BEGIN and

COMMIT statements. If binary logging is disabled, the GTID of the filtered-out transaction is written

to the mysql.gtid_executed table. This process ensures that there are no gaps in the set of

executed GTIDs, and that the filtered-out transactions are not retrieved again if the slave reconnects

to the master. Previously, this process was not done for CREATE DATABASE, ALTER DATABASE, and

DROP DATABASE statements, but it is now carried out for those statements as well as for others. (Bug

#27308751, Bug #88891)

• Replication: On a multithreaded slave, when a STOP SLAVE statement is executed on the slave,

followed by a START SLAVE statement, the error log can report a different position in the binary log for

MySQL 5.6 Release Notes

the slave SQL thread when exiting, compared to the position reported for the slave SQL thread at the

subsequent initialization.

For a multithreaded slave, the position reported for the SQL thread on exit is a low water mark, up to

which the replication stream is consistent and has no gaps. Transactions appearing before the position

are guaranteed to have committed, but transactions after the position may have committed or not.

However, this low water mark was being reported before the process to stop the worker threads was

actually carried out, and the low water mark was subsequently updated by a checkpoint routine during

that process. The timing of the log message has now been changed so that the final low water mark is

reported as the position for the SQL thread on exit. (Bug #27300658)

• A heap overflow vulnerability in the MySQL client library was fixed. (Bug #27980823)

• An unencrypted connection could result from a client connection attempt specifying that an encrypted

connection was required, if the server was not configured to support SSL. (Bug #27759871)

• On Windows, if the Visual C++ Redistributable for Visual Studio had been removed, MySQL

uninstallation using the MSI installer failed. (Bug #27621546)

• A memory leak in the pfs-t unit test was fixed. Thanks to Yura Sorokin for the patch. (Bug #27440735,

Bug #89384)

• With automatic_sp_privileges enabled, the EXECUTE and ALTER ROUTINE privileges were not

correctly granted to routine creators. (Bug #27407480)

• Mishandling of internal privilege structures could cause a server exit. (Bug #27230925)

• The UNION of a user-defined variable and a DECIMAL column produced an incorrect result when using a

UTF8 character set. (Bug #27197235)

• mysqldump exited abnormally for large --where option values. (Bug #26171967, Bug #86496, Bug

#27510150)

• For MyISAM tables, particular sequences of INSERT and DELETE statements could cause table

corruption. (Bug #25541037)

• FORCE INDEX had no effect on a query that used GROUP BY, ORDER BY, and LIMIT together. (Bug

#90817, Bug #27998526)

Changes in MySQL 5.6.40 (2018-04-19, General Availability)

• Functionality Added or Changed

• Bugs Fixed

Functionality Added or Changed

• If the server PID file is configured to be created in a world-writable location, the server now issues a

warning suggesting use of a more secure location. (Bug #26585560)

Bugs Fixed

• NDB Cluster: MySQL NDB Cluster encountered race conditions compiling lex_hash.h. (Bug

#24931655, Bug #83477, Bug #27470071, Bug #89482)

• InnoDB: A REPLACE operation on a temporary table raised an assertion. (Bug #27225649, Bug

#27229072)

MySQL 5.6 Release Notes

• InnoDB: A tablespace import operation on a server with a default row format of REDUNDANT raised an

assertion failure. (Bug #26960215)

• InnoDB: Evaluation of a subquery in a resolving function raised an assertion. (Bug #26909960)

• InnoDB: An online DDL operation that rebuilds the table raised an assertion when the last insert log

record to be applied was split across two pages. (Bug #26696448, Bug #87532)

• InnoDB: A RENAME TABLE operation that renamed the schema failed to rename full-text search

common auxiliary tables that were left behind when the full-text search index was removed previously,

resulting in a assertion failure when attempting to drop the old schema. (Bug #26334149)

• Replication: A number of changes were made to the binary log decoding procedure to improve handling

of invalid or corrupted binary log entries. (Bug #24365972)

• An invalid input polygon for spatial functions could lead to undefined server behavior. Now the server

returns NULL. (Bug #27230859, Bug #88801)

• Adding a unique index to an InnoDB table on which multiple locks were held could raise an assertion.

(Bug #27216817)

• For some statements, the FILE privilege was not properly checked. (Bug #27160888)

• ST_Touches() could fail due to a missing null pointer check. (Bug #27081349)

• A multiple-insert statement on a table containing a FULLTEXT key and a FTS_DOC_ID column caused a

server error. (Bug #27041445, Bug #88267)

References: This issue is a regression of: Bug #22679185.

• An ALTER TABLE operation attempted to set the AUTO_INCREMENT value for table in a discarded

tablespace. (Bug #26935001)

• Dropping an index from a system table could cause a server exit. (Bug #26881798)

• A server exit could result from simultaneous attempts by multiple threads to register and deregister

metadata Performance Schema objects. (Bug #26502135)

• The thread pool plugin logged too much information for failed connections. (Bug #26368725, Bug

#86863)

• For debug builds, using KILL to terminate a stored routine could raise an assertion. Thanks to Laurynas

Biveinis for the patch. (Bug #26040870, Bug #86260)

• MySQL client programs could exit unexpectedly if malformed client/server protocol packets were

received. (Bug #25471090)

• Incorrect handling by the CONNECTION_CONTROL plugin of an internal hash led to spurious messages in

the error log and eventual server exit. (Bug #25052009)

• Building MySQL using parallel compilation sometimes failed with an attempt to compile sql_yacc.yy

before lex_token.h had been created. (Bug #21680733, Bug #27470071, Bug #89482)

• On Windows, sql_yacc.cc and sql_yacc.h were generated twice during the build process. This can

lead to compilation failure if parallel processes are permitted. (Bug #19060850, Bug #27470071, Bug

#89482)

• The audit_log plugin did not log placeholder values for prepared statements. (Bug #16617026)

• NULLIF() with a TIMESTAMP argument could produce truncated output. (Bug #12616286, Bug #61378)

MySQL 5.6 Release Notes

• MAX() for DATE values smaller than year 100 produced incorrect results. (Bug #12546797, Bug #61100)

• Compilation could fail due to a missing dependency on lex_token.h for sql_yacc.cc.o. (Bug

#76235, Bug #20678411, Bug #27470071, Bug #89482)

• A WHERE condition of the form column_value < ALL (select_expression) did not always

evaluate as TRUE when the select_expression did not return any rows. (Bug #61799, Bug

#12762381)

• The optimizer incorrectly optimized away a subquery selecting a MIN() or MAX() expression even when

the subquery was correlated with or depended on an outer reference. An example of such a query is

shown here:

SELECT (

SELECT MIN(42) FROM t2 WHERE t2.pk = t1.pk

) AS scalar_subqry

FROM t1;

In this case, the optimizer reduced SELECT MIN(42) FROM T2 to a constant value (42), and the

correlation predicate WHERE T2.pk = T1.pk was never checked during query execution. (If the

predicate were executed, it would not have qualifed any rows from the subquery, and would have

evaluated as NULL.) (Bug #53485, Bug #11761032)

Changes in MySQL 5.6.39 (2018-01-15, General Availability)

• Configuration Notes

• Security Notes

• Test Suite Notes

• Bugs Fixed

Configuration Notes

• For RHEL, SLES, and Fedora RPMs, the default plugin directory for debug builds has been changed

from /usr/lib64/mysql/plugin to /usr/lib64/mysql/plugin/debug. (Bug #27072155, Bug

#88363)

Security Notes

• Incompatible Change: Passwords are now restricted to a maximum of 256 characters for the

sha256_password authentication plugin, and for the PASSWORD() function when old_passwords=2.

Also, the number of password hashing rounds is capped to limit CPU time used. (Bug #27099029, Bug

#27194270)

• The linked OpenSSL library for the MySQL Commercial Server has been updated to version

1.0.2n. Issues fixed in the new OpenSSL version are described at http://www.openssl.org/news/

vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #27212666, Bug #27236394)

Test Suite Notes

• Documentation for the MySQL Test Suite is now maintained in the MySQL source tree using Doxygen

(see the MySQL Server Doxygen documentation, available at https://dev.mysql.com/doc/index-

other.html.) The related Unix man pages that previously were produced from the old test suite manual

MySQL 5.6 Release Notes

are no longer updated and have gone out of date. Consequently, they are no longer included in MySQL

distributions. (Bug #27021754)

Bugs Fixed

• InnoDB: An ALTER TABLE operation caused the server to halt. (Bug #26492721)

• InnoDB: A FLUSH TABLES operation failed to drop an aborted index. While removing the table from the

cache, the clustered index was dropped prior to checking for the aborted index. (Bug #26256456, Bug

#86607)

• InnoDB: Warnings that should only appear in debug builds of MySQL were printed to the error log when

the length of the history list exceeded 2000000. (Bug #24296076, Bug #82213)

• InnoDB: Full-text search on indexed columns that use a binary collation did not return case-sensitive

matches. (Bug #21625016, Bug #78048)

• Partitioning: In certain cases when fetching heap records a partition ID could be set to zero. (Bug

#86255, Bug #26034430)

• Replication: With semisynchronous replication in use, if RESET MASTER was issued while an active

transaction was waiting for an acknowledgement from the slave, the count of waiting sessions in the

Rpl_semi_sync_master_wait_sessions server status variable was incorrect after the wait was

completed. (Bug #26748533)

• Microsoft Windows: On Windows, with the myisam_use_mmap and flush system variables enabled,

MyISAM did not always flush table files properly. (Bug #26880757)

• Microsoft Windows: On Windows, resolution was improved of a timer used for query performance

assessment. (Bug #22305994, Bug #26734457)

• VALUES() was not handled correctly in some cases. (Bug #26881946)

References: See also: Bug #19601973, Bug #17458914.

• The Performance Schema now stores rewritten rather than raw SQL statement text when available. (Bug

#26732229)

• Incorrect results or a server exit could result when SHA2() was passed a user-defined variable in some

character sets. (Bug #26704451)

• Creating a table with excessive index information could cause a server exit. (Bug #26529369)

• REFERENCES privilege checking could use the incorrect database in some cases. (Bug #26106655)

• Some statements could cause a buffer overflow in the digest code. Thanks to Laurynas Biveinis and

Roel van de Paar for the patch. (Bug #26021187)

• Incorrect results could occur on a table with a unique index when the optimizer chose a Loose Index

Scan even though the unique index had no index extensions. (Bug #25989915, Bug #86165, Bug

#26532061, Bug #87207)

References: This issue is a regression of: Bug #21749123, Bug #78244.

• Executing a stored procedure containing a statement that created a table from the contents of certain

SELECT statements could result in a memory leak. (Bug #25586773)

• For geometry calculations, invalid input parameters could lead to an incorrect result buffer and cause an

assertion to be raised or a server exit. (Bug #25062396)

MySQL 5.6 Release Notes

• Setting the MYSQL_GROUP_SUFFIX environment variable had no effect. (Bug #23072792)

• A circular dependency problem involving sql/sql_builtin.cc was resolved. (Bug #16877045)

• A prepared statement containing an ORDER BY list that referred to a parameter was not always handled

correctly. (Bug #87863, Bug #26867652)

Changes in MySQL 5.6.38 (2017-10-16, General Availability)

• Packaging Notes

• Bugs Fixed

Packaging Notes

• mysqlcheck was missing in the MySQL Server Docker image, which prevented mysql_upgrade from

running. (Bug #26400146, Bug #86968)

Bugs Fixed

• InnoDB: Replication lag occurred on slave instances during large update operations on tables with many

partitions. (Bug #25687813, Bug #85352)

• InnoDB: A failure occurred during an end range comparison. (Bug #25669686)

• InnoDB: Enabling the innodb_buffer_pool_load_now setting failed in read-only mode. The event

that signals the buffer pool load thread was not initialized. (Bug #25586766)

• InnoDB: A long wait for a dictionary operation lock held by a full-text search synchronization operation

caused a server exit. (Bug #24938374, Bug #26376681, Bug #26376239)

• Partitioning: Queries involving NULL were not always handled correctly on tables that were partitioned

by LIST. (Bug #76418, Bug #20748521)

References: See also: Bug #86255, Bug #26034430.

• Replication: When replicating a partitioned table with an index, on a replication slave where

HASH_SCAN was specified as part of the slave_rows_search_algorithms setting, the slave I/O

thread sometimes stopped with an error HA_ERR_KEY_NOT_FOUND. (Bug #26137159)

• Replication: Replication clients no longer enable LOCAL capability for LOAD DATA statements, because

they do not use LOAD DATA LOCAL statements. (Bug #24763131)

• Replication: In case of a failure while creating multiple slave applier worker threads, some threads

would be left orphaned and their resources would not be collected. Thanks to Laurynas Biveinis for his

contribution to fixing this bug. (Bug #24679056, Bug #82980)

• MSI packages for Windows failed to detect when Microsoft Visual C++ 2010 Redistributable Package

was installed. (Bug #26501092, Bug #87139)

• yaSSL could incorrectly perform TLS cipher negotiation. (Bug #26482173)

• The server failed to check the maximum path length for partition names. (Bug #26390632)

• Identifiers containing a mixt of backslashes and backticks could be parsed incorrectly. (Bug #26372491)

• Source packages for Debian platforms contained prebuilt debug binaries, causing build failures on any

architectures other than the one on which those binaries were built. (Bug #26186911)

• The test database was missing from MSI packages. (Bug #26168832)

MySQL 5.6 Release Notes

• Uninstalling the daemon_memcached plugin caused a serious error. (Bug #25909540)

• Selecting from a view could yield different results with materialization enabled versus materialization

disabled. (Bug #25782811, Bug #85622)

• The Performance Schema failed to check the maximum host length for client connections. (Bug

#25510805)

• A server error occurred when a full text search result exceeded the

innodb_ft_result_cache_limit setting. The patch for this bug also backports a related patch (Bug

#21140111). (Bug #25033538)

• If a stored function was considered a constant by the optimizer, calling it from a subquery in a NOT IN

condition in the WHERE clause could cause a server exit. (Bug #23577867)

• A mysqldump memory leak was fixed. Thanks to Yura Sorokin for the patch. (Bug #23531150, Bug

#81714)

• If a session rolled back to a savepoint and then was killed, the statements up to the point of the

savepoint could be committed. (Bug #22350047, Bug #79596)

• For clients that used Connector/Python and authenticated using the sha256_password plugin, the

server could handle connections incorrectly. (Bug #21421642)

• NAME_CONST() can return null if incorrect arguments are given. In some cases, this was not handled

and could cause a server exit. (Bug #19143243, Bug #26361149)

Changes in MySQL 5.6.37 (2017-07-17, General Availability)

• Packaging Notes

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

Packaging Notes

• mysqladmin was added to Docker/Minimal packages because it is needed by InnoDB Cluster. (Bug

#25998285)

• For Windows, MSI installer packages now include a check for the required Visual Studio redistributable

package, and produce a message asking the user to install it if it is missing. (Bug #25658832)

Security Notes

• The linked OpenSSL library for the MySQL Commercial Server has been updated to version

1.0.2l. Issues fixed in the new OpenSSL version are described at http://www.openssl.org/news/

vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #26160962)

Functionality Added or Changed

• The mysql client now supports a --binary-as-hex option that causes display of binary data using

hexadecimal notation (0xvalue). Thanks to Daniël van Eeden for the patch. (Bug #25340722, Bug

#84391)

MySQL 5.6 Release Notes

• mysqlaccess now looks for its configuration file only in the SYSCONFDIR directory and /etc. (Bug

#25043674)

Bugs Fixed

• InnoDB: The server allocated memory unnecessarily for an operation that rebuilt the table. (Bug

#25573565, Bug #85043)

• InnoDB: When using an index merge optimizer switch, a SELECT COUNT(*) operation sometimes

returned 0. Partitioning code incorrectly performed a memcpy instead of a column copy of columns read

by the index, causing the wrong records to be copied. (Bug #25332330, Bug #81031)

• Replication: A USE statement that followed a SET GTID_NEXT statement sometimes had no effect.

(Bug #26128931)

• Replication: If the binary log on a master server was rotated and a full disk condition occurred on the

partition where the binary log file was being stored, the server could stop unexpectedly. The fix adds

a check for the existence of the binary log when the dump thread switches to next binary log file. If the

binary log is disabled, all binary logs up to the current active log are transmitted to slave and an error is

returned to the receiver thread. (Bug #25076007)

• Replication: If a relay log index file named relay log files that did not exist, RESET SLAVE ALL

sometimes did not fully clean up properly. (Bug #24901077)

• Replication: mysqlbinlog, if invoked with the --raw option, does not flush the output file until

the process terminates. But if also invoked with the --stop-never option, the process never

terminates, thus nothing is ever written to the output file. Now the output is flushed after each event.

(Bug #24609402)

• Replication: A memory leak in mysqlbinlog was fixed. The leak happened when processing fake

rotate events, or when using --raw and the destination log file could not be created. The leak only

occurred when processing events from a remote server. Thanks to Laurynas Biveinis for his contribution

to fixing this bug. (Bug #24323288, Bug #82283)

• Replication: Multithreaded slaves could not be configured with small queue sizes using

slave_pending_jobs_size_max if they ever needed to process transactions larger than that

size. Any packet larger than slave_pending_jobs_size_max was rejected with the error

ER_MTS_EVENT_BIGGER_PENDING_JOBS_SIZE_MAX, even if the packet was smaller than the limit

set by slave_max_allowed_packet.

With this fix, slave_pending_jobs_size_max becomes a soft limit rather than a hard

limit. If the size of a packet exceeds slave_pending_jobs_size_max but is less than

slave_max_allowed_packet, the transaction is held until all the slave workers have empty

queues, and then processed. All subsequent transactions are held until the large transaction has been

completed. The queue size for slave workers can therefore be limited while still allowing occasional

larger transactions. (Bug #21280753, Bug #77406)

• Linux: The generic Linux build for MySQL 8.0 is now built on Oracle Linux 6 using glibc 2.12. Systems

that use the build need to have glibc 2.12 or later installed on them. (Bug #26005558)

• mysqldump could write database names in USE statements incorrectly. (Bug #25998635)

• If the mysql_stmt_close() C API function was called, it freed memory that later could be accessed if

mysql_stmt_error(), mysql_stmt_errno(), or mysql_stmt_sqlstate() was called. To obtain

error information after a call to mysql_stmt_close(), call mysql_error(), mysql_errno(), or

mysql_sqlstate() instead. (Bug #25988681)

MySQL 5.6 Release Notes

• Queries could be cached incorrectly, leading to incorrect query results, under these circumstances:

InnoDB table; rows are being inserted but have not yet been committed; a query uses the table as a

base table in a derived table; the optimizer chooses to materialize the derived table. (Bug #25943038,

Bug #86047)

• Man pages for a few utilities were missing from Debian/Ubuntu packages. (Bug #25811814)

• The field-t unit test failed to run with AddressSanitizer enabled. Thanks to Laurynas Biveinis for the

patch. (Bug #25803823, Bug #85678)

• Debian client packages were missing information about conflicts with native packages. (Bug #25799475)

• The Perl path in #! lines at the beginning of Perl scripts has been adjusted to /usr/local/bin/perl

for FreeBSD 11. (Bug #25719975)

• The server exited abnormally attempting to access invalid memory. (Bug #25501659)

• A race condition could occur for CREATE TABLE statements with DATA DIRECTORY or INDEX

DIRECTORY clauses. (Bug #25451091)

• MySQL compilation in different directories produced different builds to leakage of absolute paths into

debug information and __FILE__. (Bug #25436469, Bug #84608, Bug #25859274, Bug #85855)

• mysqld_failed to start the server if the --datadir option was specified with a relative path name.

(Bug #25364806)

• With read_only enabled, creation of non-TEMPORARY tables by non-SUPER users was permitted under

certain conditions. (Bug #25250768)

• Certain stored functions, if used in a query WHERE clause, could be handled using Index Condition

Pushdown (which should not happen), resulting in a server exit. (Bug #25196653, Bug #25174454)

• On x86 machines, the uint3korr() macro read 4 bytes of data instead of the intended 3 bytes. (Bug

#24807826, Bug #83264)

• An assertion was raised during a fetch operation by the memcached plugin. (Bug #24605783)

• Queries that contained UNION in a subquery and GROUP BY could return incorrect results. (Bug

#24595639)

• LOAD XML performance became noticeably slower when the XML file being read contained a great

many spaces, such as those introduced by indenting or pretty-printing. Now all leading whitespace is

trimmed from each such value before reading it into memory. (Bug #16212207)

Changes in MySQL 5.6.36 (2017-04-10, General Availability)

• Compilation Notes

• Configuration Notes

• Packaging Notes

• Security Notes

• Thread Pool Notes

• Functionality Added or Changed

• Bugs Fixed

MySQL 5.6 Release Notes

Compilation Notes

• Windows builds now use the default runtime libraries (builds use the /MD flag). (Bug #25611609)

• CMake support was added for compiling with Developer Studio 12.6. (Bug #25384295)

Configuration Notes

• MySQL failed to compile if -DENABLE_DEBUG_SYNC=OFF AND -DWITH_DEBUG=ON were both given.

The ENABLE_DEBUG_SYNC option has been removed and enabling WITH_DEBUG enables Debug Sync.

(Bug #18374703)

Packaging Notes

• Microsoft Windows: Reminder: MySQL 5.6 requires the Microsoft Visual C++ 2010 Redistributable

Package to run on Windows platforms. Users should make sure the package has been installed on the

system before starting the server. The package is available at the Microsoft Download Center.

• Changes in RPM package structure require a larger set of packages to be removed to install MySQL

Server cleanly. (Bug #25603087)

• To avoid potential race conditions, Debian packages now use the GNU install utility rather than a

combination of mkdir, touch, and chown. (Bug #25258829)

• CMake-generated packaging for Debian/Ubuntu packages was refactored for improved maintainability.

The change includes updated logic for correctly replacing native distribution packaging in Debian and

Ubuntu. (Bug #25126961, Bug #25251872, Bug #84198)

Security Notes

• The linked OpenSSL library for the MySQL Commercial Server has been updated to version

1.0.2k. Issues fixed in the new OpenSSL version are described at http://www.openssl.org/news/

vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #25768671, Bug #25615451)

• The mysql_options() C API function now supports a MYSQL_OPT_SSL_MODE option. The only

permitted option value is SSL_MODE_REQUIRED, to require an encrypted connection to the server. It

causes mysql_real_connect() to fail if an encrypted connection cannot be obtained, without falling

back to an unencrypted connection. Thus, mysql_real_connect() returns an error if the server

does not support SSL or the client is not configured to use SSL. The client/server exchange terminates

immediately after the initial server packet has been received if the server indicates that it does not

support SSL.

To require an encrypted connection in MySQL 8.0, the standard MySQL client programs call

mysql_options() to set MYSQL_OPT_SSL_MODE if the --ssl-mode=REQUIRED command-line

option was specified. Third-party applications that must be able to require encrypted connections can

use the same technique. For details, see mysql_ssl_set().

The minor C API version number was not incremented for this change. Application programs compiled

for MySQL 8.0 that require MYSQL_OPT_SSL_MODE may fail to operate properly if the dynamic loader

provides an older client library without MYSQL_OPT_SSL_MODE. Such applications must be written

to handle this possibility by checking whether the mysql_options() call succeeds or fails. (Bug

#25575605)

MySQL 5.6 Release Notes

Thread Pool Notes

• To improve thread_pool plugin performance, connection authentication and initialization have been

moved from the acceptor thread to the thread pool worker threads that handle client connections. This

enables the acceptor thread to handle new connections at a higher rate with reduced latency. The

INFORMATION_SCHEMA TP_THREAD_GROUP_STATE table now contains a CONNECT_THREAD_COUNT

column that indicates the number of threads that are processing or waiting to process connection

initialization and authentication. There can be a maximum of four connection threads per thread group;

these threads expire after a period of inactivity. (Bug #17159742, WL #7195, WL #10287)

Functionality Added or Changed

• Replication: When a negative or fractional timeout parameter was supplied to

WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS(), the server behaved in unexpected ways. With this fix:

• A fractional timeout value is read as-is, with no round-off.

• A negative timeout value is rejected with an error if the server is on a strict SQL mode; if the server is

not on a strict SQL mode, the value makes the function return NULL immediately without any waiting

and then issue a warning.

(Bug #24976304, Bug #83537)

• The performance of UTF-8 binary collations was improved. (Bug #24788778, Bug #83247, Bug

#25076862)

• Consistency and maintainability of Debian/Ubuntu packaging maintainer scripts was improved. (Bug

#23588977)

• mysql_secure_installation is more strict about what it considers valid yes and no responses.

(Bug #13344753, Bug #62925)

Bugs Fixed

• InnoDB: The restriction that required the first undo tablespace to use space ID 1 was removed. The first

undo tablespace may now be assigned a space ID other than 1. Space ID values for undo tablespaces

are still assigned in a consecutive sequence. (Bug #25551311)

• InnoDB: Compiling the server without the Performance Schema caused a build failure. (Bug

#25348787)

• InnoDB: The file handle type name for InnoDB file I/O Performance Schema instrumentation was

changed from os_pfs_file_t to pfs_os_file_t. (Bug #25220118)

• InnoDB: A server exit on restart was caused by missing my_thread_init() and

my_thread_exit() functions for background threads that initialize the st_my_thread_var structure.

(Bug #25167032)

• InnoDB: A memcached read operation with a non-default read batch size configuration resulted in a

server exit. (Bug #25147515)

• InnoDB: An error in code related to table statistics raised an assertion in the dict0stats.cc source

file. (Bug #24585978)

• InnoDB: Performance Schema instrumentation for InnoDB file I/O was disabled on Windows. (Bug

#14025581)

MySQL 5.6 Release Notes

• InnoDB: The row_search_mvcc() function unnecessarily traversed the entire table for a range query,

which occurred when the record was not in the transaction read view. (Bug #84202, Bug #23481444,

Bug #25251375)

• Replication: When using a multithreaded slave (slave_parallel_workers greater than 0) the value

of Seconds_Behind_Master was incorrect when rotating a relay log. (Bug #23532304)

• Ubuntu 12.04 LTS: This is the last release in the MySQL 8.0 series to support Ubuntu 12.04 LTS. As per

the MySQL Support Lifecycle policy regarding ending support for OS versions that are obsolete or have

reached end of life, we plan to discontinue building binaries for the Linux distribution in future releases.

(Bug #25828475)

• Oracle Linux 5, Red Hat Enterprise Linux 5, and CentOS 5: This is the last release in the MySQL 8.0

series to support Oracle Linux 5, Red Hat Enterprise Linux 5, and CentOS 5. As per the MySQL Support

Lifecycle policy regarding ending support for OS versions that are obsolete or have reached end of life,

we plan to discontinue building binaries for those Linux distributions in future releases. Moreover, we

plan to build the generic Linux tarballs for the next release on Oracle Linux 6 using glibc 2.12. (Bug

#25828375)

• mysqldump failed to properly quote certain identifiers in SQL statements written to the dump output.

(Bug #25717383)

• Client preauthorization by the server was missing a length check for a length-encoded string. (Bug

#25714674)

• For Debian/Ubuntu packages, user-defined collation files could be overwritten during MySQL upgrades.

Charset files are now marked as conffiles so that user customizations generate a prompt during

upgrades whether to overwrite them. (Bug #25525628, Bug #84761)

• For CREATE TABLE statements that specified the table name with a database qualifier and included a

DATA DIRECTORY or INDEX DIRECTORY option, an error occurred if there was no default database.

(Bug #25514146, Bug #84861)

• Starting the server with performance_schema_digests_size=1 caused an abnormal exit. (Bug

#25492129, Bug #84786)

• mysqld_safe did not check whether the directory named by the --basedir option existed. (Bug

#25365194)

• mysqld_safe failed if the error log file named by the --log-error option was a FIFO. (Bug

#25356221, Bug #84427)

• mysqld_safe could fail if the --datadir option value ended with a / character. (Bug #25319457)

• A recent change to mysqld_safe caused the mysql.server script to be unable to start it if the base

directory was specified as an absolute path that differed from the compiled-in default absolute path. (Bug

#25319392, Bug #84263)

• The fix for Bug #78777 had different effects depending on whether the Performance Schema is enabled.

(Bug #25309017, Bug #84305)

References: This issue is a regression of: Bug #78777.

• The CONNECTION_CONTROL plugin failed to compile if the Performance Schema was disabled. (Bug

#25308357, Bug #84304)

• For System V init scripts for RPMs, the [mysqld] option-file section was being ignored for some

options, such as pid-file. (Bug #25287707, Bug #84172)

MySQL 5.6 Release Notes

• Init scripts failed to launch mysqld_safe if a non-default base directory was used. (Bug #25261472,

Bug #84219)

• mysqld_safe --no-defaults did not work (inadvertent consequence of an earlier bug fix). (Bug

#25244898, Bug #84173)

• Semicolon (;) characters within or between statements could cause distinct digests to be generated from

identical statements. (Bug #25244533, Bug #83253)

• For a client linked against libmysqlclient, invalid memory access could occur during use of

prepared statements. (Bug #25164932)

• The fix for Bug #25088048 caused the command used by mysqld_safe to start the MySQL server to

no longer include the mysqld path. (Bug #25144379)

References: This issue is a regression of: Bug #25088048.

• Executing a stored procedure containing a query that accessed a view could allocate memory that was

not freed until the session ended. (Bug #25053286)

• A query could produce incorrect results if the WHERE clause contained a dependent subquery, the table

had a secondary index on the columns in the select list followed by the columns in the subquery, and

GROUP BY or DISTINCT permitted the query to use a Loose Index Scan. (Bug #24671968, Bug #83005)

• Creation of a MyISAM temporary table during query processing could fail if the key length in the query

was greater than the maximum MyISAM key length, resulting in a server exit. (Bug #24659861)

• The DebugPrintTest and DebugPrintDeathTest unit tests did not handle divide-by-zero testing

properly on the Aarch64 platform. Thanks to Alexey Kopytov for the patch. (Bug #24624555, Bug

#82889)

• Changes made to mysqld_safe in recent MySQL releases require the --ledir, --mysqld, --

mysqld-version options to be specified on the command line; they can no longer be specified in

option files. This could cause failure of init scripts that invoke mysqld_safe. Such scripts now pass the

value of the MYSQLD_OPTS environment variable as the first command-line argument to mysqld_safe,

with the value set to such command line-only mysqld_safe option values as may be required. On

platforms that use systemd, the MYSQLD_OPTS value can be set in /etc/sysconfig/mysqld with a

line such as this:

MYSQLD_OPTS=" --ledir=/mysqld_ledir --mysqld=my_wrapper "

The value of MYSQLD_OPTS can also include mysqld options for mysqld_safe to pass to mysqld.

(Bug #24619033, Bug #82920)

References: This issue is a regression of: Bug #24464380, Bug #24483092, Bug #25088048, Bug

#25378439, Bug #25378565.

• For LOAD DATA used to insert data into an updateable view, the check to verify whether a column is

actually updatable was missing. (Bug #24595937)

• On Debian/Ubuntu platforms, the systemd startup script for MySQL ignored datadir settings in /etc/

mysql/my.cnf. (Bug #24517024, Bug #82709)

• A regular expression pattern match into a large string could result in a server exit due to memory

allocation failure or integer overflow. (Bug #24449076, Bug #24449090)

• An incorrect error was reported for CREATE TABLE statements with a large value for the CONNECTION

table option. The value is now limited to 1024 bytes. (Bug #24437124)

MySQL 5.6 Release Notes

• MySQL now uses readdir() rather than readdir_r(). The latter has been deprecated since glibc

2.24 and caused debug builds of MySQL and builds using GCC 6.1 to fail.

Additionally, several problems resulting in GCC 6.1 compiler warnings were corrected. (Bug #23708395,

Bug #24437737, Bug #82515, Bug #24459890, Bug #82583, Bug #25103242)

• The -DWITH_EDITLINE=system CMake option failed with recent versions of the editline library.

(Bug #23708332, Bug #25391997, Bug #84501)

• Grant tables with incorrect structure may cause problems in user management operations. As a

consequence of the fix for this, for any operation that modifies a grant table, the server now checks

whether the table has the expected structure and produces an error if not. mysql_upgrade must be run

to update the tables to the expected structure. (Bug #23295423, Bug #25095876, Bug #25448037)

• The QUOTE() function could allocate excessive memory. A limit of max_allowed_packet bytes is now

imposed and returns NULL with a warning for attempts to allocate more. (Bug #23195404)

• When attempting to locate the data directory, mysqld_safe incorrectly considered

$MY_BASEDIR_VERSION/var as one of the possible locations. (Bug #23013510, Bug #80866)

• The main.log_tables-big test case could be unstable on highly loaded hosts. Thanks to Laurynas

Biveinis for the patch. (Bug #22874167, Bug #80607)

• Queries that used an aggregate function with DISTINCT could produce incorrect results. (Bug

#22686994, Bug #80310)

• With the use_index_extensions flag of the optimizer_switch system variable disabled, some

SELECT DISTINCT queries could return incorrect results. (Bug #21749123, Bug #78244)

• Debian packages were missing an AppArmor-related include file and incorrectly were marked dependent

on AppArmor (making it impossible to disable AppArmor by uninstalling it). (Bug #20768958)

• In a replication environment, SET PASSWORD or ALTER USER could fail to execute on the slave due to

failure to parse the hash string correctly. (Bug #20228478)

• On non-Linux Unix systems, the mysql.server startup script used the Linux command pidof rather

than pgrep. (Bug #13788154, Bug #64342)

• Starting multiple instances of mysqld_safe after an abnormal server exit could result in one

mysqld_safe instance killing another. As a consequence of the bug fix, the mysqld_safe.pid file is

no longer used. (Bug #11751149, Bug #41908)

• The --help message for mysqld_safe was corrected to mention that the --no-defaults, --

defaults-file, and --defaults-extra-file options, if given, must be the first argument. (Bug

#11745176, Bug #11192)

• The bounds check for the XML parser position stack for each level (which has a fixed depth) used the

size of the array as the upper limit, and so was off by one. This is fixed by decreasing the allowable

depth by one, which actually matches the maximum number of elements in the position stack. (Bug

#83871, Bug #25111907)

References: See also: Bug #14040071, Bug #15948580.

• Timestamps for server-side prepared statements could be written to the binary log up to a second behind

timestamps for the corresponding nonprepared statements, leading to time value differences between

master and slave servers. (Bug #74550, Bug #19894382, Bug #25187670)

Changes in MySQL 5.6.35 (2016-12-12, General Availability)

MySQL 5.6 Release Notes

• Connection Management Notes

• MySQL Enterprise Notes

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

Connection Management Notes

• MySQL Server now includes a plugin library that enables administrators to introduce an increasing delay

in server response to clients after a certain number of consecutive failed connection attempts. This

capability provides a deterrent that slows down brute force attacks that attempt to access MySQL user

accounts. For more information, see The Connection-Control Plugins. (WL #8885)

MySQL Enterprise Notes

• Enterprise Encryption for MySQL Enterprise Edition now enables server administrators to impose limits

on maximum key length by setting environment variables. These can be used to prevent clients from

using excessive CPU resources by passing very long key lengths to key-generation operations. For

more information, see MySQL Enterprise Encryption Usage and Examples. (Bug #19687742)

Security Notes

• Incompatible Change: These changes were made to mysqld_safe:

• Unsafe use of rm and chown in mysqld_safe could result in privilege escalation. chown now can be

used only when the target directory is /var/log. An incompatible change is that if the directory for

the Unix socket file is missing, it is no longer created; instead, an error occurs. Due to these changes,

/bin/bash is required to run mysqld_safe on Solaris. /bin/sh is still used on other Unix/Linux

platforms.

• The --ledir option now is accepted only on the command line, not in option files.

• mysqld_safe ignores the current working directory.

Other related changes:

• Initialization scripts that invoke mysqld_safe pass --basedir explicitly.

• Initialization scripts create the error log file only if the base directory is /var/log or /var/lib.

• Unused systemd files for SLES were removed.

(Bug #24483092, Bug #25088048, Bug #25378439, Bug #25378565)

References: See also: Bug #24464380, Bug #24388753, Bug #24619033, Bug #82920.

• OpenSSL is ending support for version 1.0.1 in December 2016; see https://www.openssl.org/policies/

releasestrat.html. Consequently, MySQL Commercial Server builds now use version 1.0.2 rather

than version 1.0.1, and the linked OpenSSL library for the MySQL Commercial Server has been

updated from version 1.0.1 to version 1.0.2j. For a description of issues fixed in this version, see https://

www.openssl.org/news/vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (WL #9136)

MySQL 5.6 Release Notes

Functionality Added or Changed

• InnoDB: By default, InnoDB reads uncommitted data when calculating statistics. In the case of

an uncommitted transaction that deletes rows from a table, InnoDB excludes records that are

delete-marked when calculating row estimates and index statistics, which can lead to non-optimal

execution plans for other transactions that are operating on the table concurrently using a transaction

isolation level other than READ UNCOMMITTED. To avoid this scenario, a new configuration option,

innodb_stats_include_delete_marked, can be enabled to ensure that InnoDB includes delete-

marked records when calculating persistent optimizer statistics. (Bug #23333990)

• Unit testing now uses Google Mock 1.8. (Bug #24572381, Bug #82823)

Bugs Fixed

• Incompatible Change: A change made in MySQL 5.6.32 for handling of multibyte character sets by

LOAD DATA was reverted due to the replication incompatibility (Bug #24487120, Bug #82641)

References: See also: Bug #23080148.

• InnoDB: The GCC mach_parse_compressed function should load one to five bytes depending on the

value of the first byte. Due to a GCC bug, GCC 5 and 6 emit code to load four bytes before the first byte

value is checked (GCC Bug #77673). A workaround prevents this behavior. Thanks to Laurynas Biveinis

for the patch. (Bug #24707869, Bug #83073)

• InnoDB: Due to a glibc bug, short-lived detached threads could exit before the caller had returned

from pthread_create(), causing a server exit. Thanks to Laurynas Biveinis for the patch. (Bug

#24605956, Bug #82886)

• InnoDB: An error during a table-rebuilding operation on a table with only a generated clustered index

(GEN_CLUST_INDEX) raised and assertion due to an error called with an invalid key name. (Bug

#24444831)

• InnoDB: On a table without an explicitly defined primary key, InnoDB did not replace the implicit

clustered index (GEN_CLUST_INDEX) when a unique key was defined on a NOT NULL column. (Bug

#24397406)

• InnoDB: InnoDB failed to free memory used by the full-text optimizer thread. (Bug #24331265)

• InnoDB: SHOW ENGINE INNODB STATUS output showed a “cleaning up” state for an idle thread.

Thread state information was not reset after statement execution. (Bug #21974225, Bug #78777)

• InnoDB: After a server restart, concurrent INSERT operations a table with an auto-increment primary

key resulted in a duplicate entry error. The current auto-increment value was not changed after

auto_increment_increment and auto_increment_offset settings were modified. (Bug

#20989615, Bug #76872)

• Replication: Tables with special DEFAULT columns, such as DEFAULT CURRENT_TIMESTAMP,

that existed only on a slave were not being updated when using row-based replication

(binlog_format=ROW). (Bug #22916743)

• Replication: Enabling semisynchronous replication when a server was during the commit stage could

cause the master to stop unexpectedly. This was related to the patch for Bug# 75570. (Bug #22202516)

• Replication: The fix for Bug #81657 was not correctly merged into MySQL 8.0. Thanks to Laurynas

Biveinis for alerting us. (Bug #83124, Bug #24715790)

• Some Linux startup scripts did not process the datadir setting correctly. (Bug #25159791)

MySQL 5.6 Release Notes

• CREATE TABLE now requires the FILE privilege if DATA DIRECTORY or INDEX DIRECTORY is

specified explicitly as a table or partition option. ALTER TABLE requires the FILE privilege if either

option is specified explicitly as a partition option (it ignores them if specified as table options). (Bug

#25092566)

• OEL RPM packages now better detect which platforms have multilib support (for which 32-bit and 64-bit

libraries can be installed). Thanks to Alexey Kopytov for the patch. (Bug #24925181, Bug #83457)

• Compiling MySQL using Microsoft Visual Studio 2015 Version 14.0.25420.1 in relwithdebinfo mode

failed with linking errors. (Bug #24748505)

• Warnings occurring during CREATE TABLE ... SELECT could cause a server exit. (Bug #24595992)

• For segmentation faults on FreeBSD, the server did not generate a stack trace. (Bug #24566529, Bug

#23575445, Bug #81827)

• The .mylogin.cnf option file is intended for use by client programs, but the server was reading it as

well. The server no longer reads it. (Bug #24557925)

• If mysqladmin shutdown encountered an error determining the server process ID file, it displayed

an error message that did not clearly indicate the error was nonfatal. It now indicates that execution

continues. (Bug #24496214)

• The data structure used for ZEROFILL columns could experience memory corruption, leading eventually

to a server exit. (Bug #24489302)

• Use of very long subpartition names could result in a server exit. Now partition or subpartition names

larger than 64 characters produce an ER_TOO_LONG_IDENT error. (Bug #24400628, Bug #82429)

• On Solaris, gettimeofday() could return an invalid value and cause a server shutdown. (Bug

#23499695)

• A union query resulting in tuples larger than max_join_size could result in a server exit. (Bug

#23303485)

• The optimizer could choose ref access on a secondary index rather than range access on the primary

key, even when the cost was higher. (Bug #23259872, Bug #81341)

• For some deeply nested expressions, the optimizer failed to detect stack overflow, resulting in a server

exit. (Bug #23135667)

• When taking the server offline, a race condition within the Performance Schema could lead to a server

exit. (Bug #22551677)

• The Performance Schema events_statements_summary_by_digest table could contain multiple

rows for the same statement digest and schema combination, rather than the expected single (unique)

row. (Bug #22320066, Bug #79533)

• For debug builds: Adding a unique index to a POINT NOT NULL column triggered a warning and the key

was not promoted to a primary key. Creating a unique index on a different non-NULL column in the same

table then raised an assertion. (Bug #19635706, Bug #24469860)

• Compiling using Clang 3.5 or higher with AddressSanitizer (ASAN) enabled caused the gen_lex_hash

utility to abort on Clang LeakSanitizer memory leak check failures. (Bug #76351, Bug #20720615, Bug

#22558597, Bug #80014)

• Miscalculation of memory requirements for qsort operations could result in stack overflow errors in

situations with a large number of concurrent server connections. (Bug #73979, Bug #19678930, Bug

#23224078)

MySQL 5.6 Release Notes

Changes in MySQL 5.6.34 (2016-10-12, General Availability)

• Packaging Notes

• Security Notes

Packaging Notes

• RPM and Debian packages now create the /var/lib/mysql-files directory, which is now the

default value of the secure_file_priv system variable that specifies a directory for import and export

operations. (Bug #24709892, Bug #24761774)

Security Notes

• Incompatible Change: The secure_file_priv system variable is used to limit the effect of data

import and export operations. The following changes have been made to how the server handles this

variable:

• secure_file_priv can be set to NULL to disable all import and export operations.

• The server checks the value of secure_file_priv at startup and writes a warning to the error log

if the value is insecure. A non-NULL value is considered insecure if it is empty, or the value is the data

directory or a subdirectory of it, or a directory that is accessible by all users. If secure_file_priv is

set to a nonexistent path, the server writes an error message to the error log and exits.

• Previously, the secure_file_priv system variable was empty by default. Now the default value is

platform specific and depends on the value of the INSTALL_LAYOUT CMake option, as shown in the

following table.

INSTALL_LAYOUT Value Default secure_file_priv Value

STANDALONE, WIN NULL

DEB, RPM, SLES, SVR4 /var/lib/mysql-files

Otherwise mysql-files under the

CMAKE_INSTALL_PREFIX value

• To specify the default secure_file_priv value explicitly if you are building from source, use the

new INSTALL_SECURE_FILE_PRIVDIR CMake option. To specify a directory for the embedded

server, set the new INSTALL_SECURE_FILE_PRIV_EMBEDDEDDIR option. Its default value is NULL.

(Bug #24679907, Bug #24695274, Bug #24707666, WL #6782)

• The linked OpenSSL library for the MySQL Commercial Server has been updated to version 1.0.1u. For

a description of issues fixed in this version, see http://www.openssl.org/news/vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #24753389)

• yaSSL was upgraded to version 2.4.2. This upgrade corrects issues with: Potential AES side channel

leaks; DSA padding for unusual sizes; the SSL_CTX_load_verify_locations() OpenSSL

compatibility function failing to handle long path directory names. (Bug #24512715, Bug #24740291)

Changes in MySQL 5.6.33 (2016-09-06, General Availability)

• Compilation Notes

MySQL 5.6 Release Notes

• Test Suite Notes

• Bugs Fixed

Compilation Notes

• CMake support was added for compiling with Developer Studio 12.5. (Bug #82249, Bug #24303829, Bug

#81274, Bug #23212938)

Test Suite Notes

• In mysql-test-run.pl, a limit of 50 was imposed on the number of workers for parallel testing, which

on systems with more than 50 CPUs resulted in exhaustion of unique thread IDs. The ID-exhaustion

problem has been corrected, and the limit of 50 on number of workers has been lifted. Thanks to Daniel

Black for the patch on which this change was based. Additionally, these changes were made:

• To avoid idle workers, the number of parallel workers now is limited to the number of tests.

• Previously, if --parallel=auto was given and the MTR_MAX_PARALLEL environment variable was

not set, a limit of 8 was imposed on the number of parallel workers. This limit has been lifted.

(Bug #22342399, Bug #79585)

Bugs Fixed

• InnoDB: An operation that dropped and created a full-text search table raised an assertion. (Bug

#24315031)

• InnoDB: Accessing full-text search auxiliary tables while dropping the indexed table raised an assertion.

(Bug #24009272)

• InnoDB: An online DDL operation on a table with indexed BLOB columns raised an assertion during

logging of table modifications. (Bug #23760086)

• Replication: mysqlbinlog --read-from-remote-server log1 log2 was opening a new

connection for log2 without freeing the connection used for log1. Thanks to Laurynas Biveinis for the

contribution. (Bug #81675, Bug #23540182)

• Replication: With binlog_row_image=FULL, when updating single tables temporary tables were

unnecessarily being used. The fix ensures single table update follows the same pattern as multi-table

update. (Bug #79867, Bug #22510353)

• For mysqld_safe, the argument to --malloc-lib now must be one of the directories /usr/lib, /

usr/lib64, /usr/lib/i386-linux-gnu, or /usr/lib/x86_64-linux-gnu. In addition, the --

mysqld and --mysqld-version options are accepted only on the command line, not in option files.

(Bug #24464380)

References: See also: Bug #24619033, Bug #82920.

• It was possible to write log files ending with .ini or .cnf that later could be parsed as option files. The

general query log and slow query log can no longer be written to a file ending with .ini or .cnf. (Bug

#24388753)

• Privilege escalation was possible by exploiting the way REPAIR TABLE used temporary files. (Bug

#24388746)

• If the basedir system variable was set at server startup from the command line or option file, the value

was not normalized (on Windows, / was not replaced with \). (Bug #23747899, Bug #82125)

MySQL 5.6 Release Notes

• In-place ALTER TABLE operations which when executed separately caused no table rebuild could when

combined into a single statement result in a table rebuild. (Bug #23475211, Bug #81587)

• A blank server name in CREATE SERVER statements produced a server exit rather than an error. (Bug

#23295288)

• A prepared statement that used a parameter in the select list of a derived table that was part of a join

could cause a server exit. (Bug #22392374, Bug #24380263)

• MEDIUMINT columns used in operations with long integer values could result in buffer overflow. (Bug

#19984392)

• A spurious ER_NO_SUCH_TABLE error could occur when attempting to execute a prepared CREATE

TABLE ... SELECT statement that used a temporary table in the FROM clause and called a stored

function. The same error could occur for a nonprepared version of the statement if used in a stored

procedure when the procedure was re-executed. (Bug #16672723, Bug #68972)

• EINTR handling in the client library has been fixed so that interrupted read and write calls are retried.

Previously, EINTR was ignored. (Bug #82019, Bug #23703570)

Changes in MySQL 5.6.32 (2016-07-29, General Availability)

Bugs Fixed

• Incompatible Change: For multibyte character sets, LOAD DATA could fail to allocate space correctly

and ignore input rows as a result.

A consequence of this change is that previously accepted invalid character data is now rejected, which

can cause issues if you replicate from an older server without this bug fix to a newer server with this bug

fix. For example, if an older server that accepts invalid utf8 character set data replicates to a newer

server with this bug fix, the newer server will not accept the data and replication will fail with an “Invalid

utf8 character string” error. Solutions for this issue include:

• Correct the invalid data so that it is correct for the character set

• Use a different character set for which the data is not invalid

• Upgrade the master to a version that has the bug fix so that master and slave interpret the data the

same way

(Bug #76237, Bug #20683959, Bug #23080148)

References: This issue is a regression of: Bug #14653594.

• InnoDB: Full-text search auxiliary tables could be dropped by one session while being access by

another. (Bug #23742339)

• InnoDB: Selecting full-text index information schema tables for a deleted table caused a segmentation

fault. (Bug #23479595)

• InnoDB: Rollback of a full-text index synchronization operation raised an assertion. The rollback

operation attempted to acquire a mutex still held by the background synchronization thread. (Bug

#23320569)

• InnoDB: Setting innodb_monitor_enable to all did not enable all counters. (Bug #22576241, Bug

#80083)

MySQL 5.6 Release Notes

• Replication: An incorrectly formed server_uuid read in from auto.conf could cause an unexpected

halt. (Bug #21936933)

• Replication: After issuing a PURGE BINARY LOGS statement, if the binary log index file was not

available, for example because it had been opened by another application such as MEB, the server

could stop unexpectedly. Although this situation was rare, the handling has been made more robust to

avoid unexpected halts and more informative errors are provided. (Bug #20381055)

• Replication: When using row-based replication and InnoDB, replication slaves reverted to using an

older locking scheme when a transaction had already acquired an AUTOINC lock related to a LOAD

FILE or INSERT ... SELECT type of statement, reducing replication slave performance. The fix

ensures that sql_command is set correctly for any of the DML events such as WRITE_ROWS_EVENT,

UPDATE_EVENT, and DELETE_EVENT. (Bug #79324, Bug #22247668)

• Replication: A MySQL version 5.5 slave does not have a server_uuid and replication identified

servers by their server_id. Starting from MySQL version 5.6, replication masters detected a zombie

dump thread based only on a slave's server_uuid value, under the assumption that each slave has

a unique UUID. Connecting a MySQL 5.5 slave to a MySQL 5.6 and later master meant that the master

was unable to detect zombie dump threads that were created to serve slaves running versions older than

MySQL 5.6. The fix ensures that a master now first checks if a slave has a server_uuid set. If it is set,

zombie dump thread detection happens based on the slave's UUID. If a slave's server_uuid is not set,

zombie dump thread detection happens based on server_id. (Bug #77195, Bug #21179199)

• Replication: With slave_skip_errors enabled there were still special cases when slave errors were

not being correctly ignored. For example:

• When opening and locking a table failed.

• When field conversions failed on a server running row-based replication.

In these cases the error was considered critical and it was not respecting the state of

slave_skip_errors. The fix ensures that with slave_skip_errors enabled, all errors reported

during applying a transaction are correctly handled. This means that in such a set up, upon receiving an

error with the log_warnings option set to greater than 1, if the error can be ignored then the warning

is printed into the error log and the server continues as it does in the case of other ignored errors. (Bug

#70640, Bug #17653275)

• Replication: When using statement-based or mixed binary logging format with --read-only=ON, it

was not possible to modify temporary tables. (Bug #62008, Bug #12818255)

References: See also: Bug #14294223, Bug #16561483.

• MySQL Server upgrades performed using RPM packages failed when upgrading from MySQL 5.5

Community to MySQL 5.6 Community or MySQL 5.5 Commercial to MySQL 5.6 Commercial. (Bug

#23736787)

• The code for reading character set information from Performance Schema statement events tables (for

example, events_statements_current) did not prevent simultaneous writing to that information. As

a result, the SQL query text character set could be invalid, which could result in a server exit. Now an

invalid character set causes SQL_TEXT column truncation. (Bug #23540008)

• A buffer overflow in the regex library was fixed. (Bug #23498283)

• Certain arguments to NAME_CONST() could cause a server exit. (Bug #23279858)

• For unit-testing with the MySQL test suite, the make unit-test command is no longer available. The

ctest program should be used instead. See the MySQL Server Doxygen documentation, available at

https://dev.mysql.com/doc/index-other.html. (Bug #23273434, Bug #81389)

MySQL 5.6 Release Notes

• ST_Distance() could raise an assertion for NULL return values. (Bug #22760390)

• With the query cache enabled, executing a prepared statement with CURSOR_TYPE_READ_ONLY and

then again with CURSOR_TYPE_NO_CURSOR caused the server to return an error. (Bug #22559575, Bug

#80026)

• mysql_real_connect() was not thread-safe when invoked with the MYSQL_READ_DEFAULT_FILE

or MYSQL_READ_DEFAULT_GROUP option enabled. (Bug #22322504, Bug #79510)

• Installing MySQL from a yum or zypper repository resulted in /var/log/mysqld.log being created

with incorrect user and group permissions. (Bug #21879694, Bug #78512)

• If a stored function updated a view for which the view table had a trigger defined that updated another

table, it could fail and report an error that an existing table did not exist. (Bug #21142859, Bug #76808)

• If an INSTALL PLUGIN statement contained invalid UTF-8 characters in the shared library name, it

caused the server to hang (or to raise an assertion in debug builds). (Bug #14653594, Bug #23080148,

Bug #27167197)

Changes in MySQL 5.6.31 (2016-06-02, General Availability)

• Packaging Notes

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

Packaging Notes

• support-files/MacOSX/ReadMe.txt is no longer included in MySQL distributions. (Bug #81038,

Bug #23088916)

• The INSTALL-SOURCE file had partly outdated information and has been removed from source

packages. (Binary packages are unaffected). (Bug #80680, Bug #23081064)

Security Notes

• The linked OpenSSL library for the MySQL Commercial Server has been updated to version 1.0.1t. For a

description of issues fixed in this version, see http://www.openssl.org/news/vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #23229564)

Functionality Added or Changed

• A new CMake option, WITH_SYMVER16, if enabled, causes the libmysqlclient client library

to contain extra symbols to be compatible with libmysqlclient on RHEL/OEL 5, 6, 7, and

Fedora releases. All symbols present in libmysqlclient.so.16 are tagged with symver 16 in

libmsqlclient.so.18, making those symbols have both symver 16 and 18. (Bug #22980983)

• The version of the tcmalloc library included in MySQL distributions was very old. It has been removed

and is no longer included with MySQL. (Bug #80994, Bug #23068660)

Bugs Fixed

• InnoDB: MySQL failed to build on Fedora 24 using GCC 6. (Bug #23227804)

MySQL 5.6 Release Notes

• InnoDB: Potential buffer overflow issues were corrected for the InnoDB memcached plugin. (Bug

#23187607)

• InnoDB: The full-text index cache was freed during a background index cache synchronization. (Bug

#22996488)

• InnoDB: A full-text index operation raised an assertion. (Bug #22963169)

• InnoDB: An INSERT operation on a table with a FULLTEXT index and FTS_DOC_ID column

failed because the inserted FTS_DOC_ID value exceeded the permitted gap between consecutive

FTS_DOC_ID values. To avoid this problem, the permitted gap between the largest used FTS_DOC_ID

value and new FTS_DOC_ID value was raised from 10000 to 65535. (Bug #22679185)

• InnoDB: With innodb_autoinc_lock_mode=0, multiple threads waiting for a table-level lock caused

an unexpected deadlock. (Bug #21983865, Bug #78761)

• InnoDB: A FLUSH TABLES ... FOR EXPORT operation appeared to stall. A loop in the

ibuf_contract_in_background function failed to exit. (Bug #21133329, Bug #77011)

• InnoDB: A full-text query raised an assertion. Under certain circumstances, DDL operations such as

ALTER TABLE ... RENAME caused full-text auxiliary tables to be removed on server restart. (Bug

#13651665)

• Replication: In the next_event() function, which is called by a slave's SQL thread to read the next

even from the relay log, the SQL thread did not release the relaylog.log_lock it acquired when it

ran into an error (for example, due to a closed relay log), causing all other threads waiting to acquire a

lock on the relay log to hang. With this fix, the lock is released before the SQL thread leaves the function

under the situation. (Bug #21697821)

References: See also: Bug #20492319.

• Replication: When using row-based replication in a cascading or circular replication setup, where

a master is replicating to server 1 which is then replicating to server 2, merge tables were not being

correctly applied on server 2. This could cause an unexpected halt on server 2 while server 1 was

unaffected. (Bug #17018343)

• Replication: If a multithreaded replication slave running with relay_log_recovery=1 stopped

unexpectedly, during restart the relay log recovery process could fail. This was due to transaction

inconsistencies not being filled, see Handling an Unexpected Halt of a Replica Server. Prior to this fix,

to recover from this situation required manually setting relay_log_recovery=0, starting the slave

with START SLAVE UNTIL SQL_AFTER_MTS_GAPS to fix any transaction inconsistencies and then

restarting the slave with relay_log_recovery=1. This process has now been automated, enabling

relay log recovery of a multithreaded slave upon restart automatically. (Bug #77496, Bug #21507981)

• Microsoft Windows: On Windows, MySQL installation could result in MySQL being placed under C:

\Program Files\Canon\Easy-WebPrint EX. (Bug #14583183)

References: See also: Bug #70918, Bug #68821, Bug #68227.

• Microsoft Windows: On Windows, MySQL installation failed if the HKEY_LOCAL_MACHINE\SOFTWARE

\Microsoft\Windows\CurrentVersion\Uninstall\ registry key was present with a key/value

pair of "InstallLocation" and "\Hewlett-Packard\\". (Bug #74631, Bug #19949163)

• INSERT with ON DUPLICATE KEY UPDATE and REPLACE on a table with a foreign key constraint

defined failed with an incorrect duplicate entry error rather than a foreign key constraint violation

error. (Bug #23135731)

References: This issue is a regression of: Bug #78853, Bug #22037930.

MySQL 5.6 Release Notes

• For debug builds, CONCAT_WS() could raise an assertion if there was nothing to append. (Bug

#22888420)

• Invoking Enterprise Encryption functions in multiple threads simultaneously could cause a server exit.

(Bug #22839278)

• Attempting to use Enterprise Encryption functions after creating and dropping them could cause a server

exit. (Bug #22669012)

• Setting sort_buffer_size to a very large value could cause some operations to fail with an out-of-

memory error. (Bug #22594514)

• An assertion could be raised when a deadlock occurred due to a SELECT ... GROUP BY ... FOR

UPDATE query executed using a Loose Index Scan. (Bug #22187476)

• Several potential buffer overflow issues were corrected. (Bug #21977380, Bug #23187436, Bug

#23202778, Bug #23195370, Bug #23202699)

• If the CA certificate as given to the --ssl-ca option had an invalid path, yaSSL returned

an error message different from OpenSSL. Now both return SSL connection error:

SSL_CTX_set_default_verify_paths failed. (Bug #21920657)

• Some string functions returned one or a combination of their parameters as their result. If one of the

parameters had a non-ASCII character set, the result string had the same character set, resulting in

incorrect behavior when an ASCII string was expected. (Bug #18740222)

• On Fedora 24, upgrades using a Community MySQL Server RPM failed to replace an installed MariaDB

Galera server due to a change in the MariaDB package. (Bug #81390, Bug #23273818)

• MySQL did not compile under Solaris 12 using Sun Studio. To correct this, instances of

__attribute__ were changed to MY_ATTRIBUTE. (Bug #80748, Bug #22932576)

• For a server compiled with -DWITH_PERFSCHEMA_STORAGE_ENGINE=0, a memory leak could occur for

buffered log messages used during server startup. (Bug #80089, Bug #22578574)

• For debug builds, merging a derived table into an outer query block could raise an assertion. (Bug

#79502, Bug #22305361, Bug #21139722)

• A null pointer dereference of a parser structure could occur during stored procedure name validation.

(Bug #79396, Bug #22286421)

• Using CREATE USER to create an account with the mysql_native_password or

mysql_old_password authentication plugin and using a clause of the form IDENTIFIED WITH

plugin AS 'hash_string' caused the account to be created without a password. (Bug #78033, Bug

#21616496)

• Failure of UNINSTALL PLUGIN could lead to inaccurate or confusing errors for subsequent INSTALL

PLUGIN operations. (Bug #74977, Bug #20085672)

• mysqld_multi displayed misleading error messages when it was unable to execute

my_print_defaults. (Bug #74636, Bug #19920049)

• mysqldump failed silently with no error message when it encountered an error while executing FLUSH

LOGS. (Bug #71783, Bug #18284273)

Changes in MySQL 5.6.30 (2016-04-11, General Availability)

• Security Notes

MySQL 5.6 Release Notes

• Bugs Fixed

Security Notes

• The linked OpenSSL library for the MySQL Commercial Server has been updated to version 1.0.1s. For

a description of issues fixed in this version, see http://www.openssl.org/news/vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #22685885, Bug #22923458)

• MySQL client programs now support an --ssl-mode option that enables you to specify the security

state of the connection to the server. If the option is not specified, the default value is DISABLED

(establish an unencrypted connection). --ssl-mode=REQUIRED can be specified to require an

encrypted connection, or fail if an encrypted connection cannot be obtained.

These clients support --ssl-mode: mysql, mysqladmin, mysqlcheck, mysqldump, mysqlimport,

mysqlshow, mysqlpump, mysqlslap, mysqltest, mysql_upgrade.

For more information, see Command Options for Encrypted Connections.

Note

In MySQL 5.7 and higher, the C client library provides native support for requiring

encrypted connections: call the mysql_options() C API function, passing the

MYSQL_OPT_SSL_MODE option with a value of SSL_MODE_REQUIRED. In MySQL

8.0, the client library provides no such support because doing so would break

binary compatibility with previous library versions within the series. Clients that

require encrypted connections must implement the logic themselves.

To require encrypted connections in MySQL 8.0, the standard MySQL client

programs use this technique: If --ssl-mode=REQUIRED was specified, the

client program turns on SSL, connects to the server, and checks whether the

resulting connection is encrypted. If not, the client exits with an error. Third-party

applications that must be able to require encrypted connections can use the

same technique. For details, see mysql_ssl_set().

(WL #8785, WL #9072)

Bugs Fixed

• InnoDB; Partitioning: When OPTIMIZE TABLE rebuilt a partitioned InnoDB table, it placed the

resulting partition tablespace files (*.ibd files) in the default data directory instead of the directory

specified using the DATA DIRECTORY option. (Bug #75112, Bug #20160327)

• InnoDB: Running REPLACE operations on multiple connections resulted in a hang. (Bug #22530768,

Bug #79185)

• InnoDB: MySQL stalled when synchronizing the InnoDB full-text index cache. (Bug #22516559, Bug

#16510576, Bug #73816)

• InnoDB: A CREATE TABLE ... DATA DIRECTORY operation failed to create a table while

innodb_flush_method was set to O_DIRECT. (Bug #22180006, Bug #79200)

References: This issue is a regression of: Bug #21113036.

• InnoDB: The innodb_open_files setting could exceed the open files limit. (Bug #22111472)

MySQL 5.6 Release Notes

• Replication: Issuing STOP SLAVE caused a spurious Error reading packet from server:

Lost connection to MySQL server during query message to be written to the error log. With

this fix, when connection to the master is lost, the abort_slave flag is checked and the error message

is printed only if the flag is not set. (Bug #22305605, Bug #79504)

References: See also: Bug #12977988, Bug #22290309.

• Replication: When a multithreaded slave stopped with an error, the same error message was printed

three times. Now, the SQL thread's kill acceptance status is saved, and only printed once. (Bug

#21198611, Bug #77237)

• Replication: mysqlbinlog --verbose displayed BINARY and VARBINARY data as ordinary

strings, causing any single quote (“'”) or backslash (“\”) among the data to be printed as such, which was

confusing to the users and, in the case of a backslash, caused the next character to be skipped. This

fix makes mysqlbinlog print the characters' hexadecimal values (“\x27” for single quote and “\x5c” for

backslash) instead. (Bug #20836250)

• Replication: The test case main.merge failed when the variables binlog_format was set to “ROW,”

as the server tried to get information for table creation for a child table before it was opened. With this fix,

the server skips getting information for the table in the situation. (Bug #20574550, Bug #75976)

• Replication: If a query on a master generated an error and partial results were written to the binary log,

for example due to a DROP TABLE IF EXISTS statement applying to multiple tables that would break

foreign key constraints, when a slave configured with replication filters encountered the query it could be

incorrectly binary logged. This caused errors such as:

Last_SQL_Error: Query caused different errors on master and slave. Error on

master: message (format)='Cannot delete or update a parent row: a foreign

key constraint fails' error code=1217 ; Error on slave: actual message='no

error', error code=0. Default database: 'db1'. Query: 'DROP TABLE IF EXISTS

`table1` /* generated by server */'

There were two fixes required for this bug.

• If a DROP TABLE statement used to drop a single table fails, to avoid partial results causing this bug

the query is not written to the binary log. If a DROP TABLE statement used to drop a list of tables fails,

any partial results it generates are written to the binary log with an error.

• When a query that generates an error as expected was received by a slave but it was skipped due

to replication filters, the slave was incorrectly checking the error. The fix for Bug #76493 ensures that

this comparison of the expected error from the master with the actual error from the slave does not

happen.

(Bug #77684, Bug #21435502)

References: See also: Bug #20797764, Bug #76493.

• Integer overflow could occur during client handshake processing, leading to a server exit. (Bug

#22722946)

• The System-V initialization script for RHEL6 or older failed to enable the mysqld service by default. (Bug

#22600974)

• When ExtractValue() found no match for the supplied expression, it returned NULL instead of an

empty string as expected.

This issue affected MySQL 5.6.28 and 5.6.29 only. (Bug #22552615)

MySQL 5.6 Release Notes

• Improper host name checking in X509 certificates could permit man-in-the-middle attacks. (Bug

#22295186, Bug #22738607)

• A boolean mode full-text search caused a segmentation fault. (Bug #22176795)

• Concurrent selecting and flushing of a FEDERATED table while killing connections accessing it could

result in a server exit. (Bug #21918190)

• Executing GRANT PROXY statements after altering the definition of the mysql.user system table could

result in a server exit. (Bug #21699037)

• Certain error messages included part of the SQL statement that produced them, possibly exposing data.

(Bug #21682356)

• Although it is possible to create nontemporary tables using the prefix #sql, Performance Schema

assumed that tables named using this prefix were temporary and could be ignored. Performance

Schema now uses table attributes other than the name to identify temporary tables. (Bug #21105475,

Bug #22532368, Bug #79934)

• Account filtering performed by the audit_log plugin incorrectly used the account named by the

USER() function rather than the CURRENT_USER() function (the latter being the account used for

authentication). (Bug #19509471, Bug #22454245, Bug #77553)

• Character set conversion operations on NULL parameters to prepared statements could cause a server

exit. (Bug #18823979)

• Loose Index Scan was not chosen for queries that had an equality condition. (Bug #18109609)

• A MySQL 5.6 server exited during startup if used with a 5.7 data directory due to the change in 5.7 of the

mysql.plugin table from MyISAM to InnoDB. A safe shutdown now occurs in this circumstance. (Bug

#79290, Bug #22216779)

• For INSERT and UPDATE operations that caused FOREIGN KEY constraint violations, errors were

reported rather than warnings when the IGNORE keyword was used. (Bug #78853, Bug #22037930)

References: See also: Bug #23135731.

• For some queries, an Index Merge access plan was chosen over a range scan when the cost for the

range scan was the same or less. (Bug #77209, Bug #21178196)

• Certain queries could raise an assertion when a internal string operation produced a NULL pointer rather

than an empty string. (Bug #74500, Bug #19875294, Bug #13358486, Bug #79988, Bug #22551116)

• EXPLAIN for SELECT ... FOR UPDATE statements acquired locks. (Bug #72858, Bug #18899860)

• Processlist state information was not updated correctly for LOAD DATA and could show a state different

from executing. (Bug #69375, Bug #16912362)

Changes in MySQL 5.6.29 (2016-02-05, General Availability)

• Packaging Notes

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

MySQL 5.6 Release Notes

Packaging Notes

• Packaging support was added for Ubuntu 15.10. (Bug #79104, Bug #22147191)

Security Notes

• yaSSL was upgraded to version 2.3.9. This upgrade corrects an issue in which yaSSL handled only

cases of zero or one leading zeros for the key agreement instead of potentially any number, which in

rare cases could cause connections to fail when using DHE cipher suites. (Bug #22361038)

• The linked OpenSSL library for the MySQL Commercial Server has been updated from version 1.0.1p

to version 1.0.1q. For a description of issues fixed in this version, see http://www.openssl.org/news/

vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #22348181)

Functionality Added or Changed

• InnoDB: A new InnoDB configuration option, innodb_tmpdir, allows you to configure a separate

directory for temporary files created during online ALTER TABLE operations that rebuild the table. This

option was introduced to help avoid MySQL temporary directory overflows that could occur as a result

of large temporary files created during online ALTER TABLE operations. innodb_tmpdir can be

configured dynamically using a SET statement.

Online ALTER TABLE operations that rebuild a table also create an intermediate table file in the same

directory as the original table. The innodb_tmpdir option is not applicable to intermediate table files.

(Bug #19183565)

• The Valgrind function signature in mysql-test/valgrind.supp was upgraded for Valgrind 3.11.

(Bug #22214867)

Bugs Fixed

• InnoDB: A small InnoDB buffer pool size with a large innodb_stats_persistent_sample_pages

setting resulted in a Difficult to find free blocks in the buffer pool warning. (Bug

#22385442)

• InnoDB: Starting the server with an empty innodb_data_home_dir entry in the configuration file

caused InnoDB to look for the buffer pool file in the root directory, resulting in a startup error. (Bug

#22016556, Bug #78831)

• InnoDB: A full-text query run under high concurrency caused a server exit due to an invalid memory

access. (Bug #21922532)

• InnoDB: With a large innodb_sort_buffer_size setting, adding an index on an empty table

performed more slowly than expected. (Bug #21762319, Bug #78262)

• Replication: When DML invokes a trigger or a stored function that inserts into an AUTO_INCREMENT

column, that DML has to be marked as an unsafe statement. If the tables are locked in the transaction

prior to the DML statement (for example by using LOCK TABLES), then the DML statement was not

being marked as an unsafe statement. The fix ensures that such DML statements are marked correctly

as unsafe. (Bug #17047208)

• Replication: As part of the fix for Bug #16290902, when writing a DROP TEMPORARY TABLE IF

EXISTS query into the binary log, the query is no longer preceded by a USE `db` statement. Instead

the query uses a fully qualified table name, for example DROP TEMPORARY TABLE IF EXISTS

MySQL 5.6 Release Notes

`db`.`t1`;. This changed the application of replicate-rewrite-db filter rules, as they work

only on the default database specified in a USE statement. This caused slaves to fail when the

resulting CREATE TEMPORARY TABLE was applied. The fix ensures that at the time of writing a DROP

TEMPORARY TABLE IF EXISTS query into the binary log, a check is made for the default database.

If it exists then the query is written as USE default_db in the binary log. If a default database is not

present then the query is logged with the qualified table name. (Bug #77417, Bug #21317739)

• Replication: If generating a GTID for a transaction fails, the transaction is not written

to the binary log but still gets committed. Although running out of GTIDs is a rare

situation, if it did occur an error was written to the binary log as a sync stage error. With

binlog_error_action=ABORT_SERVER, the server aborts on such an error, avoiding data

inconsistency. When binlog_error_action=IGNORE_ERROR, the server continues binary logging

after such an error, potentially leading to data inconsistency between the master and the slave. The fix

changes the error to be correctly logged as a flush stage error. (Bug #77393, Bug #21276561)

• Replication: When using --gtid-mode=ON , --enforce-gtid-consistency , and --

binlog-format=row, if a user defined function with multiple DROP TEMPORARY TABLE

statements was executed on a master, the resulting binary log caused an error on slaves.

The fix ensures that stored functions and triggers are also considered multi-statement

transactions, and that when --enforce-gtid-consistency is enabled, functions

with CREATE TEMPORARY TABLE or DROP TEMPORARY TABLE statements generate an

ER_GTID_UNSAFE_CREATE_DROP_TEMPORARY_TABLE_IN_TRANSACTION error. (Bug #77354, Bug

#21253415)

• Replication: Stored procedure local variables that were used in an ALTER EVENT statement were

not being replicated correctly. This was related to the fact that CALL statements are not written into

the binary log. Instead each statement executed in a stored procedure is binary logged separately,

with the exception that the statement string is modified so that uses of stored procedure local variables

are replaced with NAME_CONST('spvar_name', 'spvar-value') calls. DDL statements (which

are always binary logged in statement binary log mode irrespective of the current binary log format)

can also use stored procedure local variables and a clash could cause them to not be replicated

correctly. The fix ensures that any stored procedure local variables used in a statement are replaced with

NAME_CONST(...), except for the case when it is a DML statement and the binary log format is ROW.

(Bug #77288, Bug #21229951)

• Replication: DROP TABLE statements are regenerated by the server before being written to the binary

log. If a table or database name contained a non-regular character, such as non-latin characters, the

regenerated statement was using the wrong name, breaking replication. The fix ensures that in such a

case the regenerated name is correctly converted back to the original character set. Also during work on

this bug, it was discovered that in the rare case that a table or database name contained 64 characters,

the server was throwing an assert(M_TBLLEN < 128) assertion. The assertion has been corrected to

be less than or equal 128. (Bug #77249, Bug #21205695)

References: See also: Bug #78036, Bug #22261585, Bug #21619371.

• Replication: Irrespective of the current binlog_format setting, DDL that changes metadata on a

master is always identified and written to the binary log in STATEMENT format. Such DDL could occur

from event based SQL statements, such as CREATE EVENT or DROP EVENT, or transactions that had

unsafe functions such as sysdate(). When binlog_format=MIXED and attempting to replicate such

DDL, it was not being correctly identified and therefore was not being correctly replicated. (Bug #71859,

Bug #19286708)

• Microsoft Windows: Added Microsoft Visual Studio 2015 support. Changes include using the

native (added in VS 2015) timespec library if it exists, renamed lfind/lsearch and timezone/tzname

to avoid redefinition problems, set TMPDIR to "" by default as P_tmpdir no longer exists, deprecated

std::hash_map in favor of std::unordered_map, and added Wix Toolset 3.10 support. (Bug #21770366)

MySQL 5.6 Release Notes

References: See also: Bug #21657078.

• Inserting a token of 84 4-byte characters into a full-text index raised an assertion. The maximum token

length was 84 characters up to a maximum of 252 bytes, which did not account for 4-byte characters.

The maximum byte length is now 336 bytes. (Bug #22291765, Bug #79475)

• If a client attempted to use an unsupported client character set (ucs2, utf16, utf32), the error

message reported to the client differed for SSL and non-SSL connections. (Bug #22216715)

• Data corruption or a server exit could occur if a stored procedure had a variable declared as TEXT or

BLOB and data was copied to that variable using SELECT ... INTO syntax from a TEXT or BLOB column.

(Bug #22203532, Bug #22232332, Bug #21941152)

• CREATE TEMPORARY TABLE .. SELECT statements involving BIT columns that resulted in a column

type redefinition could cause a server exit or an improperly created table. (Bug #21902059)

• With character_set_server=utf16le, some values of ft_boolean_syntax could cause a server

exit for full-text searches. (Bug #21631855)

• With LOCK TABLES in force, an attempt to open a temporary MERGE table consisting of a view in its list

of tables (not the last table in the list) caused a server exit. (Bug #20691429)

• For certain prepared statements, the optimizer could transform join conditions such that it used a pointer

to a temporary table field that was no longer available after the initial execution. Subsequent executions

caused a server exit. (Bug #19941403)

• Repeated execution of ALTER TABLE v1 CHECK PARTITION as a prepared statement, where v1 is a

view, led to a server exit.

In addition, output for some administrative operations, when they are attempted on a view, changes

from “Corrupt” to “Operation failed”. These include ANALYZE TABLE, OPTIMIZE TABLE, and REPAIR

TABLE, and ALTER TABLE statements that perform ANALYZE PARTITION, CHECK PARTITION,

OPTIMIZE PARTITION, and REPAIR PARTITION operations. (Bug #19817021)

• Valgrind detected some possibly unsafe use of string functions in code used for asymmetric encryption.

(Bug #19688135)

• SSL connections ignored any change made by passing the MYSQL_OPT_READ_TIMEOUT option to the

mysql_options() C API function. (Bug #17618162)

• Solaris packages failed to note the dependency of the MySQL client library on the libstlport library.

(Bug #79778, Bug #22504264)

• Using systemd to start mysqld failed if configuration files contained multiple datadir lines. Now the

last datadir line is used. (Bug #79613, Bug #22361702)

• If server was started with --thread-handling=no-threads, no foreground thread was created for a

client connection. The Performance Schema did not account for the possibility of no foreground threads

for queries on the session_connect_attrs table, causing an assertion to be raised. (Bug #78292,

Bug #21765843)

• ALTER TABLE ... CONVERT TO CHARACTER SET operations that used the INPLACE algorithm were

ineffective if the table contained only numeric data types. Also, such operations failed to clean up their

temporary .frm file. (Bug #77554, Bug #21345391)

• Heavy SHOW PROCESSLIST or SELECT ... FROM INFORMATION_SCHEMA.PROCESSLIST activity

could result in the server accepting more than max_connections connections. (Bug #75155, Bug

#20201006)

MySQL 5.6 Release Notes

• When used with the libmysqld embedded server, the mysql_stmt_execute() C API function

failed with a malformed communication packet error, even for simple prepared statements. (Bug

#70664, Bug #17883203)

Changes in MySQL 5.6.28 (2015-12-07, General Availability)

• Functionality Added or Changed

• Bugs Fixed

Functionality Added or Changed

• MySQL Server RPM packages now contain a conflict indicator for MySQL Connector C, such that an

error occurs when installing MySQL Server if MySQL Connector C is also installed. To install MySQL

Server, remove any MySQL Connector C packages first. (Bug #21900800)

• These client programs now support the --enable-cleartext-plugin option: mysqlcheck,

mysqldump, mysqlimport, mysqlshow. This option enables the mysql_clear_password cleartext

authentication plugin. (See Client-Side Cleartext Pluggable Authentication.) (Bug #21235226)

• Support for building with Solaris Studio 5.13 was added. (Bug #21185883)

• mysql_upgrade now attempts to print more informative errors than FATAL ERROR: Upgrade

failed. (Bug #77803, Bug #21489398)

• Performance Schema digests in DIGEST_TEXT columns have ... appended to the end to indicate

when statements exceed the maximum statement size and were truncated. This is also now done for

statement text values in SQL_TEXT columns. (Bug #75861, Bug #20519832)

Bugs Fixed

• InnoDB: InnoDB returned an invalid corruption-related error message during an IMPORT TABLESPACE

operation. (Bug #21838158, Bug #77321)

• InnoDB: An old version of numactl headers on the build host caused a compilation error when building

a MySQL version that includes NUMA memory policy support. (Bug #21785074)

• InnoDB: An online ALTER TABLE operation caused a server exit. (Bug #21640679)

• InnoDB: A schema mismatch error occurred when importing a tablespace that was altered by DROP

INDEX operation on the source server. (Bug #21514135, Bug #77659)

• InnoDB: A duplicate key error that occurred during an online DDL operation reported an incorrect key

name. (Bug #21364096, Bug #77572)

• InnoDB: An ALTER TABLE operation caused the server to exit on disk full. (Bug #21326304, Bug

#77497)

• InnoDB: The system tablespace data file did not extend automatically when reaching the file size

limit, causing startup to fail with a size mismatch error and preventing the addition of another system

tablespace data file. (Bug #21287796, Bug #77128)

• InnoDB: Altering the lettercase of a column introduced an inconsistency between the .frm file and data

dictionary resulting in a failed CREATE INDEX operation on the altered column. (Bug #20755615)

• InnoDB: An ALTER TABLE operation that converted a table to an InnoDB file-per-table tablespace did

not check for unknown files with the same name as the destination .idb file, permitting an unknown file

of the same name to be overwritten. (Bug #19218794, Bug #73225)

MySQL 5.6 Release Notes

• Replication: As binlog_error_action=ABORT_SERVER is the default in MySQL 5.7.7 and later

it is being used for more error situations. The behavior has been adjusted to generate a core dump to

improve troubleshooting possibilities. (Bug #21486161, Bug #77738)

• Replication: On a multithreaded slave configured with master_info_repository=TABLE and

relay_log_info_repository=TABLE which had previously been run with autocommit=1,

if the slave was stopped and autocommit changed to 0, executing START SLAVE caused the

session to appear to hang. After the lock wait timeout, when START SLAVE proceeded the server

would stop unexpectedly. The fix ensures that when master_info_repository=TABLE,

relay_log_info_repository=TABLE, and autocommit=0 a new transaction is generated for start

and commit to avoid deadlocks. (Bug #21440793)

• Replication: Fatal errors encountered during flushing or synchronizing the binary log were being

ignored. Such errors are now caught and handled depending on the setting of binlog_error_action.

(Bug #76795, Bug #68953, Bug #20938915, Bug #16666407)

• Possible buffer overflow from incorrect use of strcpy() and sprintf() was corrected. (Bug

#21973610)

• MySQL RPM packages for RHEL5 failed to create the mysql system user. (Bug #21950975)

• For Debian package control files, libnuma-dev was added to Build-Depends to enable NUMA

support. (Bug #21822631)

• Selecting DECIMAL values into user-defined variables could cause a server exit. (Bug #21819304)

• Concurrent FLUSH PRIVILEGES and REVOKE or GRANT statements could produce a small time window

during which invalid memory access to proxy user information could occur, leading to a server exit. (Bug

#21602056)

• Starting the server with the query_alloc_block_size system variable set to certain negative values

on a machine without enough memory could result in out-of-memory errors. (Bug #21503595)

• Using UNINSTALL PLUGIN to uninstall the daemon_example plugin could cause a server exit. (Bug

#21467458)

• FLUSH DES_KEY_FILE failed to reload the DES key file. (Bug #21370329)

• If an error occurred during the setup phase of subquery materialization used to compute an IN predicate,

cleanup of the temporary table did not happen, leading to Valgrind errors. (Bug #21346081)

• Queries rejected by MySQL Enterprise Firewall were truncated to 512 characters when written to the

error log. (Bug #20948270)

• A server exit could occur for the second execution of a prepared statement for which an ORDER BY

clause referred to a column position. (Bug #20755389)

• Repeated execution of a prepared statement could cause a server exit if the default database was

changed. (Bug #20447262)

• Outer references do not work as arguments to MATCH(), but the server did not properly detect them.

Now it does and raises an error. (Bug #20007383)

References: See also: Bug #21140088.

• Valgrind errors were produced during row comparator setup. (Bug #19929406)

• After failure to create a temporary table during join processing and releasing the table descriptor, an

attempt to access the now-invalid descriptor could cause a server exit. (Bug #19918299)

MySQL 5.6 Release Notes

• Type conversion failure for DECIMAL values could cause a server exit. (Bug #19912326, Bug

#20013538)

• INSERT DELAYED could cause a server exit for tables partitioned with a character column as the key

and for which the expression required a character set conversion. (Bug #19894161)

• During a filesort for an UPDATE statement, the optimizer could access a stale pointer, resulting in a

server exit. (Bug #19893908)

• A server exit could occur when updating a view using an ALL comparison operator on a subquery that

selects from an indexed column in the main table. (Bug #19434916)

• Internal buffer sizes in resolve_stack_dump were increased to accommodate larger symbol space

requirements for C++ code. (Bug #78885, Bug #22071592)

• MySQL development RPM packages could fail to install if MySQL Connector/C development RPM

packages were installed. (Bug #78815, Bug #22005375)

• Some stress test files in the mysql-test/suite/innodb_stress directory had the executable file

mode set although they were not script files. (Bug #78403, Bug #21822413)

• The server initialization script used for the service mysql status command on Linux sometimes

incorrectly reported that the server was stopped. (Bug #77696, Bug #21768876)

Changes in MySQL 5.6.27 (2015-09-30, General Availability)

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

Security Notes

• yaSSL was upgraded to version 2.3.8.

Upgrading from older versions fixes a connection-failure issue when used with the thread pool plugin.

(Bug #20774956, Bug #21888925)

Functionality Added or Changed

• InnoDB: The new innodb_numa_interleave read-only configuration option allows you to

enable the NUMA interleave memory policy for allocation of the InnoDB buffer pool. When

innodb_numa_interleave is enabled, the NUMA memory policy is set to MPOL_INTERLEAVE for

the mysqld process. After the InnoDB buffer pool is allocated, the NUMA memory policy is set back to

MPOL_DEFAULT. This option is only available on NUMA-enabled Linux systems.

Thanks to Stewart Smith for the patch. (Bug #18871046, Bug #72811)

• RPM .spec files were updated so that MySQL Server builds from source RPM packages will include

the proper files to take advantage of operating system NUMA capabilities. This introduces a runtime

dependency on libnuma.so.1. RPM and yum detect this and refuse to install if that library is not

installed. (Bug #21775221)

Bugs Fixed

• InnoDB; Microsoft Windows: Setting lower_case_table_names=0 on a case-insensitive file system

could result in a hang condition when running an INSERT INTO ... SELECT ... FROM tbl_name

MySQL 5.6 Release Notes

operation with the wrong tbl_name lettercase. An error message is now printed and the server exits

when attempting to start the server with --lower_case_table_names=0 on a case-insensitive file

system. (Bug #20198490, Bug #75185)

• InnoDB: Reloading a table that was evicted while empty caused an AUTO_INCREMENT value to be

reset. (Bug #21454472, Bug #77743)

• InnoDB: Memory allocation sanity checks were added to the memcached code. (Bug #21288106)

• InnoDB: A memcached flush_all command raised an assertion. A function that starts a transaction

was called from within assertion code. (Bug #21239299, Bug #75199)

• InnoDB: A data corruption occurred on ARM64. GCC builtins did not issue the correct fences when

setting or unsetting the lock word. (Bug #21102971, Bug #76135)

• InnoDB: Server shutdown was delayed waiting for the purge thread to exit. To avoid this problem, the

number of calls to trx_purge() was reduced, and the trx_purge() batch size was reduced to 20.

(Bug #21040050)

• InnoDB: In READ COMMITTED mode, a REPLACE operation on a unique secondary index resulted in a

constraint violation. Thanks to Alexey Kopytov for the patch. (Bug #21025880, Bug #76927)

• InnoDB: The IBUF_BITMAP_FREE bit indicated that there was more free space in the leaf page than

was actually available. (Bug #20796566)

• InnoDB: The server failed to start with an innodb_force_recovery setting greater than 3. InnoDB

was set to read-only mode before redo logs were applied.

DROP TABLE is now supported with an innodb_force_recovery setting greater than 3. (Bug

#19779113)

• InnoDB: The trx_sys_read_pertable_file_format_id() function reported the wrong file format.

(Bug #19206671)

• Packaging; OS X: Using user=mysql during installation on OS X did not allow the mysql database

to be installed. To fix this problem, OS X packages now use the --no-defaults option when creating

this database. This also means that having a my.cnf file on the system no longer affects the installation.

(Bug #21364902)

• Partitioning: CREATE TABLE statements that used an invalid function in a subpartitioning expression

did not always fail gracefully as expected. (Bug #20310212)

• Partitioning: Error handling for failed partitioning-related ALTER TABLE operations against non-

partitioned tables was not performed correctly (Bug #20284744)

• Partitioning: ALTER TABLE when executed from a stored procedure did not always work correctly with

tables partitioned by RANGE. (Bug #77333, Bug #16613004, Bug #21246891)

• Replication: Repeatedly checking for ERR_LOCK_WAIT_TIMEOUT (as done, for example by repeatedly

executing SHOW SLAVE STATUS) during a prolonged write lock on a table led to an assert. (Bug

#21095969)

• Replication: If statement based logging was in use, when updating multiple tables in a single statement,

a single transaction could be logged as two different transactions. This was due to the binary logging

process not properly identifying statements which were operating over transactional tables. The fix

ensures that they are correctly identified, even if such statements do not change the contents of the

tables. (Bug #16621582, Bug #21349028)

MySQL 5.6 Release Notes

• Replication: When the dump thread was killed while dumping an inactive binary log, some events in this

log could be skipped and thus not replicated. (Bug #78337, Bug #21816399)

References: See also: Bug #74607, Bug #19975697.

• Replication: Under certain circumstances it was possible for Retrieved_Gtid_Set on the slave to

contain gaps while no gaps appeared in Executed_Gtid_Set or the slave's binary logs. This could

happen when slave rotated the relay log in such a way that the last event of this log contained the record

which set gtid_next, and was then restarted after reading GTIDs from the following log. Following the

restart, Retrieved_Gtid_Set contained GTIDs which were executed incorrectly as well as spurious or

"phantom" gaps.

TYhe fix for this problem adds a GTID to Retrieved_Gtid_Set before writing the event to the

relay log, rather than after. If for some reason writing to relay log fails, the GTID is removed from

Retrieved_Gtid_Set. (Bug #76959, Bug #21046372)

References: See also: Bug #17943188.

• Replication: SAVEPOINT and ROLLBACK TO SAVEPOINT within a trigger led to an assertion. (Bug

#76727, Bug #20901025)

• Replication: While a SHOW BINLOG EVENTS statement was executing, any parallel transaction was

blocked. The fix ensures that the SHOW BINLOG EVENTS process now only acquires a lock for the

duration of calculating the file's end position, therefore parallel transactions are not blocked for long

durations. (Bug #76618, Bug #20928790)

• Replication: If a CREATE VIEW statement failed, it was being incorrectly written to the binary log even

though it did not result in the creation of a partial view. The fix ensures that such statements are not

recorded in the binary log. Additionally it was found that when a statement which had failed on a master

was received by a slave with an expected error, if the statement was skipped on the slave, for example

due to a replication filter, the expected error was being compared with the actual error that happened

on the slave. The fix ensures that if a statement with an expected error is received by a slave, if the

statement has not been filtered, only then is it compared with the actual error that happened on the

slave. (Bug #76493, Bug #20797764)

• Replication: The action specified for binlog_error_action was not always honored correctly after a

hardware failure occurred during log rotation. (Bug #76379, Bug #20805298)

• Replication: Modifying the master_info_repository or relay_log_info_repository inside a

transaction and later rolling back that transaction left the repository in an unusable state. We fix this by

preventing any modification of these repositories inside a transaction. (Bug #74950, Bug #20074353)

• Replication: When relay_log_recovery is set, the error log entry that reports the new recovery

positions has been extended to also report the old relay log positions. (Bug #74089, Bug #21305976)

• Replication: When a master with --binlog_checksum=none and --gtid-mode=ON was

replicating to a slave with --binlog_checksum=crc32, restarting the slave's SQL thread caused

an Event crc check error. This was due to the Format_description_log_event from

the master not being correctly found in existing relay logs after restarting the slave's SQL thread.

The fix ensures that the Previous_gtids_log_event is correctly skipped and that the correct

Format_description_log_event is found in existing relay logs after restarting the slave's SQL

thread. (Bug #73806, Bug #20644100, Bug #76746, Bug #20909880)

• Replication: When using relay_log_info_repository=TABLE, the

mysql.slave_relay_log_info table is updated when a transaction is committed or when a flush

is performed explicitly, such as during relay log rotation. If a transaction that uses any nontransactional

tables (for example MyISAM tables) is split across multiple relay logs, it is partially committed on relay

MySQL 5.6 Release Notes

log flush. When gtid_mode=ON, this caused the same GTID to be used for the remaining portion of the

transaction, which raised an ER_GTID_NEXT_TYPE_UNDEFINED_GROUP error.

We fix this issue by postponing in such cases the update of the relay log information repository that

normally occurs on relay log rotation until the commit for the transaction in question has been executed.

This issue did not affect tables using transactional storage engines such as InnoDB. (Bug #68525, Bug

#16418100)

References: See also: Bug #21630907, Bug #76974.

• The CMake checks for NUMA availability could cause compilation problems on platforms without NUMA

support. (Bug #21774859)

• Certain subqueries as arguments to PROCEDURE ANALYSE() could cause a server exit. (Bug

#21350175)

• An assertion could be raised due to incorrect error handling if a SELECT ... FOR UPDATE subquery

resulted in deadlock and caused a rollback. (Bug #21096444)

• Selecting the result of an INSERT() function call to which input was passed as a hexidecimal string

could expose more information than was passed to the function. (Bug #21056907)

• The updatable property of a view is set during view creation. If the underlying table was dropped and re-

created as a nonupdatable one, the updatable property of the original view was not revised accordingly.

This could cause a server exit for attempts to insert or replace into the view is made. (This problem was

specific to views with multiple tables/views and did not occur with update statements.) (Bug #21039264)

• Servers linked against yaSSL and compiled with GCC 4.8.2 could fail to respond correctly to connection

attempts until several seconds after startup. (Bug #21025377)

• For tables with subpartitions, the server could exit due to incorrect error handling during partition pruning

if the partition could be identified but not the subpartition. (Bug #20909518)

• DELETE could check privileges for the wrong database when table aliases were used. (Bug #20777016)

• Within a trigger, use of a cursor that accessed OLD or NEW values from a row could cause a server exit.

(Bug #20760261)

• Long path name values for some options could lead to stack overflow. (Bug #20376760)

• MySQL sometimes produced no warning when it was unable to interpret a character in a given character

set. (Bug #20238729)

• On Windows, the validate_password plugin could cause a server exit during the dictionary check.

(Bug #18636874)

• On Windows, setting query_cache_min_res_unit to too large a value could result in a value of 0

and a subsequent server exit. (Bug #18487951)

• EXPLAIN of statements containing GROUP_CONCAT() could cause a server exit. (Bug #17865675)

• On Windows, heap corruption in the audit log plugin caused server startup failure. (Bug #14700102)

• RPM installation scripts failed if configuration files contained multiple datadir lines. Now the last

datadir line is used. (Bug #77878, Bug #21527467)

• For wait events, the Performance Schema uses the CYCLE timer by default, but failed to fall back to a

different timer if CYCLE was unavailable. (Bug #77577, Bug #21374104)

MySQL 5.6 Release Notes

• Updating VARCHAR and TEXT columns in the same UPDATE statement could produce incorrect results.

When a VARCHAR column was assigned to a TEXT column and the VARCHAR column was then set to a

different value, the TEXT column's result contained the VARCHAR column's new value. (Bug #77135, Bug

#21143080)

• If an INFORMATION_SCHEMA query that performed a table-open operation encountered a corrupt

table and attempted to repair it, a deadlock could occur, resulting in an aborted transaction without

an appropriate error being reported. Such queries now do not attempt table repair. (Bug #76912, Bug

#21021848)

• mysqladmin -u root -p could exit with a segmentation fault. (Bug #76538, Bug #20802751)

• mysqlimport --use-threads did not actually use multiple threads. (Bug #76480, Bug #20772273)

• The optimizer sometimes generates an index for a derived table (subquery in the FROM clause). If this

occurred for a statement executed within a stored program, a memory leak could occur. (Bug #76349,

Bug #20728894)

• For OS X 10.9 packages, the version_compile_os system variable indicated 10.8. (Bug #75581, Bug

#20400501)

• The optimizer could incorrectly assume an out-of-memory condition while optimizing a range scan for the

OR operator, resulting in overestimation of the number of qualifying rows. (Bug #75248, Bug #20229614)

• On platforms where the char is unsigned, the server was unable to parse collation definitions that

included non-7-bit ASCII characters. Affected platforms include ARM and PowerPC. Thanks to Alexey

Kopytov for the patch. (Bug #74891, Bug #20928289, Bug #21682439)

• The events_statements_history Performance Schema table could have an ERRORS column value

of 0 when other columns indicated there were errors. (Bug #74614, Bug #19929832)

• View creation from a UNION failed with a duplicate-column error if a SELECT statement in the UNION

other than the first used the same column name multiple times. (Bug #74539, Bug #19886430)

• Empty XML elements having the form <element/> were not handled correctly by the LOAD XML

statement. (Bug #67542, Bug #16171518)

Changes in MySQL 5.6.26 (2015-07-24, General Availability)

This release adds support for Debian 8 and Ubuntu 15.04.

• MySQL Enterprise Notes

• Performance Schema Notes

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

MySQL Enterprise Notes

• MySQL Enterprise Edition incorporates these changes for MySQL Enterprise Firewall:

• The firewall implements a DETECTING intrusion-detection mode. For accounts in this mode, the

firewall detects suspicious statements and writes them to the error log but does not deny access.

MySQL 5.6 Release Notes

The new Firewall_access_suspicious status variable counts the number of such statements.

The sp_set_firewall_mode() stored procedure now synchronizes between in-memory rules and

those in persistent storage for DETECTING mode, just as it does for PROTECTING mode.

• A new sp_reload_firewall_rules() stored procedure reloads the in-memory rules for a

registered account from the rules stored in the mysql.firewall_whitelist table, providing better

control over firewall operation for individual accounts.

• A new mysql_firewall_flush_status() function resets firewall access-counter status variables.

To upgrade MySQL Enterprise Firewall if you have a version installed from a previous release, first

uninstall the old version. Then install the new version and register your firewall configuration again. For

instructions, see Installing or Uninstalling MySQL Enterprise Firewall. (WL #8510)

Performance Schema Notes

• Current-event timing now provides more information. Previously, while a wait, stage, or statement

event was executing, the respective tables displayed the event with TIMER_START populated, but with

TIMER_END and TIMER_WAIT as NULL:

events_waits_current

events_stages_current

events_statements_current

To make it possible to determine how long a not-yet-completed event has been running, the timer

columns now are set as follows:

• TIMER_START is populated (unchanged from previous behavior)

• TIMER_END is populated with the current timer value

•

TIMER_WAIT is populated with the time elapsed so far (TIMER_END − TIMER_START)

To find events that have not yet completed (that is, have no END_EVENT_ID) and have taken longer

than N picoseconds thus far, monitoring applications can use this expression in queries:

WHERE END_EVENT_ID IS NULL AND TIMER_WAIT > N

(Bug #75156, Bug #20889406)

Security Notes

• Due to the LogJam issue (https://weakdh.org/), OpenSSL has changed the Diffie-Hellman key length

parameters for openssl-1.0.1n and up. OpenSSL has provided a detailed explanation at http://

openssl.org/news/secadv_20150611.txt. To adopt this change in MySQL, the following modifications

were made:

• The key length used in vio/viosslfactories.c for creating Diffie-Hellman keys has been

increased from 512 to 2,048 bits.

• The linked OpenSSL library for the MySQL Commercial Server has been updated from version 1.0.1m

to version 1.0.1p. Issues fixed in the new version are described at http://www.openssl.org/news/

vulnerabilities.html. This change does not affect the Oracle-produced MySQL Community build of

MySQL Server, which uses the yaSSL library instead.

(Bug #77275, Bug #21221862, Bug #18367167, Bug #21307471, Bug #21449838)

MySQL 5.6 Release Notes

Functionality Added or Changed

• Replication: When using a multithreaded slave, each worker thread has its own queue of transactions

to process. In previous MySQL versions, STOP SLAVE waited for all workers to process their entire

queue. This logic has been changed so that STOP SLAVE first finds the newest transaction that was

committed by any worker thread. Then, it waits for all workers to complete transactions older than that.

Newer transactions are not processed. The new logic allows STOP SLAVE to complete faster in case

some worker queues contain multiple transactions. (Bug #75525, Bug #20369401)

• Previously, the max_digest_length system variable controlled the maximum digest length for all

server functions that computed statement digests. However, whereas the Performance Schema may

need to maintain many digest values, other server functions such as MySQL Enterprise Firewall need

only one digest per session. Increasing the max_digest_length value has little impact on total

memory requirements for those functions, but can increase Performance Schema memory requirements

significantly. To enable configuring digest length separately for the Performance Schema, its digest

length is now controlled by the new performance_schema_max_digest_length system variable.

(Bug #20963147)

• Previously, changes to the validate_password plugin dictionary file (named by the

validate_password_dictionary_file system variable) while the server was running required a

restart for the server to recognize the changes. Now validate_password_dictionary_file can be

set at runtime and assigning a value causes the named file to be read without a restart.

In addition, two new status variables are available.

validate_password_dictionary_file_last_parsed indicates when the dictionary file was last

read, and validate_password_dictionary_file_words_count indicates how many words it

contains. (Bug #66697, Bug #14588145)

Bugs Fixed

• InnoDB: The ib_cursor_moveto function did not accept a search tuple with fewer fields than are

defined for the index. (Bug #21121197, Bug #77083)

• InnoDB: The ib_table_truncate function failed to release a transaction, resulting in a hang on

server shutdown. (Bug #21121164, Bug #77084)

• InnoDB: The ib_open_table_by_id function passed an incorrect argument to

dict_table_open_on_id. (Bug #21121084, Bug #77100)

• InnoDB: On Unix-like platforms, os_file_create_simple_no_error_handling_func and

os_file_create_func opened files in different modes when innodb_flush_method was set to

O_DIRECT. (Bug #21113036, Bug #76627)

• InnoDB: Opening a foreign key-referenced table with foreign_key_checks enabled resulted in an

error when the table or database name contained special characters. (Bug #21094069, Bug #77043)

• InnoDB: The page_zip_verify_checksum function returned false for a valid compressed page. (Bug

#21086723)

• InnoDB: An ALTER TABLE ... IMPORT TABLESPACE operation on a table with prefix index failed

with a schema mismatch error. (Bug #20977779, Bug #76877)

• InnoDB: A failure to load a change buffer bitmap page during a concurrent delete tablespace operation

caused a server exit. (Bug #20878735)

• InnoDB: An assertion was raised when InnoDB attempted to dereference a NULL foreign key object.

(Bug #20762798)

MySQL 5.6 Release Notes

• InnoDB: Importing a tablespace with a full-text index resulted in an assertion when attempting to rebuild

the index. (Bug #20637494)

• InnoDB: After dropping a full-text search index, the hidden FTS_DOC_ID and FTS_DOC_ID_INDEX

columns prevented online DDL operations. (Bug #20590013, Bug #76012)

• InnoDB: The InnoDB memcached plugin handled unsigned NOT NULL integer columns incorrectly.

Thanks to Piotr Jurkiewicz for the patch. (Bug #20535517, Bug #75864)

• InnoDB: A DROP DATABASE operation raised an assertion. (Bug #19929435)

• InnoDB: An index record was not found on rollback due to inconsistencies in the purge_node_t

structure. The inconsistency resulted in warnings and error messages such as “error in sec index entry

update”, “unable to purge a record”, and “tried to purge sec index entry not marked for deletion”. (Bug

#19138298, Bug #70214, Bug #21126772, Bug #21065746)

• Partitioning: In certain cases, ALTER TABLE ... REBUILD PARTITION was not handled correctly

when executed on a locked table. (Bug #75677, Bug #20437706)

• Replication: When using GTIDs, a multithreaded slave which had relay_log_recovery=1 and

that stopped unexpectedly could encounter a relay-log-recovery cannot be executed when

the slave was stopped with an error or killed in MTS mode error upon restart. The fix

ensures that the relay log recovery process checks if GTIDs are in use or not. If GTIDs are in use, the

multithreaded slave recovery process uses the GTID protocol to fill any unprocessed transactions. (Bug

#73397, Bug #19316063)

• Replication: When two slaves with the same server_uuid were configured to replicate from a single

master, the I/O thread of the slaves kept reconnecting and generating new relay log files without new

content. In such a situation, the master now generates an error which is sent to the slave. By receiving

this error from the master, the slave I/O thread does not try to reconnect, avoiding this problem. (Bug

#72581, Bug #18731252)

• Incorrect cost calculation for the semijoin Duplicate Weedout strategy could result in a server exit. (Bug

#21184091)

• MySQL Enterprise Firewall recorded prepared statements as they were received by the server, not as

normalized digests. (Bug #20929568)

• For MySQL Enterprise Firewall operation, max_digest_length had to be larger than

mysql_firewall_max_query_size or normalized statements were truncated. The

mysql_firewall_max_query_size has been removed so that issue no longer applies, but

max_digest_length should still be set large enough to avoid statement truncation. (Bug #20894024)

• Enabling MySQL Enterprise Firewall and binary logging could result in the server reading freed memory.

(Bug #20848324)

• For large values of max_digest_length, the Performance Schema could encounter an overflow error

when computing memory requirements, resulting in a server exit. (Bug #20738072)

• The Spencer regex library used for the REGEXP operator could be subject to heap overflow in some

circumstances. (Bug #20642505)

• A buffer-overflow error could occur for mysqlslap during option parsing. (Bug #20605441)

• An off-by-one error in string-copying code could result in a buffer overflow. (Bug #20359808)

• GROUP BY or ORDER BY on a CHAR(0) NOT NULL column could lead to a server exit. (Bug

#19660891)

MySQL 5.6 Release Notes

• For some status variables that should monotonically increase, SHOW GLOBAL STATUS in one session

could show them as decreasing when other concurrent sessions changed user or disconnected. (Bug

#18591145)

• An unnecessary memset() call invoked during Performance Schema digest operations has been

removed, which improves performance by reducing overhead. (Bug #77863, Bug #21528683)

• mysql-systemd-start failed if datadir was set in /etc/my.cnf. (Bug #77357, Bug #21262883)

• Compilation failed when building MySQL without the Performance Schema. (Bug #77292, Bug

#21229433)

• A call to the MySQL Enterprise Firewall sp_set_firewall_mode() stored procedure with an invalid

user name produced an error but added the user to the firewall_users table anyway. (Bug #76914,

Bug #21021875)

• Identifiers in normalized statements were sometimes quoted and sometimes not, an inconsistency

that caused matching failure for statement digests and digest texts. This caused problems for MySQL

Enterprise Firewall and for Performance Schema aggregation by digest. Identifiers now are quoted

consistently. (Bug #76723, Bug #20896539)

• Ubuntu packages were missing dependencies for killall and psmisc. (Bug #76716, Bug #20893836)

• On OS X 10.10 (Yosemite), mysqld failed to start automatically. The startup item has been replaced

with a launchd job, which enables the preference pane check box for automatic startup to work again.

(Bug #74434, Bug #19858350)

• When choosing join order, the optimizer could incorrectly calculate the cost of a table scan and choose a

table scan over a more efficient eq_ref join. (Bug #71584, Bug #18194196)

Changes in MySQL 5.6.25 (2015-05-29, General Availability)

• MySQL Enterprise Notes

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

MySQL Enterprise Notes

• Previously, enabling the mysql_firewall_trace system variable caused MySQL Enterprise Firewall

to write a file named firewall_trace.txt in the data directory. That is no longer done. Now with

mysql_firewall_trace enabled, for PROTECTING mode, the firewall writes rejected statements to

the error log.

Security Notes

• my_print_defaults now masks passwords. To display passwords in cleartext, use the new --show

option. (Bug #19953365, Bug #20903330)

Functionality Added or Changed

• MySQL Enterprise Firewall operates on parser states and does not work well together with the query

cache, which circumvents the parser. MySQL Enterprise Firewall now checks whether the query cache

is enabled. If so, it displays a message that the query cache must be disabled and does not load. (Bug

#20913616)

MySQL 5.6 Release Notes

• MySQL distributions now include an innodb_stress suite of test cases. Thanks to Mark Callaghan for

the contribution. (Bug #76347, Bug #20717127)

Bugs Fixed

• InnoDB; Partitioning: The CREATE_TIME column of the INFORMATION_SCHEMA.TABLES table now

shows the correct table creation time for partitioned InnoDB tables. The CREATE_TIME column of the

INFORMATION_SCHEMA.PARTITIONS table now shows the correct partition creation time for a partition

of partitioned InnoDB tables.

The UPDATE_TIME column of the INFORMATION_SCHEMA.TABLES table now shows when a partitioned

InnoDB table was last updated by an INSERT, DELETE, or UPDATE. The UPDATE_TIME column of the

INFORMATION_SCHEMA.PARTITIONS table now shows when a partition of a partitioned InnoDB table

was last updated. (Bug #69990, Bug #17299181)

• InnoDB: An assertion was raised on shutdown due to XA PREPARE transactions holding explicit locks.

(Bug #20816223, Bug #76567)

• InnoDB: The innodb_checksum_algorithm strict_* settings (strict_none, strict_innodb,

and strict_crc32) caused the server to halt when InnoDB encountered a valid but non-matching

checksum. For example, with innodb_checksum_algorithm=strict_crc32, a valid innodb

checksum would cause the server to halt. Now, instead of halting the server, InnoDB only prints an error

message. (Bug #20568464)

• InnoDB: The memcached set command permitted a negative expire time value. Expire time is stored

internally as an unsigned integer. A negative value would be converted to a large number and accepted.

The maximum expire time value is now restricted to INT_MAX32 to prevent negative expire time values.

(Bug #20478242, Bug #75790)

• InnoDB: Removal of a foreign key object from the data dictionary cache during error handling caused

the server to exit. (Bug #20442523)

• InnoDB: SHOW ENGINE INNODB STATUS output showed negative reservation and signal count values

due to a counter overflow error. (Bug #20417397)

• InnoDB: Failure to check the status of a cursor transaction read-only option before reusing the

cursor transaction for a write operation resulted in a server exit during a memcached workload. (Bug

#20391552)

• InnoDB: MDL locks taken by memcached clients caused a MySQL Enterprise Backup FLUSH TABLES

WITH READ LOCK operation to hang. (Bug #20275612)

• InnoDB: Estimates that were too low for the size of merge chunks in the result sorting algorithm caused

a server exit. (Bug #20049521)

• InnoDB: For full-text searches, the optimizer could choose an index that does not produce correct

relevancy rankings. (Bug #74686, Bug #19950568)

• Partitioning: When creating a partitioned table, partition-level DATA DIRECTORY or INDEX

DIRECTORY option values that contained an excessive number of characters were handled incorrectly.

(Bug #20809045)

• Partitioning: Executing an ALTER TABLE on a partitioned table on which a write lock was in effect

could cause subsequent SQL statements on this table to fail. (Bug #74288, Bug #74634, Bug

#19784790, Bug #19918805)

References: See also: Bug #19856162, Bug #74451.

MySQL 5.6 Release Notes

• Replication: Row unpacking did not function correctly in some cases when running the server with

binlog_row_image set to minimal. (Bug #20468712)

• Replication: When binary logging was enabled, using stored functions and triggers resulting in a long

running procedure that inserted many records caused the memory use to increase rapidly. This was due

to memory being allocated per variable. The fix ensures that in such a situation, memory is allocated

once and the same memory is reused. (Bug #75879, Bug #20531812)

• Replication: If an error was encountered while adding a GTID to the received GTID set, the log lock was

not being correctly released. This could cause a deadlock. (Bug #75781, Bug #20492319)

• Replication: A slave running MySQL 5.6.24 or earlier could not connect to a master running

MySQL 5.7.6 and later that had gtid_mode=OFF_PERMISSIVE or gtid_mode=ON_PERMISSIVE.

The fix ensures that a slave running MySQL 5.6.25 and later can connect to such a master as

long as the slave's gtid_mode is compatible. In other words, a slave running MySQL 5.6.25

and later which has gtid_mode=OFF can connect to a master running MySQL 5.7.6 and

later which has gtid_mode=OFF_PERMISSIVE, and a slave running MySQL 5.6.25 and later

which has gtid_mode=ON can connect to a master running MySQL 5.7.6 and later which has

gtid_mode=ON_PERMISSIVE. Other combinations are incompatible. (Bug #75769, Bug #20471216)

• Replication: If an error occurred when using a multithreaded slave, issuing a CHANGE MASTER

TO statement which resulted in an ER_MTS_CHANGE_MASTER_CANT_RUN_WITH_GAPS

error, and then issuing RESET SLAVE, made it impossible to change master due to repeated

ER_MTS_CHANGE_MASTER_CANT_RUN_WITH_GAPS errors. Running the debug version of mysqld

caused an unexpected exit in this case. The fix ensures that the recovery process for multithreaded

slaves avoids this. (Bug #75574, Bug #20411374)

• Replication: When using semisynchronous replication performance was degrading when the number

of threads increased beyond a certain threshold. To improve performance, now only the thread which is

committing is responsible for deleting the active transaction node. All other operations do not touch this

active transaction list. (Bug #75570, Bug #20574628)

• Replication: Using mysqlbinlog to process log events greater than 1.6GB failed with an out of

memory error. This was caused by an internal error converting the length variable. The fix upgrades

the length variable to avoid overflow in both encoding and decoding functions. (Bug #74734, Bug

#20350989)

• Replication: When master_info_repository=TABLE the receiver thread stores received event

information in a table. The memory used in the process of updating the table was not being freed

correctly and this could lead to an out of memory error. The fix ensures that after an event is flushed to

the relay log file by a receiver thread, the memory used is freed. (Bug #72885, Bug #19390463, Bug

#69848, Bug #20124342)

• Replication: Using mysqlbinlog to replay a relay log which ended with GTID_LOG_EVENT could

cause the following error:

ERROR 1790 (HY000) @@SESSION.GTID_NEXT cannot be changed by a client that

owns a GTID. The client owns UUID:GTID. Ownership is released on COMMIT or

ROLLBACK.

If a relay log rotate happens (either through a receiver thread restart or after issuing the ROTATE

command) exactly after writing a GTID_LOG_EVENT, when replaying such a relay log's end

ROTATE_EVENT, it was mistakenly identified as being inside a transaction, whereas the transaction

was actually started after GTID_LOG_EVENT. This caused mysqlbinlog to append SET

@@SESSION.GTID_NEXT='AUTOMATIC', resulting in two GTID_NEXT statements one after the other.

The fix ensures that mysqlbinlog generates SET @@SESSION.GTID_NEXT='AUTOMATIC' only

outside of a transaction and when there has not been a previous GTID_LOG_EVENT.

MySQL 5.6 Release Notes

Similarly, using mysqlbinlog to concatenate and replay a relay log which contained a partial

GTID transaction caused the above error. A relay log can contain a partial GTID transaction when

AUTO_POSITION is enabled if a receiver thread is restarted when it is in the middle of transferring a

transaction from a master. On restart the slave retrieves the full transaction again. In this case, the first

relay log contains a partial GTID transaction and the second relay log contains the full GTID transaction

again. When using mysqlbinlog to concatenate such a relay log, the partial transaction was not being

correctly detected and therefore a ROLLBACK was not being correctly generated. The fix identifies partial

GTID transactions using the format description event of the second relay log, ensuring that a ROLLBACK

is correctly added. (Bug #70711, Bug #17650326)

• For small values of the read_rnd_buffer_size system variable, internal caching of temporary results

could fail and cause query execution failure. (Bug #20895852)

• The normalize_statement() function used by MySQL Enterprise Firewall could cause a server exit

for certain password-related statements. (Bug #20873209)

• A failed FLUSH PRIVILEGES statement followed by statements to create or drop accounts could cause

a server exit. (Bug #20857652)

• MySQL Enterprise Firewall debug code could leak memory. (Bug #20849157)

• std::stringstream code used by MySQL Enterprise Firewall could cause a server exit. (Bug

#20848536)

• SHOW VARIABLES mutexes were being locked twice, resulting in a server exit. (Bug #20788853)

• ull2dec() was modified to avoid a problem with GCC 5 in optimized mode. (Bug #20768820)

• Using GCC 5, debug builds failed due to compiler warnings. (Bug #20768717)

• The mysql_firewall_max_query_size system variable should be read only at runtime, but it was

possible to modify it. (Bug #20608993)

• MySQL Enterprise Firewall could leak memory in the unlikely event of failure to store information in an

INFORMATION_SCHEMA table. (Bug #20593257)

• Under certain conditions, the libedit command-line library could write outside an array boundary and

cause a client program crash. (Bug #20318154)

• mysql_config_editor could exit abnormally while encrypting passwords. (Bug #20294225)

• Host value matching for the grant tables could fail to use the most specific of values that contained

wildcard characters. (Bug #20181776)

• For MySQL distributions linked against yaSSL, a corrupt client key file could cause clients to exit. (Bug

#20168526)

• For join queries with a large number of tables, the server could exit converting the join to a semijoin.

(Bug #20109861)

• Deleting rows from mysql.user following by granting privileges to a new account could result in a

server exit. (Bug #20031475)

• Renaming the mysql.procs_priv table and executing SHOW GRANTS resulted in a server exit. (Bug

#20006361)

• Within a stored procedure, access to view columns after DDL or FLUSH TABLES statements in the

procedure could cause a server exit. (Bug #19897405)

MySQL 5.6 Release Notes

• Execution of certain BINLOG statements while temporary tables were open by HANDLER statements

could cause a server exit. (Bug #19894987, Bug #20449914)

• For a prepared statement with an ORDER BY that refers by column number to a GROUP_CONCAT()

expression that has an outer reference, repeated statement execution could cause a server exit. (Bug

#19814337)

• CMake configuration was adjusted to handle new warnings reported by Clang 3.5, using the -

Wpointer-bool-conversion and -Wundefined-bool-conversion compiler options. (Bug

#19584183)

• Loading corrupt spatial data into a MyISAM table could cause the server to exit during index building.

(Bug #19573096)

• Specifying --general_log_file= (with an empty value) at server startup caused the server to fail

and exit. (Bug #19392264)

• CMake configuration was adjusted to handle warnings reported by Clang 3.3. (Bug #17486216)

• Some MySQL Enterprise Firewall diagnostic messages were written outside the control of the

log_error_verbosity system variable. (Bug #76612, Bug #20848331)

• The server rejected empty COM_SHUTDOWN packets. (Bug #76552, Bug #20810928)

References: This issue is a regression of: Bug #14525642.

• A Provides rule in RPM .spec files misspelled “mysql-embedded” as “mysql-emdedded”. (Bug

#76385, Bug #20734434)

• Inappropriate -Werror options could appear in mysql_config --cflags output. (Bug #76019, Bug

#20590904)

• Using a MySQL 5.6 version of mysqladmin to change the password for an account on a MySQL 5.7.6

installation resulted in an unusable account password. (Bug #76018, Bug #20590548)

• AddressSanitizer compilation errors were silenced. (Bug #75739, Bug #20459338, Bug #75740, Bug

#20459363)

• In the threads Performance Schema table, the PROCESSLIST_STATE and PROCESSLIST_INFO

values did not change for the thread/sql/main main thread instrument as the thread state changed.

(Bug #74517, Bug #19887143)

• Certain queries for the INFORMATION_SCHEMA TABLES and COLUMNS tables could lead to excessive

memory use when there were large numbers of empty InnoDB tables. (Bug #72322, Bug #18592390)

• Queries that included a HAVING clause based on nondeterministic functions could produce incorrect

results. (Bug #69638, Bug #17055185)

• For logging of prepared statements to the general query log, the Execute line was logged after

statement execution, not before. (Bug #69453, Bug #16953758, Bug #20536590)

• MySQL failed to compile using OpenSSL 0.9.8e. (Bug #68999, Bug #16861371)

Changes in MySQL 5.6.24 (2015-04-06, General Availability)

• Deprecation and Removal Notes

• MySQL Enterprise Notes

• Functionality Added or Changed

MySQL 5.6 Release Notes

• Bugs Fixed

Deprecation and Removal Notes

• ALTER TABLE did not take advantage of fast alterations that might otherwise apply to the operation to

be performed, if the table contained temporal columns found to be in pre-5.6.4 format (TIME, DATETIME,

and TIMESTAMP columns without support for fractional seconds precision). Instead, it upgraded the table

by rebuilding it. Two new system variables enable control over upgrading such columns and provide

information about them:

• avoid_temporal_upgrade controls whether ALTER TABLE implicitly upgrades temporal columns

found to be in pre-5.6.4 format. This variable is disabled by default. Enabling it causes ALTER TABLE

not to rebuild temporal columns and thereby be able to take advantage of possible fast alterations.

• show_old_temporals controls whether SHOW CREATE TABLE output includes comments to

flag temporal columns found to be in pre-5.6.4 format. Output for the COLUMN_TYPE column of the

INFORMATION_SCHEMA.COLUMNS table is affected similarly. This variable is disabled by default.

Both variables are deprecated and will be removed in a future MySQL version. (Bug #72997, Bug

#18985760)

MySQL Enterprise Notes

• MySQL Enterprise Edition now includes MySQL Enterprise Firewall, an application-level firewall that

enables database administrators to permit or deny SQL statement execution based on matching against

whitelists of accepted statement patterns. This helps harden MySQL Server against attacks such as

SQL injection or attempts to exploit applications by using them outside of their legitimate query workload

characteristics.

Each MySQL account registered with the firewall has its own statement whitelist, enabling protection to

be tailored per account. For a given account, the firewall can operate in recording or protecting mode,

for training in the accepted statement patterns or protection against unacceptable statements. For more

information, see MySQL Enterprise Firewall. (WL #7725)

Functionality Added or Changed

• CMake support was updated to handle CMake version 3.1. (Bug #20344207)

• The server now includes its version number when it writes the initial “starting” message to the error log,

to make it easier to tell which server instance error log output applies to. This value is the same as that

available from the version system variable. (Bug #74917, Bug #20052694)

• Statement digesting as done previously by the Performance Schema is now done at the SQL level

regardless of whether the Performance Schema is compiled in and is available to other aspects of server

operation that could benefit from it. The default space available for digesting is 1024 bytes, but can be

changed at server startup using the max_digest_length system variable. (WL #8354)

References: See also: Bug #18304086, Bug #20015246.

Bugs Fixed

• InnoDB: A TRUNCATE TABLE operation on a temporary table raised an assertion. The temporary table

object was incompletely constructed when reloaded from SYS_TABLES. (Bug #20527363, Bug #72080)

• InnoDB: A full-text phrase search returned an incorrect result. An empty string was handled incorrectly

when tokenizing a newly inserted row. (Bug #20465273, Bug #75755)

MySQL 5.6 Release Notes

• InnoDB: Optimizing a FULLTEXT index raised an assertion. The last optimized word of a FULLTEXT

index is stored in the CONFIG table value column which is defined as CHAR(50). An assertion was

raised when the last optimized word was greater than 50 characters in length. The CONFIG table value

column is defined as CHAR(200) as of MySQL 5.6.24 and MySQL 5.7.6.

If your innodb_ft_max_token_size setting is greater than 50, it is recommended that you recreate

existing InnoDB FULLTEXT indexes after upgrading to MySQL 5.6.24 or MySQL 5.7.6 to avoid this

issue. FULLTEXT indexes created after upgrading to MySQL 5.6.24 or MySQL 5.7.6 are unaffected.

(Bug #20418326)

• InnoDB: An InnoDB memcached extra_col_value[] array was freed without checking the allocated

flag, causing a server exit. (Bug #20400373)

• InnoDB: A DML operation performed while a flushing operation was in progress raised a memcached-

related assertion. (Bug #20390277)

• InnoDB: The memcached process_arithmetic_command raised an assertion. The wrong error code

was returned for a nonexistent decr key. (Bug #20386835)

• InnoDB: The expiration time (exptime) defined using the memcached set command was ignored.

InnoDB memcached set the expiration time to an interval value instead of a system time value. (Bug

#20381342, Bug #70055)

• InnoDB: An assertion was raised when the full-text search fts_savepoint_release() function

released a named transaction savepoint and all subsequent savepoints. Only the initial savepoint should

be released. (Bug #20341916)

• InnoDB: A full-text search optimization operation raised an assertion. (Bug #20281800)

• InnoDB: Due to a regression introduced in MySQL 5.6.20, mysqld stop did not stop the mysqld

server process while the InnoDB memcached plugin was active. (Bug #20078646, Bug #74956)

References: This issue is a regression of: Bug #18409840.

• InnoDB: An ALTER TABLE ... RENAME failure on a table with a FULLTEXT index raised an assertion.

(Bug #20043707)

• InnoDB: A severe error occurred during the log apply phase of an online ALTER TABLE operation

that was converting a table with a UTF-8 charset to ROW_FORMAT=REDUNDANT. (Bug #19843246, Bug

#19895661, Bug #20219871)

• InnoDB: When dummy tables are created, the autoinc_mutex member of the of the dict_table_t

object was created unnecessarily. Similarly, the zip_pad.mutex object of dict_index_t object was

created unnecessarily for dummy indexes. To avoid unnecessary mutex contention, autoinc_mutex

and zip_pad.mutex objects are now allocated and initialized on the first lock attempt. (Bug

#19788198, Bug #73361)

• InnoDB: An ALTER TABLE ... RENAME operation raised an invalid assertion. The assertion code

used an incorrect transaction object. (Bug #18523599)

References: This issue is a regression of: Bug #17447500.

• InnoDB: A memcached append operation on an INT column caused a segmentation fault. append

operations on INT columns are not supported and are now blocked. (Bug #75200, Bug #20209756)

• Partitioning: A number of ALTER TABLE statements that attempted to add partitions, columns, or

indexes to a partitioned table while a write lock was in effect for this table were not handled correctly.

(Bug #74451, Bug #74478, Bug #74491, Bug #74560, Bug #74746, Bug #74841, Bug #74860, Bug

MySQL 5.6 Release Notes

#74869, Bug #19856162, Bug #19864284, Bug #19873019, Bug #19891663, Bug #19990815, Bug

#20026661, Bug #20031966, Bug #20033503, Bug #19827845)

• Replication: When replicating from a MySQL 5.7.6 or later server to a MySQL 5.6.23 or earlier server,

if the older version applier thread encountered an Anonymous_gtid_log_event it caused an

assert. The fix ensures that these new log events added in MySQL 5.7.6 and later do not cause this

problem with MySQL 5.6.24 and later slaves. If gtid_mode is OFF and the applier thread encounters a

Gtid_log_event, the applier thread aborts with an error. If gtid_mode is ON and the applier thread

encounters a Anonymous_gtid_log_event, the applier thread aborts with an error. (Bug #20436436)

• Replication: When the automatic_sp_privileges variable is set, the server automatically

grants the EXECUTE and ALTER ROUTINE privileges to the creator of a stored routine, if the user

does not already have these privileges. When a privileged user creates a procedure with DEFINER

as a non privileged user on a master, the current user is considered to be a privileged user and the

mysql.procs_priv table is not updated. When such a statement was replicated to slave, the

non-privileged DEFINER was considered as the current user on the slave and privileges were being

allocated. This caused a difference in the privileges that were being allocated on the master and the

slave. The fix ensures that creater of the stored routine is added to the binary log, and the slave now

checks first if the user exists before granting privileges. To maintain compatibility with previous versions,

the DEFINER is used when the INVOKER is not available. As part of this fix, anonymous users can be

used to replicate from master to slave. (Bug #20049894)

• Replication: When using a slave configured to use a special character set such as UTF-16, UTF-32,

or UCS-2, the receiver (I/O) thread failed to connect. The fix ensures that in such a situation, if a slave's

character set is not supported then default to using the latin1 character set. (Bug #19855907)

• Replication: An internal problem with binary log group commit caused an incompatibility with the

threadpool plugin. (Bug #18845301)

• Replication: When gtid_mode=ON and slave_net_timeout was set to a low value, the slave I/O

thread could appear to hang. This was due to the slave heartbeat not being sent regularly enough when

the dump thread found many events that could be skipped. The fix ensures that the heartbeat is sent

correctly in such a situation. (Bug #74607, Bug #19975697)

• CMake failed to detect the OpenSSL version properly for recent versions of OpenSSL (the format of the

version string changed). (Bug #20756770)

• For execution of prepared statements, no check was made whether an audit log plugin returned an error,

so statement success could erroneously be returned. (Bug #20567900)

• Debian packages were missing some dependencies. (Bug #20561621)

• Following execution of a GRANT ... WITH GRANT OPTION statement, execution of a prepared

statement with a view could cause a server exit. (Bug #20030284)

• A user with a name of event_scheduler could view the Event Scheduler process list without the

PROCESS privilege. (Bug #20007583, Bug #20754369)

• Trying to create a user after dropping columns from the mysql.user table could result in a server exit.

(Bug #19910140)

• Ordering by a GROUP_CONCAT() result could cause a server exit. (Bug #19880368, Bug #20730220)

• A malformed mysql.proc table row could result in a server exit for DROP DATABASE of the database

associated with the proc row. (Bug #19875331)

• SHOW GRANTS after connecting using a proxy user could display the password hash of the proxied user.

(Bug #19817663)

MySQL 5.6 Release Notes

• Large values of the transaction_prealloc_size system variable could cause the server to allocate

excessive amounts of memory. The maximum value has been adjusted down to 128K. A similar change

was made for transaction_alloc_block_size. Transactions can still allocate more than 128K if

necessary; this change reduces the amount that can be preallocated, as well as the maximum size of the

incremental allocation blocks. (Bug #19770858, Bug #20730053)

• Certain queries on the INFORMATION_SCHEMA.INNODB_FT_CONFIG table could cause a server exit.

(Bug #19703520)

• A server exit could occur for queries that compared two rows using the <=> operator and the rows

belonged to different character sets. (Bug #19699237, Bug #20730155)

• Certain InnoDB errors caused stored function and trigger condition handlers to be ignored. (Bug

#19683834, Bug #20094067)

• The optimizer could raise an assertion due to incorrectly associating an incorrect field with a temporary

table. (Bug #19612819, Bug #20730129)

• Audit log filtering was not applied to connection events. (Bug #19509398)

• With audit_log_connection_policy=ERRORS, successful COM_QUIT events were errroneously

written to the audit log. With audit_log_statement_policy=NONE, no connection events were

written to the audit log, regardless of the current audit_log_connection_policy setting. (Bug

#19509373, Bug #21027210)

• The value of the Audit_log_events status variable did not equal the sum of the other audit log

counters. (Bug #19509336)

• The Audit_log_events_filtered status variable did not increment when audit log events were

filtered. (Bug #19509263)

• Many new features were added to the audit log plugin in MySQL 5.6.20, but the version number was not

increased. The version has been bumped to 1.1. (Bug #19502900)

• The server could exit due to an optimizer failure to allocate enough memory for resolving outer

references. (Bug #18782905, Bug #19892803)

• If the audit log file was found to be corrupt at server startup, an appropriate error message was not

always written. Also, if the plugin is loaded, it will be initialized regardless of whether the log was corrupt,

except in the case that renaming the log file fails. (Bug #14584292)

• Creating a FEDERATED table with an AUTO_INCREMENT column using a LIKE clause results in a server

exit. (Bug #12671631)

• Corrections were made for a number of code issues that resulted in compiler warnings about array

bounds, possibly uninitialized variables, and variables being set but not used. (Bug #75735, Bug

#20458574)

• NULL as an expression was not recognized as a literal for calculation of Performance Schema statement

digests. (Bug #74813, Bug #20015246)

• The group_concat_max_len system variable could be set to its maximum value at runtime, but not in

an option file. (Bug #74037, Bug #19670915)

• A server warning error message referred to the obsolete table_cache system variable rather than

to table_open_cache. Thanks to Daniël van Eeden for the patch to fix some of the instances. (Bug

#73373, Bug #19285052, Bug #75081, Bug #20135780)

MySQL 5.6 Release Notes

• In the DIGEST_TEXT column of Performance Schema statement events tables, references to system

variables of the form @@var_name were stored as @ @ var_name. (Bug #71634, Bug #18304086)

• If the WITH_SSL CMake option was specified with an incorrect path to the SSL installation or the path to

an unsupported (too old) SSL installation, the option was implicitly changed to the bundled value and

yaSSL was used instead. Now CMake exits with an error so the user knows that the option value must

be changed. (Bug #69744, Bug #17162055)

• mysql_real_connect() could close a file descriptor twice if the server was not running. (Bug #69423,

Bug #19226740)

• Notification of events for the general log were received by the audit log plugin only if the general query

log was enabled. Now notifications are posted regardless of whether the general query log is enabled.

(Bug #60782, Bug #12368204, Bug #20536590, Bug #75796, Bug #20479643)

Changes in MySQL 5.6.23 (2015-02-02, General Availability)

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

Security Notes

• The linked OpenSSL library for the MySQL Commercial Server has been updated from version 1.0.1j

to version 1.0.1k. Issues fixed in the new version are described at http://www.openssl.org/news/

vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #20375530)

• yaSSL was upgraded to version 2.3.7. (Bug #19695101, Bug #20201864)

Functionality Added or Changed

• SSL 2.0 and SSL 3.0 protocols are now explicitly disabled because they provide weak encryption. (Bug

#19820550)

References: See also: Bug #19921150.

• The valid date range of the SSL certificates in mysql-test/std_data has been extended to the year

2029. (Bug #18366947)

Bugs Fixed

• InnoDB: A tablespace export operation set the purge state to PURGE_STATE_STOP, but the purge

thread did not check the purge state until the current purge operation was completed. In the case of a

large history list, the tablespace export operation was delayed, waiting for the current purge operation to

finish. The purge state is now checked with every purge batch. (Bug #20266847, Bug #75298)

• InnoDB: An ALTER TABLE ... ADD INDEX operation raised an assertion due to assertion code that

did not allow an online index status of ONLINE_INDEX_ABORTED_DROPPED. The assertion code was

relaxed. (Bug #20198726)

• InnoDB: An error occurred when the push_warning_printf function was invoked during

server recovery. This function was previously used to print a warning message to the client. Also,

current_thd was NULL when the server was restarted. (Bug #20144839)

MySQL 5.6 Release Notes

• InnoDB: The INNODB_METRICS adaptive_hash_searches_btree counter failed to report counter

data. (Bug #20080942, Bug #74511)

• InnoDB: An ALTER TABLE operation that changed the name of a foreign key column resulted in a

failure when reloading the foreign key constraint. The previous column name remained in the data

dictionary cache instead of being evicted. (Bug #20031243)

• InnoDB: With foreign_key_checks disabled, an assertion was raised when adding a foreign key

constraint on a renamed column that was part of a previous foreign key constraint. (Bug #20029625)

• InnoDB: Error messages regarding a size limitation on BLOB or TEXT data inserted in a single

transaction were revised. (Bug #19975322)

• InnoDB: DML operations on a table with full-text search indexes raised an invalid assertion. (Bug

#19905246)

References: This issue is a regression of: Bug #19314480.

• InnoDB: A multiple-table delete operation caused the server to halt. (Bug #19815702)

• InnoDB: A FLUSH TABLES operation raised an assertion. (Bug #19803418)

• InnoDB: With change buffering enabled, a buffered sequence of operations that should not have been

buffered resulted in an Unable to purge a record error. (Bug #19528825, Bug #73767)

• InnoDB: On non-Windows platforms, os-file_pread and os_file_pwrite functions return -1 when

an error occurs. This value was printed in an error message as the number of bytes read or written.

Instead of printing the -1 value in the error message, a separate error message indicating a system call

failure is now printed. Thanks to David Bennett for the patch. (Bug #19315210, Bug #73365)

• InnoDB: A slow shutdown (innodb_fast_shutdown=0) after crash recovery raised an assertion. Slow

shutdown did not wait for background rollback operations to finish before proceeding. (Bug #16862810)

• InnoDB: The integer column value was handled incorrectly for the memcached incr and decr

commands. (Bug #69415, Bug #20083106, Bug #74874, Bug #20044123)

• Partitioning: A failed ALTER TABLE ... TRUNCATE PARTITION statement or a failed TRUNCATE

TABLE statement against a partitioned table sometimes left inconsistent metadata in the table cache;

subsequent SQL statements reusing this metadata failed, and could in some cases also lead to a failure

of the server. (Bug #74292, Bug #19786861)

• Replication: If a client thread on a slave executed FLUSH TABLES WITH READ LOCK while the

master executed a DML, executing SHOW SLAVE STATUS in the same client became blocked, causing

a deadlock. The fix ensures that the read lock is only held during the period that the relay log is being

updated and the deadlock is avoided. (Bug #19843808)

• Replication: Ignorable log events were introduced in MySQL 5.6, but were found to not be functioning

correctly. This has now been fixed. (Bug #74683, Bug #19949915)

• Replication: When an XA transaction was active, executing an internal rollback, for example using

the BINLOG statement, resulted in an assertion. The fix ensures that a rollback happens only for

a slave when a transaction spans multiple binary log files. Rollback does not happen now if the

Format_description comes from the BINLOG statement being executed in the MySQL client. (Bug

#74597, Bug #19928622)

• Replication: In normal usage, it is not possible for a slave to have more GTIDs than the master. But in

certain situations, such as after a hardware failure or incorrectly cleared gtid_purged, the master's

binary log could be truncated. This fix ensures that in such a situation, the master now detects that the

MySQL 5.6 Release Notes

slave has transactions with GTIDs which are not on the master. An error is now generated on the slave

and the I/O thread is stopped with an error. The master's dump thread is also stopped. This prevents

data inconsistencies during replication. (Bug #72635, Bug #18789758)

• Replication: When using SHOW SLAVE STATUS to monitor replication performance,

Seconds_Behind_Master sometimes displayed unexpected lag behind the master. This was

caused by Previous_gtids log events being written to the slave's relay log with a timestamp behind

the master, and then being used to calculate the Seconds_Behind_Master. This fix ensures that

events generated on the slave that are added to the relay log and are not used when calculating

Seconds_Behind_Master. (Bug #72376, Bug #18622657)

• On Ubuntu 14.10, MySQL install operations could fail to reload AppArmor. (Bug #20092641)

• EXPLAIN within an XA transaction could raise an assertion. (Bug #19941492)

• Unlocking a temporary table after locking and truncating it could cause a server exit. (Bug #19786309)

• The Enterprise Encryption plugin could mishandle string arguments. (Bug #19688008, Bug #20730103)

• Binary log files created by streaming the binary log from a remote server with mysqlbinlog were given

an access mode more permissive than the original files. (Bug #19649868)

• If the audit_log plugin encountered a disk-full error, the server would exit.

Now, if the file system to which the audit log is being written fills up, a “disk full” error is written to the

error log. Audit logging continues until the audit log buffer is full. If free disk space has not been made

available by the time the buffer fills, client sessions will hang, and stopping the server at the time of client

sessions hanging will result in audit log corruption. To avoid this if client sessions are hung, ensure that

free space is available on the audit logging file system before stopping the server. (Bug #19411485)

• For failure to create a temporary table due to being out of file descriptors, the server exited rather than

returning an error. (Bug #18948649)

• For some queries that contained a derived table (subquery in the FROM clause), delay of materialization

resulted in a suboptimal execution plan due to a less accurate row-count estimate. (Bug #18607971)

• For UPDATE and DELETE statements, the server could exit after attempting to access an uninitialized

data structure. (Bug #18036143)

• Starting the server with start service or mysqld_safe could result in failure to use the correct

plugin directory. (Bug #17619241)

• FLUSH TABLES on a FEDERATED table failed if the table had been idle longer than the wait_timeout

time plus the TCP keepalive time. (Bug #17599258)

• Selecting all columns from INFORMATION_SCHEMA.TABLES did not reopen tables if they were in the

table cache, but selecting a subset of those columns under the same conditions did reopen tables. (Bug

#16869534)

• If my_write() encountered a disk-full condition, it could return an incorrect error value. (Bug

#16078792, Bug #19984788)

• A malformed data packet could cause the server to exit. (Bug #10063897)

• InnoDB boolean full-text searches incorrectly handled + combined with parentheses; for example,

+word1 +(>word2 <word3). (Bug #74845, Bug #20028323)

• MySQL failed to compile with GCC 4.9.1 in debug mode. (Bug #74710, Bug #19974500)

MySQL 5.6 Release Notes

• For debug builds, the server could exit due to an optimizer failure to allocate enough memory for group

references. (Bug #74447, Bug #19855522)

• The server no longer logs the following warnings because they are uninformative: Client failed to provide

its character set. 'charset' will be used as client character set. (Bug #72543, Bug #18708334)

• A file created for an internal temporary table could cause problems if the file was orphaned for some

reason and the file name was reused for later queries. (Bug #32917, Bug #11747548)

Changes in MySQL 5.6.22 (2014-12-01, General Availability)

• Compilation Notes

• Deprecation and Removal Notes

• Security Notes

• Bugs Fixed

Compilation Notes

• Noisy compiler warnings on FreeBSD 10 were silenced. (Bug #18790490)

• CMake workarounds for older OS X and XCode versions were removed. On OS X, compilation always

uses Clang, even for 32-bit builds.

Compilation on OS X is now supported for OS X 10.8 and up, using XCode 5 and up. Compilation on

older versions may work but is unsupported. (Bug #18510941)

• Previously, the MYSQL_MAINTAINER_MODE CMake option was turned on by default for debug builds

and off for release builds, and MYSQL_MAINTAINER_MODE caused -Werror to be enabled when

building with GCC. This made it cumbersome to enable -Werror under certain conditions, such as

when compiling with Clang.

Now, MYSQL_MAINTAINER_MODE is on by default when compiling debug builds with GCC, and

MYSQL_MAINTAINER_MODE enbles -Werror regardless of whether GCC or Clang is used. Enabling

-Werror with Clang can be done simply by explicitly setting -DMYSQL_MAINTAINER_MODE=1 when

running CMake. In addition, some compilation warnings reported by Clang 3.4 were fixed, making it

possible to build the default debug build with -Werror. (Bug #18313717)

• Build support was modified to produce the same warnings for Clang as for gcc. (Bug #17959689)

• CMake configuration for the Clang compiler sets more appropriate flags for building on Linux.

Specifically, -g -fno-omit-frame-pointer -fno-strict-aliasing is now added. (Bug

#17633291)

Deprecation and Removal Notes

• Replication: The variable binlogging_impossible_mode now has an alias named

binlog_error_action, which is the preferred name. binlogging_impossible_mode is now

deprecated. (Bug #19507567)

• Replication: The global scope for the sql_log_bin system variable has been deprecated, and this

variable can now be set with session scope only. The statement SET GLOBAL SQL_LOG_BIN now

produces an error. It remains possible to read the global value of sql_log_bin, but doing so produces

a warning. You should act now to remove from your applications any dependencies on reading this

value; the global scope sql_log_bin is removed in MySQL 8.0. (Bug #67433, Bug #15868071)

MySQL 5.6 Release Notes

• OLD_PASSWORD() is deprecated, but no warning was produced when it was invoked. (Bug #73376, Bug

#19285177)

Security Notes

• yaSSL was upgraded to version 2.3.5. (Bug #19695101, Bug #20201864)

• The linked OpenSSL library for the MySQL Commercial Server has been updated from version 1.0.1h

to version 1.0.1j. Issues fixed in the new version are described at http://www.openssl.org/news/

vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #74174, Bug #19717832)

Bugs Fixed

• InnoDB: An ALTER TABLE operation raised an assertion. When a foreign key object was removed from

the dictionary cache, an incorrect foreign key object was removed from the rb-tree. (Bug #19908343)

References: This issue is a regression of: Bug #18806829.

• InnoDB: In debug builds, setting the innodb_limit_optimistic_insert_debug debug

configuration option to 1 caused an infinite B-tree page split. (Bug #19904003, Bug #74605)

• InnoDB: The dict_set_corrupted() function attempted to update the clustered index of the

SYS_INDEXES data dictionary table incorrectly. (Bug #19584379)

• InnoDB: Pages with a checksum value of zero were incorrectly treated as empty pages. A page should

only be considered empty if its checksum value and LSN field values are zero. (Bug #19500258, Bug

#73689)

References: This issue is a regression of: Bug #17335427.

• InnoDB: The InnoDB data dictionary was not updated when a ALTER TABLE ... CHANGE COLUMN

operation changed the case of the column name. (Bug #19465984)

• InnoDB: A memory access violation caused fts_optimize_thread and mysqld to terminate. (Bug

#19314480)

• InnoDB: A procedure, called from a function to perform an operation on a temporary table, caused the

server to halt. (Bug #19306524)

• InnoDB: Attempting to shut down the server after starting the server with innodb_force_recovery=6

resulted in a hang. (Bug #19265668, Bug #73341)

• InnoDB: A COMMIT operation related to full-text search resulted in a segmentation fault. (Bug

#18503734)

• InnoDB: If a database is named using uppercase letters on a MySQL server with

lower_case_table_names=2 (which is default on OS X), InnoDB stores the database name as

specified in the InnoDB internal system table (SYS_TABLES) but stores the name in lowercase on disk.

During crash recovery, the case mismatch resulted in a conflict that marked the tablespace .ibd file

as missing. The patch for this bug converts database names to lowercase on crash recovery. (Bug

#18412598, Bug #72043)

• InnoDB: In debug builds, the InnoDB Lock Monitor asserted after a DROP TABLE operation, and the

InnoDB Monitor encountered an assertion in buf_page_get_gen. (Bug #18062698, Bug #71343, Bug

#18173184, Bug #68116)

MySQL 5.6 Release Notes

• InnoDB: A CREATE TABLE operation that failed when innodb_strict_mode was enabled succeeded

without printing a warning when innodb_strict_mode was disabled. (Bug #17852083)

• InnoDB: For explicit cache coherency, a write barrier was added to the head of

os_thread_create_func(), and a read barrier was added to assertion code in

rw_lock_free_func(). (Bug #13364876, Bug #62692, Bug #18870970, Bug #72809)

• InnoDB: The MySQL 5.6.20 patch for Bug #16963396 / MySQL Bug #69477 limited the size

of redo log BLOB writes to 10% of the redo log file size. This limitation has been relaxed. Redo

log BLOB writes are now limited to 10% of the total redo log size (innodb_log_file_size *

innodb_log_files_in_group).

As a result, innodb_log_file_size * innodb_log_files_in_group should be 10 times larger

than the largest BLOB data size found in the rows of your tables plus the length of other variable length

fields (VARCHAR, VARBINARY, and TEXT type fields). No action is required if innodb_log_file_size

* innodb_log_files_in_group is already sufficiently large or if your tables contain no BLOB data.

(Bug #73707, Bug #19498877)

References: See also: Bug #16963396.

• Partitioning: When multiple columns are used in KEY partitioning, their order may help determine

the partition in which the row is placed. Changing this order by means of an ALTER TABLE that uses

ALGORITHM=INPLACE can lead to inconsistency when placing rows in partitions; in other words, a row

inserted before such an operation is placed in one partition, but the same row inserted afterwards is

placed in a different one. For this reason, altering the order of a multicolumn index online is no longer

allowed when that index is also used as the base for partitioning the table by KEY; instead, you must use

a copying ALTER TABLE to perform the change. (Bug #17896265)

• Replication: When using a MySQL version that had been compiled with the WITH_DEBUG option

enabled, using expire_logs_days to purge binary logs caused a restart to crash the server. This

problem arose after the fix for Bug #17283409. The fix ensures that current_thd is checked before

calling DEBUG_SYNC(). (Bug #19553099)

• Replication: Sometimes the slave I/O thread leaves a partial group in the current relay log, for

example when it is killed or stopped. After it is restarted, a new relay log is created on rotation

and a pair of ROTATE_EVENT and FORMAT_DESCRIPTION_EVENT is replicated from master and

written into the new relay log. When using a multithreaded slave, problems such as error 1755 were

encountered when applying the remaining part of the group in the relay log. This fix ensures that if

MASTER_AUTO_POSITION is enabled, then the worker rolls back the partial group, finishes its work, and

then applies the new complete copy of the group. If MASTER_AUTO_POSITION is disabled, the worker

does not roll back the partial group. (Bug #19545298)

• Replication: A corrupted header length in FORMAT_DESCRIPTION_LOG_EVENT could cause the server

to stop unexpectedly. This was due to FORMAT_DESCRIPTION_LOG_EVENT being considered invalid if

the header length was too short. (Bug #19145712)

• Replication: Start log events were not checked by slaves for minimum size. (Bug #19145698)

• Replication: When using row-based replication with slave_type_conversions enabled, a binary

log with more than one Rows_log_event in succession caused a crash. This was due to the temporary

tables generated as part of the slave_type_conversions process being released too early. This fix

ensures that the temporary tables are not released too early, and also ensures that long transactions do

not cause an out of memory error. (Bug #18770469, Bug #19704825)

• Replication: When using binary log files that had been manually copied from the master, for

example to avoid I/O thread reading delay, a multithreaded slave generated error 1755. Because

the Previous_gtids log event is logged using the master's server_id and not the slave's

MySQL 5.6 Release Notes

server_id, the previous events were not being skipped correctly. This fix ensures that the events

in Previous_gtids log event are always skipped, regardless of whether they are from the relay log

(generated on the slave) or from the binary log (generated on the master and manually copied to the

slave as the relay log). (Bug #17812024)

• Replication: When replicating from an earlier version MySQL master, such as version 4.1, checksums

are not used for events. Replicating to a slave running a newer version of MySQL, such as version 5.6,

which has slave_sql_verify_checksum enabled by default meant that the last 4 bytes of events

from the older master were being incorrectly interpreted as the checksum. A warning is now generated

and to avoid such a situation, set slave_sql_verify_checksum=0 to disable checksums on the

slave. (Bug #17276183)

• Replication: When restarting MySQL with relay_log_recovery enabled to recover from a crash,

if the SQL thread had never been started, the position from which to start recovery was not correctly

initialized because Relay_Master_Log_File was missing. This fix ensures that in such a situation

each of the relay logs, starting from the first relay log file, is searched for a rotate event from the master,

which specifies where replication started from. This rotate event is then used to set the SQL thread's

Relay_Master_Log_File and Relay_Log_Pos and recovery continues as normal. (Bug #73039,

Bug #19021091)

• Replication: When using GTIDs for replication and with MASTER_AUTO_POSITION enabled, if a

slave requested GTIDs which had been already been purged by the master, the master was sending

all available GTIDs. This happened because the master reads all available binary logs and searches

for a binary log which contains a GTID that is not contained in the union of gtid_executed and

gtid_retrieved. If such a GTID is found, the master starts sending the information starting from that

location. In a situation where the union of the slave's gtid_executed and gtid_retreived set did

not contain the master's gtid_purged set, the slave would expect GTIDs which had already been

purged by the master. This fix ensures that in such a situation, the slave's I/O thread is aborted with

an error "Master has purged binary logs containing GTIDs that the slave requires.". (Bug #73032, Bug

#19012085)

• Replication: A kernel mutex contention was being caused because mysqlbinlog was calling

localtime() for every event read, which in turn called stat(/etc/localtime). This fix ensures that

mysqlbinlog uses localtime_r(), which is optimized to store the read only timezone internal structure.

This also means that mysqlbinlog now establishes the time zone at the beginning of processing and

you can not change it during processing. This is the same behavior as MySQL server. (Bug #72701, Bug

#18808072)

• Microsoft Windows: On Windows, the replace utility did not work. (Bug #16581605)

• The AppArmor profile installed by Debian packages was missing entries required for successful server

startup. (Bug #20057782)

• InnoDB table checksum calculation could yield an incorrect result if the value of the

innodb_checksum_algorithm system variable was modified during the operation. (Bug #19931177)

• For a materialized internal temporary table used with semijoins, the optimizer could add an index to it but

then use an inappropriate lookup strategy, causing a server exit. (Bug #19695490, Bug #21782943)

• GROUP BY or ORDER BY on a CHAR(0) NOT NULL column could lead to a server exit. (Bug

#19660891)

• With the validate_password plugin activated and dictionary lookups enabled, passing a user-defined

variable to PASSWORD() could cause a server exit. (Bug #19388163)

• Debian packages were built using the complex set of character sets, not the all set of character sets.

(Bug #19363801)

MySQL 5.6 Release Notes

• mysqldump failed to report a disk-full error if the dump destination was located on an NFS mount. (Bug

#18817867)

• Previously, InnoDB permitted a foreign key to be created which referenced a parent table for which

the user did not have sufficient privileges. Now, the user must have at least one of the SELECT,

INSERT, UPDATE, DELETE, or REFERENCES privileges for the parent table to create a foreign key. (Bug

#18790730, Bug #11746917)

• Copying InnoDB tables containing full-text columns from Windows to Linux caused a server exit on

Linux during full-text index initialization. (Bug #18285007, Bug #19864963, Bug #73155)

• On Debian, apt-get upgrade did not replace some packages from the repository. The workaround is

to first manually install mysql-client by running apt-get install mysql-client or directly run

apt-get dist-upgrade. (Bug #75485, Bug #20348793)

• On CentOS 6, specifying a relative path name for the --socket option caused MySQL startup script

failure. (Bug #74111, Bug #19775856)

• In Solaris 11.2, dtrace -V output changed from Sun D to Oracle D, causing detection of DTrace

availability to fail during MySQL configuration. (Bug #73826, Bug #19586917)

• mysql_config --libs_r produces output containing link flags for libmysqlclient_r, even

though that library was removed in MySQL 5.5 and replaced with a symbolic link to the underlying

libmysqlclient library. The output now refers directly to libmysqlclient. (The implication is that

it is no longer necessary to maintain the symbolic link for the sake of being able to use mysql_config

--libs_r.) (Bug #73724, Bug #19506315)

• For statement digest calculation, the Performance Schema failed to recognize signed literal numbers as

values representable by ? and created multiple digests for statements that should have had the same

signature. Now all instances of unary plus and unary minus followed by a number reduce to ? in digests.

(Bug #73504, Bug #19389709)

• Compilation on Windows using Visual Studio 2013 resulted in “unresolved external symbol” errors. (Bug

#73461, Bug #19351573)

• Certain queries for which subquery materialization or UNION DISTINCT was used together with a hash

index on a temporary table could produce incorrect results or cause a server exit. (Bug #73368, Bug

#19297190)

• The IS_FREE_LOCK() and IS_USED_LOCK() function implementations contained a race condition

due to which they could access freed memory when a user lock was concurrently checked and freed.

Accessing freed memory could result in an incorrect function return value or server exit. (Bug #73123,

Bug #19070633)

• LOCK TABLES sometimes acquired an insufficiently strong lock for implicitly locked tables. (Bug #72887,

Bug #18913551)

• The ENABLED_LOCAL_INFILE CMake option incorrectly was enabled by default. (Bug #72106, Bug

#18448743)

• Use of ODBC-format date literals could produce incorrect query results. (Bug #69233, Bug #16812821)

• mysql_install_db ignored option files in the default locations. (Bug #68807, Bug #16570238)

• mysql_setpermission failed to properly quote user names in SQL statements that it generated. (Bug

#66317, Bug #14486004)

Changes in MySQL 5.6.21 (2014-09-23, General Availability)

MySQL 5.6 Release Notes

• Deprecation and Removal Notes

• MySQL Enterprise Notes

• Functionality Added or Changed

• Bugs Fixed

Deprecation and Removal Notes

• The thread_concurrency system variable is deprecated, but no warning resulted from setting it at

server startup. (Bug #17873011)

• The --skip-innodb option is now deprecated and its use results in a warning. It will be removed in a

future MySQL version. This also applies to its synonyms (--innodb=OFF, --disable-innodb, and so

forth). (WL #7976)

MySQL Enterprise Notes

• MySQL Enterprise Edition now includes a set of encryption functions based on the OpenSSL library

that expose OpenSSL capabilities at the SQL level. These functions enable Enterprise applications to

perform the following operations:

• Implement added data protection using public-key asymmetric cryptography

• Create public and private keys and digital signatures

• Perform asymmetric encryption and decryption

• Use cryptographic hashing for digital signing and data verification and validation

For more information, see MySQL Enterprise Encryption. (WL #7717)

Functionality Added or Changed

• Replication: The new variable simplified_binlog_gtid_recovery can be used to change the

way binary log files are searched for previous GTIDs during recovery, speeding up the process when a

large number of binary log files exist. (Bug #69097, Bug #16741603, Bug #74071, Bug #19686914)

• Internally, spatial data types such as Geometry are represented as BLOB values, so when invoked with

the --hex-blob option, mysqldump now displays spatial values in hex. (Bug #43544, Bug #11752369)

Bugs Fixed

• InnoDB; Partitioning: Large numbers of partitioned InnoDB tables could consume much more memory

when used in MySQL 5.6 or 5.7 than the memory used by the same tables used in previous releases of

the MySQL Server. (Bug #17780517, Bug #70641)

References: This issue is a regression of: Bug #11764622, Bug #57480.

• InnoDB: An ALTER TABLE ... ADD FOREIGN KEY operation could cause a serious error. (Bug

#19471516, Bug #73650)

• InnoDB: In debug builds, an INSERT operation affecting compressed tables would raise a sync-related

assertion. (Bug #19295893)

MySQL 5.6 Release Notes

• InnoDB: Retrieval of multiple values with a single get command would return incorrect results instead of

an error message. The InnoDB memcached plugin does not currently support retrieval of multiple values

with a single get command. (Bug #19172212, Bug #72453)

• InnoDB: Attempting to perform operations on a timed out key would cause the memcached daemon to

crash and restart. (Bug #19172013, Bug #72586)

• InnoDB: With a transaction isolation level less than or equal to READ COMMITTED, gap locks were not

taken when scanning a unique secondary index to check for duplicates. As a result, duplicate check logic

failed allowing duplicate key values in the unique secondary index. (Bug #19140907)

References: This issue is a regression of: Bug #16133801.

• InnoDB: During recovery, a segmentation fault would occur when marking a table as corrupt. (Bug

#18942294)

References: This issue is a regression of: Bug #11830883.

• InnoDB: A failed in-place ALTER TABLE operation would leave behind nonunique temporary file names

in the data dictionary preventing future ALTER TABLE operations on the same table due to temporary

file name conflicts. To avoid this problem, temporary file names are made unique by appending a

static global number that is initialized to a random distributed 32-bit number using ut_time() and

ut_crc32(). The number is then incremented atomically for each assigned temporary file name.

Previously, temporary files were named using the format #sql-ibtid, where tid is the table ID.

Temporary files are now named using the format #sql-ibtid-inc, where tid is the table ID and inc

is the incremented number. (Bug #18734396, Bug #72594)

• InnoDB: In rare cases, the purge process would attempt to delete a secondary index record that was not

marked for deletion, resulting in an inconsistent secondary index. (Bug #18631496)

• InnoDB: srv_active_wake_master_thread() was called directly in innobase_commit and

innobase_prepare, waking up the master thread and incrementing srv_activity_count.

srv_active_wake_master_thread() should only be called after committing write

transactions, not after read-only transactions or rollbacks. This patch also replaces some calls to

srv_active_wake_master_thread() with calls to ib_wake_master_thread(). (Bug #18477009,

Bug #72137)

• InnoDB: An in-place ALTER TABLE operation on a table with a broken foreign key constraint could raise

an assertion. (Bug #16869435)

• InnoDB: Inserting a record into an InnoDB table with a key that falls between the maximum key of a full

page and the minimum key of the “next” page could result in unnecessary page splits and under-filled

pages. If the insert point is at the end of a page, InnoDB now attempts to insert to the next page before

splitting the page. (Bug #15923864, Bug #67718)

• Replication: After the fix for Bug #16861624, killing a multithreaded slave worker which was waiting for

a commit lock caused a debug assertion to fail. This fix ensures that such a situation can not occur. (Bug

#19311260)

• Replication: When committing a transaction, a flag is now used to check whether a thread has been

created, rather than checking the thread itself, which uses more resources, particularly when running the

server with master_info_repository=TABLE. (Bug #18684222)

References: See also: Bug #17967378.

• Replication: When using GTIDs with MASTER_AUTO_POSITION enabled, if an I/O thread was restarted

it failed with an ER_GTID_NEXT_TYPE_UNDEFINED_GROUP error due to a partial transaction not being

MySQL 5.6 Release Notes

correctly rolled back before resuming the I/O thread. This fix ensures that the partial transaction is

correctly rolled back. (Bug #18472603)

• Replication: When mysqlbinlog processed multiple binary log files into a single output file,

this file was not in a useful state for point-in-time recovery, when it failed with the error, When

@@SESSION.GTID_NEXT is set to a GTID, you must explicitly set it to a

different value after a COMMIT or ROLLBACK. Please check GTID_NEXT variable

manual page for detailed explanation. Current @@SESSION.GTID_NEXT is 'xyz'.

When mysqlbinlog processes a binary log containing GTIDs, it outputs SET gtid_next statements,

but gtid_next is set to undefined whenever a commit occurs; this left gtid_next undefined when the

server had finished processing the output from mysqlbinlog. When the next binary log file started with

one or more anonymous statements or transactions, the combination of gtid_next being left undefined at

the end of the first binary log and the second binary log containing anonymous transactions to the error

described previously (Error 1837, ER_GTID_NEXT_TYPE_UNDEFINED_GROUP).

To fix this issue, now, whenever mysqlbinlog encounters this situation, it inserts SET gtid_next =

AUTOMATIC if required to avoid leaving the previous binary log with gtid_next undefined.

In addition, as a result of this fix, mysqlbinlog no longer outputs session variable information for every

binary log; now, this value is printed only once unless it changes. (Bug #18258933, Bug #71695)

• Replication: When the I/O thread reconnected to a master using GTIDs and multithreaded slaves while

in the middle of a transaction, it failed to abort the transaction, leaving a partial transaction in the relay

log, and then retrieving the same transaction again. This occurred when performing a rotation of the

relay log. Now when reconnecting, the server checks before rotating the log in such cases, and waits

first for any ongoing transaction to complete. (Bug #17326020)

• Replication: The CLIENT_REMEMBER_OPTIONS flag for compressed slave connections is no longer

reset and all options are retained. This restores functionality of all options to compressed slave

connections. (Bug #72901, Bug #18923691, Bug #73324, Bug #19244772)

• Replication: When using row-based replication, setting a slave's slave_rows_search_algorithms

variable to HASH_SCAN caused an ER_KEY_NOT_FOUND error even though that record existed in the

storage layer. This fix ensures that the unique key for each record is correctly maintained and such a

situation does not occur. (Bug #72788, Bug #18860225)

• Replication: When using row-based replication, running a long transaction involving a large number

of events could trigger an Out of Memory (OOM) error if the slave's table structure was not compatible

with the master's table structure. Such an incompatible situation could occur if the table on the slave had

been manually changed, or when replicating between different MySQL versions that have different data

types. This OOM error was caused because the virtual temporary tables created for the row conversion

were not being freed until the end of the transaction, which was a problem when replicating large

numbers of events.

Starting with this version, such virtual tables are correctly freed during the conversion process. (Bug

#72610, Bug #18770469)

References: See also: Bug #19692387.

• Replication: The error messages generated when a duplicate server UUID causes issues during

replication have been improved. The slave error now identifies the duplicate server UUID and the master

error identifies the zombie thread that has been killed. (Bug #72578, Bug #18731211)

• Replication: When an event group was spanned across multiple relay log files, a slave could incorrectly

identify GTID-header group boundaries. This meant that when a transaction was retried, or if the SQL

thread was stopped in the middle of a transaction after some rotates, the Gtid_log_event was being

MySQL 5.6 Release Notes

silently skipped on the slave, and the transaction was logged with the slave's GTID. This problem also

impacted on using START SLAVE UNTIL MASTER_LOG_POS = log_pos; with GTIDs enabled.

If log_pos was in the middle of a transaction, the Gtid_log_event was not correctly detected

as the beginning of the transaction and replication stopped before this event. With this fix, threads

correctly detect that they are part of a group, and this is used to check if a Gtid_log_event is part of a

transaction. (Bug #72313, Bug #18652178, Bug #18306199)

• Replication: On a master that is using semisynchronous replication, where

rpl_semi_sync_master_wait_no_slave is enabled and rpl_semi_sync_master_timeout is

set to long timeout, killing the I/O thread could cause the server to hang on shutdown. This fix ensures

that if the dump thread finds that there no semisynchronous slaves connected to the master, the setting

of rpl_semi_sync_master_wait_no_slave is ignored and the shutdown proceeds correctly. (Bug

#71047, Bug #17879675)

• Replication: When using semisynchronous replication, if the binary log position was changed to a future

position on a slave then an assertion error was generated on the master. This fix ensures that in such

a situation the future position is correctly acknowledged and an error is instead generated on the slave.

(Bug #70327, Bug #17453826)

• Replication: When an SQL thread which was waiting for a commit lock was killed and restarted

it caused a transaction to be skipped on slave. This fix ensures that thread positions are correctly

persisted and transactions resume at the correct position. (Bug #69873, Bug #17450876)

• With DTrace support enabled, certain other compilation options could cause the build to fail. (Bug

#19506247)

• yaSSL client code did not validate the encryption size or session ID length, which could cause the client

to exit. (Bug #19463277, Bug #19463565)

• yaSSL could fail preauthorization if the client supplied inaccurate buffer lengths. (Bug #19370676, Bug

#19355577)

• Competition between threads could lead to timeout failure trying to rotate the audit log file. (Bug

#19184973)

• LPAD() and RPAD() could cause a server exit if the pad string argument was not well formed. (Bug

#18935421)

• The optimizer could create a zero-length column for a temporary table, causing a server exit. (Bug

#18928848)

• MOD for very small decimal right-hand arguments could cause a server exit. (Bug #18469276)

• The client library now includes a call to X509_verify_cert_error_string() in the SSL certificate

verification code, to be more robust in detecting invalid certificates. (Bug #18384260)

• If the left-hand-side of an IN predicate was a scalar subquery but returned no row, the server could exit.

(Bug #18223655, Bug #18447874)

• Sending a SIGQUIT or SIGINT signal to mysql could result in a glibc double free or corruption error.

(Bug #17297324)

• RPM Bundle tar file distributions did not include the shared compatibility library RPM. (Bug #74611,

Bug #19909411)

• On EL7, installation of MySQL from RPM packages could fail if postfix had previously been installed

using yum. (Bug #73507, Bug #19392051, Bug #19392149)

MySQL 5.6 Release Notes

• The query cache was not invalidated for a table when a CASCADE DELETE or CASCADE UPDATE

referential constraint was specified and the database name or table name contained special characters.

(Bug #72547, Bug #18710853)

• mysql_upgrade could fail if the mysql.user table contained multiple accounts with the same user

name and host name where the host name differed in lettercase. This is still not permitted, but now

mysql_upgrade prints a more informative error message to indicate the nature of the problem:

ERROR 1644 (45000): Multiple accounts exist for user_name, host_name

that differ only in Host lettercase; remove all except one of them

(Bug #72066, Bug #18415196)

• A simultaneous OPTIMIZE TABLE and online ALTER TABLE on the same InnoDB table could result in

deadlock. (Bug #71433, Bug #18110156)

• Invalid memory access could occur when using prepared statements if a mysql client connection was

lost after statement preparation was complete and there was at least one statement that was in initialized

state but not prepared yet. (Bug #70429, Bug #17512527)

• If the general query log or slow query log file was set to a FIFO or socket file, and the file reader

went away, the server stopped executing statements. Now the server detects such files, logs an error

message, and continues with the appropriate log disabled. (Bug #67088, Bug #14757009)

• LIKE matches failed for code points of HALF WIDTH KATAKANA in the sjis and cp932 character

sets. (Bug #47641, Bug #11755818)

Changes in MySQL 5.6.20 (2014-07-31, General Availability)

• Deprecation and Removal Notes

• DTrace Support

• InnoDB Notes

• MySQL Enterprise Notes

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

Deprecation and Removal Notes

• The timed_mutexes system variable has no effect and is deprecated. (Bug #18277305, WL #7436)

• The mysqlhotcopy utility is now deprecated and will be removed in a future MySQL version. Among

the reasons for this: It works only for the MyISAM and ARCHIVE storage engines; it works on Unix but not

Windows. Alternatives include mysqldump and MySQL Enterprise Backup. (WL #7854)

DTrace Support

• MySQL now includes DTrace support on Oracle Linux 6 or higher with UEK kernel. If DTrace is present,

server builds will detect it with no special CMake options required. For information about using DTrace on

MySQL, see Tracing mysqld Using DTrace. (WL #7894)

MySQL 5.6 Release Notes

InnoDB Notes

• Important Change: Redo log writes for large, externally stored BLOB fields could overwrite the most

recent checkpoint. The 5.6.20 patch limits the size of redo log BLOB writes to 10% of the redo log file

size. The 5.7.5 patch addresses the bug without imposing a limitation. For MySQL 5.5, the bug remains

a known limitation.

As a result of the redo log BLOB write limit introduced for MySQL 5.6, the innodb_log_file_size

setting should be 10 times larger than the largest BLOB data size found in the rows of your tables plus

the length of other variable length fields (VARCHAR, VARBINARY, and TEXT type fields). No action is

required if your innodb_log_file_size setting is already sufficiently large or your tables contain no

BLOB data.

Note

In MySQL 5.6.22, the redo log BLOB write limit is relaxed to 10% of the total redo

log size (innodb_log_file_size * innodb_log_files_in_group).

(Bug #16963396, Bug #19030353, Bug #69477)

MySQL Enterprise Notes

• The audit log plugin included in MySQL Enterprise Edition now has the capability of filtering audited

events based on user account and event status. Several new system variables provide DBAs with

filtering control. In addition, audit log plugin reporting capability has been improved by the addition of

several status variables.

Incompatible configuration change: audit_log_policy can be set at server startup (as before), but

at runtime is now a read-only variable. This is due to the introduction of two new system variables,

audit_log_connection_policy and audit_log_statement_policy, that provide finer

control over logging policy and that can be set either at startup or at runtime. If you continue to use

audit_log_policy at startup instead of the other two variables, the server uses its value to set those

variables.

For more information, see Configuring Audit Logging Characteristics, and Audit Log Plugin Status

Variables. (WL #7219)

Security Notes

• The linked OpenSSL library for the MySQL 5.6 Commercial Server has been updated from version

1.0.1g to version 1.0.1h. Versions of OpenSSL prior to and including 1.0.1g are reported to be vulnerable

to CVE-2014-0224.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server 5.6, which

uses the yaSSL library instead. (Bug #18917858)

Functionality Added or Changed

• Replication: The new system variable binlogging_impossible_mode controls what happens if the

server cannot write to the binary log, for example, due to a file error. For backward compatibility, the

default for binlogging_impossible_mode is IGNORE_ERROR, meaning the server logs the error,

halts logging, and continues updates to the database. Setting this variable to ABORT_SERVER makes the

server halt logging and shut down if it cannot write to the binary log. (Bug #51014, Bug #11758766)

MySQL 5.6 Release Notes

• New Debian7, Ubuntu12.04, and Ubuntu14.04 distribution support that was introduced with 5.6.17 now

comes with the platform-specific packaging source placed under the packaging directory, in the deb-

precise, deb-wheezy, and deb-trusty directories. (Bug #19020385)

• CMake support was updated to handle CMake version 3. (Bug #19001781)

• Support for LinuxThreads has been removed from the source code. LinuxThreads was superseded by

NPTL in Linux 2.6. (Bug #17007529, Bug #72888, Bug #18913935)

• By default, mysql_install_db creates a my.cnf file in the installation base directory using a

template. This may be undesireable for some deployments. To enable this behavior to be suppressed,

mysql_install_db now supports a --keep-my-cnf option to preserve any existing my.cnf file and

not create a new my.cnf file. (Bug #71600, Bug #18205019)

Bugs Fixed

• Important Change; Replication: A DROP TABLE statement may be divided into multiple statements

before it is sent to the binary log if it contains regular (not temporary) tables and temporary tables, or

if it contains temporary tables using both transactional and non-transactional storage engines. Now,

when using GTIDs, DROP TABLE statements affecting these combinations of tables are no longer

allowed unless the value of the gtid_next system variable is AUTOMATIC. This is because, with GTIDs

enabled on the server, issuing a DROP TABLE in the cases just described while having only one GTID

associated with each statement (the SQL thread does this following SET gtid_next='uuid:number')

causes problems when there are not enough GTIDs for assignment to all the resulting statements

following the division of the original DROP TABLE.

A DROP TABLE statement might be split due to the behavior of the statement with respect to the current

transaction varying, depending on table characteristics, as follows:

• DROP TABLE of a regular (not temporary) table is committed immediately

• DROP TABLE of a temporary table using a transactional storage engine is committed with the current

transaction (following COMMIT)

• DROP TABLE of a temporary table that uses a nontransactional storage engine is committed

immediately

Naming all three of these types of tables in a single DROP TABLE statement causes the MySQL server

to divide the original statement into three separate DROP TABLE statements in the binary log. If GTIDs

are enabled but the value of gtid_next is not AUTOMATIC, issuing a DROP TABLE statement that

mixes any of the table types described previously causes the server to have an insufficient number

of GTIDs to write with all of the resulting statements into the binary log. In addition, DROP TABLE IF

EXISTS is always written in the binary log for all tables specified in the statement, even if some or all of

the tables do not exist.

Because temporary tables are handled differently by DROP TABLE depending on whether they use a

transactional or nontransactional storage engine, any tables named by a DROP TEMPORARY TABLE

statement that do not exist are assumed to be transactional. This means that, if a DROP TEMPORARY

TABLE with two nontransactional temporary tables is issued on the master, it would writes only one

DROP TABLE statement naming both tables. If one of the temporary tables no longer exists on the slave,

then, when the SQL thread executes the statement, it tries to divide it into multiple statements due to

it affecting a nontransactional (but existing) temporary table and a nonexistent transactional temporary

table; this leads to problems because the SQL thread has only one GTID for the original DROP TABLE

statement but must write two DROP TABLE statements in the binary log.

MySQL 5.6 Release Notes

In addition, when the slave dropped temporary tables after detecting that the master had restarted, it

logged one DROP TABLE statement per pseudo-thread and per database, but combined temporary

tables using transactional and nontransactional storage engines in a single DROP TABLE statement.

Now, we throw an error in the client session if gtid_next is set to a uuid:number value and a DROP

TABLE statement is issued mixing any of the table types described previously.

In addition, we now group the nonexistent temporary tables and assume them to be transactional only

if at least one transactional temporary table is dropped by the statement. If no transactional temporary

tables are dropped, any nonexistent temporary tables are assumed to be nontransactional temporary

tables.

The slave now also handles dropping of temporary tables correctly in the event of the restart by the

master. (Bug #17620053)

• InnoDB: Opening a parent table that has thousands of child tables could result in a long semaphore wait

condition. (Bug #18806829)

• InnoDB: On mysqld start, specifying multiple data files using the innodb_data_file_path

option would return a Space id in fsp header error after data is written to the second file. (Bug

#18767811)

• InnoDB: For single item full-text searches, deleted documents were included in inverse document

frequency (IDF) calculations. (Bug #18711306, Bug #72548)

• InnoDB: A DELETE operation on a table with full-text search indexes raised an assertion. (Bug

#18683832)

References: See also: Bug #14639605.

• InnoDB: When InnoDB is built as a shared library, attempting to load the InnoDB full-text search (FTS)

INFORMATION_SCHEMA plugin would fail with a Can't open shared library 'ha_innodb.so'

error. (Bug #18655281, Bug #70178)

• InnoDB: When calling the memcached flush_all command, InnoDB attempts to initialize a

connection and a transaction. If the transaction is in TRX_STATE_NOT_STARTED state, InnoDB failed to

set CONN_DATA->CRSR_TRX to NULL, resulting in a serious error. (Bug #18652854)

• InnoDB: A regression introduced in MySQL 5.6.5 would cause full-text search index tables to be created

in the system tablespace (space 0) even though innodb_file_per_table was enabled. (Bug

#18635485)

• InnoDB: The InnoDB memcached plugin would call plugin_del without acquiring the lock_plugin

mutex. This bug fix also addresses a race condition in ib_cursor_delete_row. (Bug #18409840)

• InnoDB: The fix for Bug#16418661 added superfluous buf_flush_list() logic to InnoDB startup

code. (Bug #17798076, Bug #70899)

References: This issue is a regression of: Bug #16418661.

• InnoDB: A race condition in fts_get_next_doc_id resulted in Duplicate FTS_DOC_ID and

Cannot find index FTS_DOC_ID_INDEX in InnoDB index translation table errors. (Bug

#17447086, Bug #70311)

References: See also: Bug #16469399.

MySQL 5.6 Release Notes

• InnoDB: Due to differences in memory ordering on different processor types, some mutex and read-

write lock flags were not read consistently. (Bug #11755438, Bug #47213)

• Partitioning: Selecting from a table having multiple columns in its primary key and partitioned by LIST

COLUMNS(R), where R was the last (rightmost) column listed in the primary key definition, returned an

incorrect result. (Bug #17909699, Bug #71095)

• Replication: mysqlbinlog --raw did not check for errors caused by failed writes, which could result in

silent corruption of binary logs. Now in such cases it stops with an error. (Bug #18742916, Bug #72597)

• Replication: When a slave worker thread tried to execute a statement that was too large, the resulting

error caused a crash. Now in such cases, the error is truncated to fit the size of the buffer. (Bug

#18563480)

• Replication: When using row-based replication, updating or deleting a row on the master that did not

exist on the slave led to failure of the slave when it tried to process the change. This problem occurred

with InnoDB tables lacking a primary key. (Bug #18432495, Bug #72085)

• Replication: Quotation marks were not always handled correctly by LOAD DATA when written into the

binary log. (Bug #18207212, Bug #71603)

• Replication: Beginning in MySQL 5.6.20, when a user specified AUTO_INCREMENT value falls outside

of the range between the current AUTO_INCREMENT value and the sum of the current and number of

rows affected values it is replicated correctly. In previous versions, an error was generated by the slave

even if the user specified AUTO_INCREMENT value fell outside of the range. (Bug #17588419, Bug

#70583)

• Replication: On Windows, mysqldump failed if the error log file was deleted (missing) from the active

MySQL server. (Bug #17076131)

• Replication: Client applications should be able to set the BINLOG_DUMP_NON_BLOCK flag in the initial

handshake packet (COM_BINLOG_DUMP). Clients connecting to a server issuing a COM_BINLOG_DUMP

with the flag unset do not get an EOF when the server has sent the last event in the binary log, which

causes the connection to block. This flag, which was removed in error in MySQL 5.6.5, is now restored in

the current release.

As part of this fix, a new --connection-server-id option is added to mysqlbinlog. This option

can be used by the client to test a MySQL server for the presence of this issue. (Bug #71178, Bug

#18000079)

• Replication: Uninstalling and reinstalling semisynchronous replication plugins while semisynchronous

replication was active caused replication failures. The plugins now check whether they can be

uninstalled and produce an error if semisynchronous replication is active. To uninstall the master-side

plugin, there must be no semisynchronous slaves. To uninstall the slave-side plugin, there must be no

semisynchronous I/O threads running. (Bug #70391, Bug #17638477)

• Replication: Replication of tables that contained temporal type fields (such as TIMESTAMP, DATETIME,

and TIME) from different MySQL versions failed due to incompatible TIMESTAMP types. The fractional

TIMESTAMP format added in MySQL 5.6.4 was not being correctly converted. You can now replicate

a TIMESTAMP in either format correctly according to the slave_type_conversions variable. (Bug

#70124, Bug #17532932)

• Replication: A group of threads involved in acquiring locks could deadlock when the following events

occurred:

1. Dump thread reconnects from slave; on master, a new dump thread tries to kill zombie dump

threads; having acquired the thread's LOCK_thd_data, it is about to acquire LOCK_log.

MySQL 5.6 Release Notes

2. Application thread executing show binary logs, having acquired LOCK_log and about to acquire

LOCK_index.

3. Application thread executing PURGE BINARY LOGS; having acquired LOCK_index, it is about to

acquire LOCK_thread_count.

4. Application thread executing SHOW PROCESSLIST (or SELECT * FROM

INFORMATION_SCHEMA.PROCESSLIST), having acquired LOCK_thread_count and about to

acquire the zombie dump thread's LOCK_thd_data.

This leads to the 4 threads deadlocking in the same order which the threads have been listed here.

This problem arises because there are ordering rules for LOCK_log and LOCK_index, as well as rules

for ordering LOCK_thread_count and LOCK_thd_data, but there are no rules for ordering across

these two sets of locks. This was because the internal mysqld_list_processes() function invoked

by SHOW PROCESSLIST acquired LOCK_thread_count for the complete lifetime of the function as

well as acquiring and releasing each thread's LOCK_thd_data. Now this function takes a copy of

the threads from the global thread list and performs its traversal on these, and only after releasing

LOCK_thread_count. During this traversal, removal from the global thread list is blocked using

LOCK_thd_remove such that the copies that would otherwise be destroyed by the removal remain valid

during traversal. The locking order following this fix is shown here:

LOCK_thd_remove -> LOCK_thd_data -> LOCK_log -> LOCK_index -> LOCK_thread_count

(Bug #69954, Bug #17283409)

References: See also: Bug #73475, Bug #19364731, Bug #19365180.

• When a SELECT included a derived table in a join in its FROM list and the SELECT list included

COUNT(DISTINCT), the COUNT() returned 1 even if the underlying result set was empty. (Bug

#18853696)

References: This issue is a regression of: Bug #11760197.

• Enabling optimizer trace could cause a server exit for queries with a subquery in a HAVING clause. (Bug

#18791851)

• SHA and MD5 functions failed for operations using the internal filename character set and could cause

a server exit. (Bug #18786138)

• Large arguments passed to mysqldump could lead to buffer overflow and program exit. (Bug

#18779944)

• After a metadata change, a reprepared trigger could cause a server exit or prune an incorrect partition.

(Bug #18684393)

• ALTER TABLE on a partitioned table could result in the wrong storage engine being written into the

table's .frm file and displayed in SHOW CREATE TABLE. (Bug #18618561)

• Compiler flags were not passed to DTrace, causing problems for 32-bit builds cross-compiled on 64-bit

platforms. (Bug #18593044)

• With the max_heap_table_size system variable set to a large value (20GB), creation of a temporary

table or a table using the MEMORY storage engine caused a server exit. (Bug #18463911)

MySQL 5.6 Release Notes

• If MySQL was built with the -DINSTALL_LIBDIR=lib64 option, mysql_config did not work if the

MySQL package was unpacked into a location with a different installation prefix. Also, mysql_config

did not work for some RPM builds because it used an incorrect installation prefix. (Bug #18382225)

• For debug builds, a 0x00 character in a full-text query string that used the ujis_japanese_ci,

utf8mb4_turkish_ci, or eucjpms_bin collation could raise an assertion. (Bug #18277305)

• yaSSL code had an off-by-one error in certificate decoding that could cause buffer overflow.

yaSSL code had an opendir() without a corresponding closedir(). (Bug #18178997, Bug

#17201924)

• mysqladmin password masked the old password given on the command line, but not the new

password. (Bug #18163964)

• For full-text queries on InnoDB tables, attempts to access deleted document IDs could lead to a server

exit. (Bug #18079671)

• MyISAM temporary files could be used to mount a code-execution attack. (Bug #18045646)

• For queries that selected from the events_statements_current Performance Schema table, adding

an ORDER BY clause could produce incorrect results. (Bug #17729044)

• If a query had both MIN()/MAX() and aggregate_function(DISTINCT) (for example,

SUM(DISTINCT)) and was executed using Loose Index Scan, the result values of MIN()/MAX() were

set improperly. (Bug #17217128)

• For UNION statements, the rows-examined value was calculated incorrectly. This was manifest as

too-large values for the ROWS_EXAMINED column of Performance Schema statement tables (such as

events_statements_current). (Bug #17059925)

• Clients could determine based on connection error message content whether an account existed. (Bug

#16513435, Bug #17357528, Bug #19273967)

• An assertion could be raised when creating a index on a prefix of a TINYBLOB or GEOMETRY column in

an InnoDB column. (Bug #16368875, Bug #18776592, Bug #17665767)

• Use of a nonmultibyte algorithm for skipping leading spaces in multibyte strings could cause a server

exit. (Bug #12368495, Bug #18315770)

• Binary MySQL distributions for OS X 10.8 and up now bundle the MySQL.prefPane and

MySQLStartupItem.pkg tools into the main package as configurable options instead of separate

packages. (Bug #74123, Bug #19701502)

• A new CMake option, SUNPRO_CXX_LIBRARY, enables linking against libCstd instead of stlport4

on Solaris 10 or later. This works only for client code because the server depends on C++98. Example

usage:

cmake -DWITHOUT_SERVER=1 -DSUNPRO_CXX_LIBRARY=Cstd

(Bug #72352, Bug #18605389)

• mysql_config_editor exited when given an empty argument to the --login-path option. (Bug

#71837, Bug #18311024, Bug #18830493)

• Upgrades using RPM packages could change the ownership of an installation directory. (Bug #71715,

Bug #18281535)

• Proxy users were unable to execute statements if the proxied user password had expired. (Bug #71337,

Bug #18057562)

MySQL 5.6 Release Notes

• MySQL did not compile with Bison 3. (Bug #71250, Bug #18017820, Bug #18978946)

• Deadlock could occur if three threads simultaneously performed INSTALL PLUGIN, SHOW VARIABLES,

and mysql_change_user(). (Bug #71236, Bug #18008907, Bug #72870, Bug #18903155)

• If there was a predicate on a column referenced by MIN() or MAX() and that predicate was not present

in all the disjunctions on key parts earlier in the compound index, Loose Index Scan returned an

incorrect result. (Bug #71097, Bug #17909656)

• Client auto-reconnect did not work for clients linked against libmysqlclient, even with

MYSQL_OPT_RECONNECT enabled.

Also, if a FEDERATED table was accessed after wait_timeout expired, a Lost connection to

MySQL server error occurred without an attempt to re-establish the connection. (Bug #70026, Bug

#17309863, Bug #14874, Bug #11745408)

• File permissions and line endings of several test and configuration files were made more consistent to

avoid warnings from package checkers. (Bug #68521, Bug #16415173, Bug #16395459, Bug #68517,

Bug #16415032, Bug #71112, Bug #17919313, Bug #71113, Bug #17919422)

• Configuring with cmake -DWITHOUT_SERVER to build clients without the server failed for builds outside

of the source tree. (Bug #66000, Bug #14367046)

• For a view defined on a UNION, the server could create an invalid view definition. (Bug #65388, Bug

#14117018, Bug #72018, Bug #18405221)

• With big_tables enabled, queries that used COUNT(DISTINCT) on a simple join with a constant

equality condition on a non-duplicate key returned incorrect results. (Bug #52582, Bug #11760197)

References: See also: Bug #18853696.

Changes in MySQL 5.6.19 (2014-05-30, General Availability)

There is no MySQL Community Server 5.6.18. That version number was used for an out-of-schedule

release of MySQL Enterprise Edition to address the OpenSSL “Heartbleed” issue. This issue did not affect

MySQL Community Edition because it uses yaSSL, not OpenSSL, so a new release of the Community

Server was not needed, and 5.6.17 is followed by 5.6.19.

• Deprecation and Removal Notes

• Functionality Added or Changed

• Bugs Fixed

Deprecation and Removal Notes

• The mysqlbug, mysql_waitpid, and mysql_zap utilities have been deprecated and will be removed

in MySQL 5.7. (WL #7689, WL #7826)

Functionality Added or Changed

• The obsolete and unmaintained charset2html utility has been removed from MySQL distributions.

(Bug #71897, Bug #18352347)

MySQL 5.6 Release Notes

Bugs Fixed

• InnoDB: After upgrading from 5.6.10 to MySQL versions up to and including MySQL 5.6.18, InnoDB

would attempt to rename obsolete full-text search auxiliary tables on server startup, resulting in an

assertion failure. (Bug #18634201, Bug #72079)

• InnoDB: With persistent statistics enabled, SHOW TABLE STATUS output and the TABLE_ROWS column

of INFORMATION_SCHEMA.TABLES could report an incorrect number of table rows for tables with

externally stored pages. (Bug #18384390)

• InnoDB: The fix for Bug#17699331 caused a high rate of read/write lock creation and destruction which

resulted in a performance regression. (Bug #18345645, Bug #71708)

References: This issue is a regression of: Bug #17699331.

• InnoDB: For each insert, memset would be called three times to allocate memory for system fields. To

reduce CPU usage, the three memset calls are now combined into a single call. (Bug #17858679, Bug

#71014)

• InnoDB: Enabling the InnoDB Table Monitor would result in a ib_table->stat_initialized

assertion failure. (Bug #17039528, Bug #69641)

• InnoDB: With innodb_max_dirty_pages_pct=0 buffer pool flushing would not be initiated until the

percentage of dirty pages reached at least 1%, which would leave up to 1% of dirty pages unflushed.

(Bug #13029450, Bug #62534)

• Replication: Log rotation events could cause group_relay_log_pos to be moved forward incorrectly

within a group. This meant that, when the transaction was retried, or if the SQL thread was stopped

in the middle of a transaction following one or more log rotations (such that the transaction or group

spanned multiple relay log files), part or all of the group was silently skipped.

This issue has been addressed by correcting a problem in the logic used to avoid touching the

coordinates of the SQL thread when updating the log position as part of a relay log rotation whereby it

was possible to update the SQL thread's coordinates when not using a multithreaded slave, even in the

middle of a group. (Bug #18482854)

• Replication: When running the server with --gtid-mode=ON, STOP SLAVE followed

by START SLAVE resulted in a mismatch between the information provided by

INFORMATION_SCHEMA.INNODB_TEMP_TABLE_INFO and the Slave_open_temp_tables

status variable: the INNODB_TEMP_TABLE_INFO table showed that no temporary tables existed, but

Slave_open_temp_tables had a nonzero value. (Bug #18364070)

References: See also: Bug #18236612.

• Replication: In certain cases, the server mishandled triggers and stored procedures that tried to modify

other tables when called by CREATE TABLE ... SELECT. This is now handled correctly as an error.

(Bug #18137535)

• Replication: When used on a table employing a transactional storage engine, a failed TRUNCATE

TABLE was still written to the binary log and thus replayed on the slave. This could lead to inconsistency

when the master retained data that was removed on the slave.

Now in such cases TRUNCATE TABLE is logged only when it executes successfully. (Bug #17942050,

Bug #71070)

• Replication: The server did not always handle the auto.cnf file correctly in cases where this file's

permissions were incorrect. (Bug #17786581, Bug #70891)

MySQL 5.6 Release Notes

• Replication: When the binary log was rotated due to receipt of a SIGHUP signal, the new binary log

did not contain the Previous_gtid_event required for subsequent processing of that binary log's

GTID events. Now when SIGHUP is received, steps are taken to insure that the server writes the

necessary Previous_gtid_event to the new log before writing any GTID events to the new log. (Bug

#17026898)

• Replication: When gtid_mode=ON, and a transaction is filtered out on the slave, the GTID of the

transaction is still logged on the slave as an “empty” transaction (consisting of a GTID followed

immediately by BEGIN and then COMMIT). This is necessary to prevent the transaction from being

retransmitted the next time the slave reconnects or is involved in a failover. The current fix addresses

two issues relating to such “empty” transactions:

• No empty transaction was generated for CREATE TEMPORARY TABLE or DROP TEMPORARY TABLE

statements.

• If the slave used a database filter (--replicate-do-db or --replicate-ignore-db option), no

empty transaction was generated.

(Bug #71376, Bug #18095502, Bug #18145032)

• The server could fail to properly reprepare triggers that referred to another table after that table was

truncated. (Bug #18596756, Bug #72446, Bug #18665853)

• For indexes on prefixes or character string columns, index corruption could occur for assignment of

binary data to the column due to improper character counting. (Bug #18359924)

• Certain INFORMATION_SCHEMA queries could cause a server exit. (Bug #18319790)

• Solaris-specific scripts were included in and installed by non-Solaris packages. (Bug #18305641)

• innobase_strnxfrm() wrote one byte too many. (Bug #18277082)

• EXPLAIN on a query with an EXISTS subquery containing a UNION could cause a server exit.

Multiple executions of a prepared EXPLAIN on a UNION of subqueries could cause a server exit. (Bug

#18167356)

• Concurrent execution of a FLUSH TABLES operation and a stored program that used a cursor could

cause a server exit. (Bug #18158639)

• The client library could cause clients to exit due to incorrectly mapping the client error number to the

corresponding message, if reallocation of packet buffer memory occurred. (Bug #18080920)

• Calling mysql_get_server_version() with an invalid connection handler argument caused the

client to exit. Now it returns 0 and reports a CR_COMMANDS_OUT_OF_SYNC error. (Bug #18053212)

• On Windows, calling mysql_thread_init() call without mysql_init() caused the client to exit.

windows. Now it returns a nonzero result because it is an error to call mysql_thread_init() before

the client library is initialized with mysql_library_init(). (Bug #17514920)

• mysqldump could create table definitions in the dump file that resulted in Too many columns errors

when reloading the dump file. (Bug #17477959)

• The optimizer trace could cause a server exit in cases where a subquery was transformed away. (Bug

#17458054)

• The Debug Sync facility could lose a signal, leading to a spurious ER_DEBUG_SYNC_TIMEOUT error.

(Bug #14765080, Bug #18221750)

MySQL 5.6 Release Notes

• A statement of the following form broke row-based replication because it created a table having a field of

data type BIGINT with a display width of 3000, which is beyond the maximum acceptable value of 255:

CREATE TABLE t1 AS SELECT REPEAT('A',1000) DIV 1 AS a;

(Bug #71179, Bug #17994219)

• CMake produced not-useful warnings about INTERFACE_LINK_LIBRARIES policy. (Bug #71089, Bug

#17905155, Bug #17894997)

• Updates could fail to update all applicable rows in cases where multiple key values were identical except

for trailing spaces. (Bug #69684, Bug #17156940)

• On Windows, REPAIR TABLE and OPTIMIZE TABLE failed for MyISAM tables with .MYD files larger

than 4GB. (Bug #69683, Bug #17235179)

• Compilation problems were fixed for errors reported by Clang and gcc when compiling in C++11 mode.

(Bug #66803, Bug #14631159)

• LOAD DATA LOCAL could use all CPU if import errors occurred when there were no line delimiters. (Bug

#51840, Bug #11759519)

Changes in MySQL 5.6.18 (2014-04-11, General Availability)

A known limitation of this release:

Note

If you have InnoDB tables with full-text search indexes and you are upgrading from

MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server

will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.

As a workaround, remove full-text search indexes prior to upgrading and rebuild full-

text search indexes after the upgrade is completed.

• Security Notes

• Bugs Fixed

Security Notes

• The MySQL 5.6 Commercial Server has been updated to use OpenSSL version 1.0.1g, which has been

publicly reported as not vulnerable to CVE-2014-0160. Please see Oracle Note #1645479.1 for further

details.

The MySQL 5.6 Community Server is built using the yaSSL cryptographic software library instead of

OpenSSL. Oracle-produced MySQL 5.6 Community Server binaries use YaSSL libraries which have

been reported as not affected by CVE-2014-0160. Users of MySQL Server binaries produced by parties

other than Oracle should seek a vulnerability assessment from their respective binary providers.

Since the only change in MySQL Server 5.6.18 is the inclusion of OpenSSL libraries publicly reported

as unaffected by CVE-2014-0160, and since Oracle-produced MySQL Community builds do not include

OpenSSL libraries known to be affected by CVE-2014-0160, Oracle is not producing builds for MySQL

Community Server for version 5.6.18. This means that MySQL Community Server is skipping version

5.6.18. (Bug #18533200)

MySQL 5.6 Release Notes

Bugs Fixed

• Executing a correlated subquery on an ARCHIVE table which has an AUTO_INCREMENT column caused

the server to hang. (Bug #18065452)

Changes in MySQL 5.6.17 (2014-03-27, General Availability)

A known limitation of this release:

Note

If you have InnoDB tables with full-text search indexes and you are upgrading from

MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server

will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.

As a workaround, remove full-text search indexes prior to upgrading and rebuild full-

text search indexes after the upgrade is completed.

• Deprecation and Removal Notes

• Functionality Added or Changed

• Bugs Fixed

Deprecation and Removal Notes

• Incompatible Change: The ERROR_FOR_DIVISION_BY_ZERO, NO_ZERO_DATE, and

NO_ZERO_IN_DATE SQL modes now are deprecated and setting the sql_mode value to include any of

them generates a warning. In MySQL 5.7, these modes do nothing. Instead, their effects are included

in the effects of strict SQL mode (STRICT_ALL_TABLES or STRICT_TRANS_TABLES). The motivation

for the change in MySQL 5.7 is to reduce the number of SQL modes with an effect dependent on strict

mode and make them part of strict mode itself.

To make advance preparation for an upgrade to MySQL 5.7, see SQL Mode Changes in MySQL 5.7.

That discussion provides guidelines to assess whether your applications will be affected by the SQL

mode changes in MySQL 5.7. (WL #7467)

• The msql2mysql, mysql_convert_table_format, mysql_find_rows,

mysql_fix_extensions, mysql_setpermission, and mysqlaccess utilities are now deprecated

and will be removed in MySQL 5.7. (Bug #27482, Bug #69012, Bug #69014, Bug #69015, Bug #69016,

Bug #69017, Bug #11746603, Bug #16699248, Bug #16699279, Bug #16699284, Bug #16699317, Bug

#18179576)

• The IGNORE clause for ALTER TABLE is now deprecated and will be removed in a future version of

MySQL. ALTER IGNORE TABLE causes problems for replication, prevents online ALTER TABLE for

unique index creation, and causes problems with foreign keys (rows removed in the parent table). (WL

#7395)

Functionality Added or Changed

• Incompatible Change: The AES_ENCRYPT() and AES_DECRYPT() functions now permit control of the

block encryption mode and take an optional initialization vector argument:

• The new block_encryption_mode system variable controls the mode for block-based encryption

algorithms. Its default value is aes-128-ecb, which signifies encryption using a key length of 128 bits

and ECB mode.

MySQL 5.6 Release Notes

• An optional init_vector argument provides an initialization vector for encryption modes that require

it:

AES_ENCRYPT(str,key_str[,init_vector])

AES_DECRYPT(crypt_str,key_str[,init_vector])

• A random string of bytes to use for the initialization vector can be produced by calling the new

RANDOM_BYTES() function.

For more information, see Encryption and Compression Functions.

These changes make statements that use AES_ENCRYPT() or AES_DECRYPT() unsafe for statement-

based replication and they cannot be stored in the query cache. Queries that use RANDOM_BYTES() are

unsafe for statement-based replication and cannot be stored in the query cache. (WL #6781)

• InnoDB: Online DDL support is extended to the following operations for regular and partitioned InnoDB

tables:

• OPTIMIZE TABLE

• ALTER TABLE ... FORCE

• ALTER TABLE ... ENGINE=INNODB (when run on an InnoDB table)

Online DDL support reduces table rebuild time and permits concurrent DML. See InnoDB and Online

DDL.

(Bug #13975225)

• Solaris: On Solaris, mysql_config --libs now includes -R/path/to/library so that libraries

can be found at runtime. (Bug #18235669)

• mysql_install_db provides a more informative diagnostic message when required Perl modules are

missing. (Bug #69844, Bug #18187451)

Bugs Fixed

• Incompatible Change: Old clients (older than MySQL 5.5.7) failed to parse authentication data correctly

if the server was started with the --default-authentication-plugin=sha256_password option.

Note

As a result of this bug fix, MySQL 5.6.16 clients cannot connect to a 5.6.17 server

using an account that authenticates with the sha256_password plugin, nor

can 5.6.17 clients connect to a 5.6.16 server. Similarly, MySQL 5.7.3 clients

cannot connect to a 5.7.4 server using an account that authenticates with the

sha256_password plugin.

(Bug #17495562)

• Important Change; InnoDB; Partitioning: The FLUSH TABLES statement's FOR EXPORT option is

now supported for partitioned InnoDB tables. (Bug #16943907)

• InnoDB: Running a SELECT on a partitioned table caused a memory access violation in memcpy().

(Bug #18383840)

References: See also: Bug #18167648.

MySQL 5.6 Release Notes

• InnoDB: For full-text queries, a failure to check that num_token is less than max_proximity_item

could result in an assertion. (Bug #18233051)

• InnoDB: An invalid memmove in fts_query_fetch_document would cause a serious error. (Bug

#18229433)

• InnoDB: innodb_ft_result_cache_limit now has a hardcoded maximum value of 4294967295

bytes or (2**32 -1). The maximum value was previously defined as the maximum value of ulong. (Bug

#18180057, Bug #71554)

• InnoDB: An UPDATE resulted in a memory access error in lock_rec_other_trx_holds_expl. The

transaction list (trx_sys->rw_trx_list) was traversed without acquiring the transaction subsystem

mutex (trx_sys->mutex). (Bug #18161853)

• InnoDB: InnoDB failed to restore a corrupt first page of a system tablespace data file from the

doublewrite buffer, resulting in a startup failure. (Bug #18144349, Bug #18058884)

• InnoDB: A regression introduced by Bug #14329288 would result in a performance degradation when a

compressed table does not fit into memory. (Bug #18124788, Bug #71436)

References: This issue is a regression of: Bug #14329288.

• InnoDB: The maximum value for innodb_thread_sleep_delay is now 1000000

microseconds. The previous maximum value (4294967295 microseconds on 32-bit and

18446744073709551615 microseconds on 64-bit) was unnecessarily large. Because

the maximum value of innodb_thread_sleep_delay is limited by the value set for

innodb_adaptive_max_sleep_delay (when set to a nonzero value), the maximum

value for innodb_thread_sleep_delay is now the same as the maximum value for

innodb_adaptive_max_sleep_delay. (Bug #18117322)

• InnoDB: Attempting to uninstall the InnoDB memcached plugin while the InnoDB memcached plugin is

still initializing would kill the InnoDB memcached daemon thread. Uninstall should wait until initialization

is complete. (Bug #18038948)

• InnoDB: A full-text tokenizer thread would terminate with an incorrect error message. (Bug #18021306)

• InnoDB: In debug builds, creating a unique index on a binary column, with input data containing

duplicate keys, would cause an assertion. (Bug #18010711)

• InnoDB: The srv_monitor_thread would crash in the lock_print_info_summary() function due

to a race condition between the srv_monitor_thread and purge coordinator thread. (Bug #17980590,

Bug #70430)

• InnoDB: Attempting to add an invalid foreign key when foreign key checking is disabled

(foreign_key_checks=0) would cause a serious error. (Bug #17666774)

• InnoDB: For debug builds, the table rebuilding variant of online ALTER TABLE, when run on tables with

BLOB columns, would cause an assertion in the row_log_table_apply_update function. For normal

builds, a DB_PRODUCTION error would be returned. (Bug #17661919)

• InnoDB: When creating a table there are a minimum of three separate inserts on the

mysql.innodb_index_stats table. To improve CREATE TABLE performance, there is now a single

COMMIT operation instead of one for each insert. (Bug #17323202, Bug #70063)

• InnoDB: The server would halt with an assertion in lock_rec_has_to_wait_in_queue(lock) due

to a locking-related issue and a transaction being prematurely removed from trx_sys->rw_trx_set.

(Bug #17320977)

MySQL 5.6 Release Notes

• InnoDB: Server shutdown would result in a hang with the following message written to the error log:

“[NOTE] InnoDB: Waiting for purge thread to be suspended.” (Bug #16495065)

• InnoDB: InnoDB failed to start when innodb_data_file_path specified the data file size in kilobytes

by appending K to the size value. (Bug #16287752)

• InnoDB: An insert buffer merge would cause an assertion error due to incorrectly handled ownership

information for externally stored BLOBs.

InnoDB: Assertion failure in thread thread_num in file ibuf0ibuf.cc line 4080

InnoDB: Failing assertion: rec_get_deleted_flag(rec, page_is_comp(page))

(Bug #14668683)

• InnoDB: Decreasing the auto_increment_increment value would have no affect on the next auto-

increment value. (Bug #14049391, Bug #65225)

• Partitioning: When the index_merge_intersection flag (enabled by default) or the

index_merge_union flag was enabled by the setting of the optimizer_switch system variable,

queries returned incorrect results when executed against partitoned tables that used the MyISAM storage

engine, as well as partitioned InnoDB tables that lacked a primary key. (Bug #18167648)

References: See also: Bug #16862316, Bug #17588348, Bug #17648468.

• Replication: The MASTER_SSL_CRL and MASTER_SSL_CRLPATH options are not available when using

yaSSL; MySQL Replication now sets these to NULL automatically whenever yaSSL is enabled. (Bug

#18165937)

• Replication: Setting slave_parallel_workers to 1 or greater and starting the slave caused the

slave SQL thread to use but not release memory until the slave was restarted with STOP SLAVE and

START SLAVE. (Bug #18001777, Bug #71197)

• Replication: When a slave was configured with replication filters and --log-warnings=2, every

statement which was filtered caused an entry to be written in the error log. For busy servers which

generated many statements to be filtered, the result was that the error log could quickly grow to many

gigabytes in size. Now a throttle is used for such errors, so that an error message is printed only once in

a given interval, saying that this particular error occurred a specific number of times during that interval.

(Bug #17986385)

• Replication: SHOW SLAVE STATUS used incorrect values when reporting MASTER_SSL_CRL and

MASTER_SSL_CRLPATH. (Bug #17772911, Bug #70866)

References: This issue is a regression of: Bug #11747191.

• Replication: Binary log events could be sent to slaves before they were flushed to disk on the master,

even when sync_binlog was set to 1. This could lead to either of those of the following two issues

when the master was restarted following a crash of the operating system:

• Replication cannot continue because one or more slaves are requesting replicate events that do not

exist on the master.

• Data exists on one or more slaves, but not on the master.

Such problems are expected on less durable settings (sync_binlog not equal to 1), but it should

not happen when sync_binlog is 1. To fix this issue, a lock (LOCK_log) is now held during

synchronization, and is released only after the binary events are actually written to disk. (Bug

#17632285, Bug #70669)

MySQL 5.6 Release Notes

• Replication: When running the slave with slave_parallel_workers at 1 or greater, setting --

slave-skip-errors=all caused the error log to be filled with instances of the warning Slave SQL:

Could not execute Query event. Detailed error: ;, Error_code: 0. (Bug #17581990,

Bug #68429)

References: See also: Bug #17986385.

• Replication: A number of possible state messages used as values for the PROCESSLIST_STATE

column of the threads Performance Schema table were longer than the width of the column (64

characters).

The long state messages are now silently truncated in order to avoid errors. This fix applies in MySQL

5.6 only; a permanent fix for the issue is made in MySQL 5.7 and later. (Bug #17319380)

• Replication: The server did not handle correctly the insertion of a row larger than 4 GB when using row-

based replication. (Bug #17081415)

• Replication: When using row-based replication, an additional auto-increment column on the slave

version of a table was not updated correctly; a zero was inserted instead. (Bug #17066269, Bug #69680)

• Replication: Statements involving the Performance Schema tables should not be written to the binary

log, because the content of these tables is applicable only to a given MySQL Server instance, and may

differ greatly between different servers in a replication topology. The database administrator should be

able to configure (INSERT, UPDATE, or DELETE) or flush (TRUNCATE TABLE) performance schema

tables on a single server without affecting others. However, when replicating from a MySQL 5.5 master

to a MySQL 5.5 or later slave, warnings about unsafe statements updating Performance Schema

tables were elevated to errors. For MySQL 5.6 and later slaves, this prevented the simultaneous use of

performance_schema and GTIDs (see Replication with Global Transaction Identifiers).

This fix causes all updates on tables in the performance_schema database to be filtered on the

master and not replicated, regardless of the type of logging that is in effect. Prior to this fix, statements

using were handled by being marked as unsafe for replication, which caused warnings during execution;

the statements were nonetheless written to the binary log, regardless of the logging format in effect.

Existing replication behavior for tables in the INFORMATION_SCHEMA database is not changed by this

fix.

For more information, see MySQL Performance Schema. (Bug #16814264)

References: See also: Bug #14741537, Bug #18259193.

• Replication: Modifying large amounts of data within a transaction can cause the creation of temporary

files. Such files are created when the size of the data modified exceeds the size of the binary log cache

(max_binlog_cache_size). Previously, such files persisted until the client connection was closed,

which could allow them to grow until they exhausted all available disk space in tmpdir. To prevent this

from occurring, the size of a temporary file created in this way in a given transaction is now reset to 0

when the transaction is committed or rolled back. (Bug #15909788, Bug #18021493, Bug #66237)

• Replication: The server checks to determine whether semisynchronous replication has been enabled

without a lock, and if this is the case, it takes the lock and checks again. If semisynchronous replication

was disabled after the first but prior to the second one, this could cause the server to fail. (Bug

#14511533, Bug #66411)

References: See also: Bug #17920923.

• Replication: Semisynchronous replication became very slow if there were many dump threads (such

as from mysqlbinlog or slave I/O connections) working at the same time. It was also found that

MySQL 5.6 Release Notes

semisynchronous master plugin functions were called even when the dump connections did not support

semisynchronous replication, which led to locking of the plugin lock as well as wasting time on necessary

code.

After this fix, non-semisynchronous dump threads no longer call semisynchronous master functions to

observe binary events. (Bug #70218, Bug #17434690)

• Microsoft Windows: On Microsoft Windows, the rw-lock backup implementation for the my_atomic_*

functions was always used. Now, the native Microsoft Windows implementation is used, where available.

(Bug #18054042)

• mysql_install_db could hang while reading /dev/random to generate a random root password.

(Bug #18395378)

• While printing the server version, the mysql client did not check for buffer overflow in a string variable.

(Bug #18186103)

• Compilation failed if MySQL was configured with CFLAGS set to include a -Werror option with an

argument. (Bug #18173037)

• A shared libmysqld embedded server library was not built on Linux. A new

WITH_EMBEDDED_SHARED_LIBRARY CMake option now makes this possible. (Bug #18123048, Bug

#16430656, Bug #68559)

• Building MySQL from source on Windows using Visual Studio 2008 failed with an identifier not

found error due to a regression introduced by the patch for Bug#16249481. (Bug #18057449)

References: This issue is a regression of: Bug #16249481.

• When tables are reopened from the table cache and the current thread is not instrumented for the

Performance Schema, a table handle was unnecessarily instrumented. (Bug #18047865)

• The SUM_SORT_MERGE_PASSES column value in the events_statements_summary_by_digest

Performance Schema table was calculated incorrectly. (Bug #17938255)

• If the events_statements_summary_by_digest Performance Schema table was full when a

statement with a new digest was found, the Performance_schema_digest_lost status variable was

not incremented. (Bug #17935314)

• The audit log plugin could cause a server exit during log file rotation operations when there were many

operations happening for multiple connections. (Bug #17930339)

• The optimizer could push down a condition when the index did not have the key part present in the

condition. (Bug #17814492)

• Contraction information in a collation could be mishandled, resulting in incorrect decisions about whether

a character is part of a contraction, and miscalculation of contraction weights. (Bug #17760379)

• DROP TRIGGER succeeded even with the read_only system variable enabled. (Bug #17503460)

• If used to process a prepared CALL statement for a stored procedure with OUT or INOUT parameters,

mysql_stmt_store_result() did not properly set the flags required to retrieve all the result sets.

(Bug #14492429, Bug #17849978)

• Aggregating the results of a subquery in the FROM clause could produce incorrect results. (Bug #71244,

Bug #18014565)

• A query that creates a temporary table to find distinct values and has a constant value in the projected

list could produce incorrect results. (Bug #70657, Bug #17634335)

MySQL 5.6 Release Notes

• When run by root, mysqld --help --verbose exited with a nonzero error code after displaying the

help message. (Bug #70058, Bug #17324415)

• A deadlock error occurring during subquery execution could cause an assertion to be raised. (Bug

#69969, Bug #17307201)

• A temporal literal string without delimiters and more than 14 digits was validated as a TIMESTAMP/

DATETIME value with a two-digit precision fractional seconds part. But fractional seconds should always

be separated from other parts of a time by a decimal point. (Bug #69714, Bug #17080703)

• For system variables that take a string value, SET statements permitted an unquoted value, but values

that contained dots were parsed incorrectly and only part of the value was assigned. For example, SET

GLOBAL slow_query_log_file = my_slow.log assigned the value my_slow. Now such values

must be quoted or an error occurs. (Bug #69703, Bug #17075846)

• The mysqladmin, mysqlbinlog, mysqlcheck, mysqldump, mysqlimport, mysqlslap, and

mysqlshow programs now support a --secure-auth option that prevents sending passwords to the

server in old (pre-4.1) format. This option is enabled by default; use --skip-secure-auth to disable

it. (Bug #69051, Bug #16723046)

• MySQL client programs from a Community Edition distribution could not connect using SSL to a MySQL

server from an Enterprise Edition. This was due to a difference in certificate handling by yaSSL and

OpenSSL (used for Community and Enterprise, respectively). OpenSSL expected a blank certificate

to be sent when not all of the --ssl-ca, --ssl-cert, and --ssl-key options were specified, and

yaSSL did not do so. To resolve this, yaSSL has been modified to send a blank certificate when an

option is missing. (Bug #68788, Bug #16715064)

• Messages written by the server to the error log for LDML collation definition problems were missing the

collation name. (Bug #68144, Bug #16204175)

• On Windows, mysql_install_db.pl could be run only from within the bin directory under the

installation directory. (Bug #42421, Bug #11751526)

Changes in MySQL 5.6.16 (2014-01-31, General Availability)

Known limitations of this release:

Note

Building MySQL from source on Windows using Visual Studio 2008

fails with an identifier not found error. Later versions of Visual

Studio are unaffected. The workaround is to set the CMake build option

INNODB_PAGE_ATOMIC_REF_COUNT to OFF. This option is ON by default.

Note

If you have InnoDB tables with full-text search indexes and you are upgrading from

MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server

will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.

As a workaround, remove full-text search indexes prior to upgrading and rebuild full-

text search indexes after the upgrade is completed.

• Functionality Added or Changed

• Bugs Fixed

MySQL 5.6 Release Notes

Functionality Added or Changed

• InnoDB: New global configuration parameters, innodb_status_output and

innodb_status_output_locks, allow you to dynamically enable and disable the standard InnoDB

Monitor and InnoDB Lock Monitor for periodic output. Enabling and disabling monitors for periodic

output by creating and dropping specially named tables is deprecated and may be removed in a future

release. For additional information, see InnoDB Monitors. (WL #7377)

• Previously, ALTER TABLE in MySQL 5.6 could alter a table such that the result had temporal columns

in both 5.5 and 5.6 format. Now ALTER TABLE upgrades old temporal columns to 5.6 format for ADD

COLUMN, CHANGE COLUMN, MODIFY COLUMN, ADD INDEX, and FORCE operations. This conversion

cannot be done using the INPLACE algorithm because the table must be rebuilt, so specifying

ALGORITHM=INPLACE in these cases results in an error. Specify ALGORITHM=COPY if necessary.

When ALTER TABLE does produce a temporal-format conversion, it generates a message that can be

displayed with SHOW WARNINGS: TIME/TIMESTAMP/DATETIME columns of old format have

been upgraded to the new format. (Bug #17246318)

• CMake now supports a -DTMPDIR=dir_name option to specify the default tmpdir value. If unspecified,

the value defaults to P_tmpdir in <stdio.h>. Thanks to Honza Horak for the patch. (Bug #68338, Bug

#16316074)

Bugs Fixed

• InnoDB; Replication: Attempting to reset a replication slave while innodb_force_recovery

is greater than 0 would return a cryptic error message: ERROR(1030) HY000: Got error

-1 from storage engine. The error message has been changed to: ERROR HY000:

Operation not allowed when innodb_force_recovery > 0. Replication options such as

relay_log_info_repository=TABLE and master_info_repository=TABLE store information

in tables in InnoDB. When innodb_force_recovery is greater than 0, replication tables cannot be

updated which may cause replication administration commands to fail. (Bug #17287443, Bug #69907)

• InnoDB; Replication: Using the InnoDB memcached plugin (see InnoDB memcached Plugin) with

innodb_api_enable_binlog set to 1 caused the server to leak memory. (Bug #70757, Bug

#17675622)

• InnoDB: A boolean mode full-text search query would result in a memory access violation during

parsing. (Bug #17978763)

• InnoDB: When new indexes are added by an ALTER TABLE operation, instead of only saving table-

level statistics and statistics for the new indexes, InnoDB would save statistics for the entire table,

including the table's other indexes. This behavior slowed ALTER TABLE performance. (Bug #17848838,

Bug #16511145)

• InnoDB: Due to a parser error, full-text search queries that include a sub-expression could return the

wrong result. (Bug #17840768)

• InnoDB: The innochecksum tool did not use a Windows-specific API to retrieve file size information,

which resulted in an incorrect error message (Error: ibdata1 cannot be found) when the

MySQL 5.6 innochecksum 2GB file size limit was exceeded. innochecksum now provides support for

files larger than 2GB in both MySQL 5.6 and MySQL 5.7. (Bug #17810862, Bug #70936)

• InnoDB: Due to a regression introduced by the fix for Bug#17371537, memory was not allocated for the

default memcached engine when using the default memcached engine as the backstore for data instead

of InnoDB. (Bug #17800829)

MySQL 5.6 Release Notes

• InnoDB: InnoDB would report an incorrect operating system error code after failing to initialize. (Bug

#17788055, Bug #70867)

• InnoDB: Manipulating a table after discarding its tablespace using ALTER TABLE ... DISCARD

TABLESPACE could result in a serious error. (Bug #17700280)

• InnoDB: Persistent optimizer statistics would cause stalls due to latch contention. (Bug #17699331, Bug

#70768)

• InnoDB: An InnoDB full-text search failure would occur due to an “unended” token. The string and string

length should be passed for string comparison. (Bug #17659310)

• InnoDB: MATCH() AGAINST() queries that use a long string as an argument for AGAINST() could

result in an error when run on an InnoDB table with a full-text search index. (Bug #17640261)

• InnoDB: In debug builds, a merge insert buffer during a page read would cause a memory access

violation. (Bug #17561188)

• InnoDB: In sync0rw.ic, rw_lock_x_lock_func_nowait would needlessly call

os_thread_get_curr_id. (Bug #17509710, Bug #70417)

• InnoDB: Truncating a memcached InnoDB table while memcached is performing DML operations would

result in a serious error. (Bug #17468031)

• InnoDB: The server could fail to restart if a crash occurred immediately following a RENAME TABLE in

an ALTER TABLE, RENAME TABLE sequence. (Bug #17463290)

• InnoDB: If a tablespace data file path is updated in a .isl file and then a crash recovery is performed,

the updated tablespace data file path is read from the .isl file but the SYS_DATAFILES table would

not be not updated. The SYS_DATAFILES table is now updated with the new data file path after crash

recovery. (Bug #17448389)

• InnoDB: Attempting to rename a table to a missing database would result in a serious error. (Bug

#17447500)

• InnoDB: If the first page (page 0) of file-per-table tablespace data file was corrupt, recovery would be

halted even though the doublewrite buffer contained a clean copy of the page. (Bug #17335427, Bug

#70087, Bug #17341780)

• InnoDB: The InnoDB memcached Readme file (README-innodb_memcached) incorrectly stated that

libevent 1.6.0 is linked statically into daemon memcached. The bundled version of libevent is 1.4.12, not

1.6.0. (Bug #17324419, Bug #70034)

• InnoDB: The ALTER TABLE INPLACE algorithm failed to decrease the auto-increment value. (Bug

#17250787, Bug #69882)

• InnoDB: Comments in btr0cur.cc incorrectly stated that btr_cur_pessimistic_update() and

btr_cur_optimistic_update() would accept a NULL value. (Bug #17231743, Bug #69847)

• InnoDB: dict_table_schema_check would call dtype_sql_name needlessly. (Bug #17193801,

Bug #69802)

• InnoDB: The function os_file_get_status would not work with raw devices. (Bug #17023438, Bug

#69424)

• InnoDB: During crash recovery, an incorrect transaction active time would result in rolling back an

uncommitted transaction. (Bug #16936961, Bug #69438)

MySQL 5.6 Release Notes

• InnoDB: Heap block debugging information (file_name, lineno), used for logging diagnostics, would

appear in release builds. This information should only appear in debug builds. (Bug #16924719, Bug

#69422)

• InnoDB: An online ALTER TABLE operation would consume more memory than expected. During an

online ALTER TABLE operation, an online log buffer containing a head and tail buffer is created for each

index that is created or rebuilt. The tail buffer is the writer context and is only required for concurrent

write operations on an index while the ALTER TABLE operation is in progress. The head buffer is the

reader context and is only required during the log apply phase. To reduce memory consumption, the

tail buffer is now allocated when the first DML statement is run on the index, and the head buffer is only

allocated in the log apply phase and freed afterwards. (Bug #16868967, Bug #69325, Bug #17911720)

• InnoDB: Renaming a column while also adding or dropping columns in the same ALTER TABLE

operation would cause an error. (Bug #16864981)

• InnoDB: On Windows, the full-text search (FTS) object ID was not in the expected hexadecimal format.

(Bug #16559254)

References: See also: Bug #16559119.

• InnoDB: Fetching and releasing pages from the buffer pool and tracking the page state are expensive

and complex operations. Prior to the bug fix, these operations were performed using a page mutex.

Using a page mutex to track several things is expensive and does not scale well. The bug fix separates

fetch and release tracking (in-use state) of a page from page I/O state tracking. Fetch and release is now

tracked using atomics where available.

For portability, a new CMake build option, INNODB_PAGE_ATOMIC_REF_COUNT (default ON), can be

used to disable atomic page reference counting on platforms where atomics support is not available.

When atomic page reference counting is enabled (default), “[Note] InnoDB: Using atomics

to ref count buffer pool pages” is printed to the error log at server startup. If atomic page

reference counting is disabled, “[Note] InnoDB: Using mutexes to ref count buffer pool

pages” is printed instead. (Bug #16249481, Bug #68079)

• InnoDB: Table renaming errors would appear in the LATEST FOREIGN KEY ERROR section of the

SHOW ENGINE INNODB STATUS output. (Bug #12762390, Bug #61746)

• InnoDB: UNIV_SYNC_DEBUG, which was disabled in univ.i with the fix for Bug#16720368, is now

enabled. (Bug #69617, Bug #17033591)

• Partitioning: Queries using the index_merge optimization (see Index Merge Optimization) could return

invalid results when run against tables that were partitioned by HASH. (Bug #17588348, Bug #70588)

References: See also: Bug #16862316, Bug #17648468, Bug #18167648.

• Partitioning: When no partition had returned a row since the last HA_ERR_KEY_NOT_FOUND error, the

use of uninitialized memory in the priority queue used for returning rows in sorted order could lead to a

crash of the server. (Bug #17401628)

• Replication: When the binary log I/O cache grew to exactly 32768 bytes and the current transaction was

preceded by a transaction whose size was greater than 32768 bytes, events could be corrupted when

written into the binary log. (Bug #17842137)

• Replication: Creating and dropping large numbers of temporary tables could lead to increased memory

consumption. (Bug #17806014)

• Replication: When log_warnings is greater than 1, the master prints binary log dump thread

information—containing the slave server ID, binary log file name, and binary log position—in

MySQL 5.6 Release Notes

mysqld.1.err. A slave server ID greater than 2 billion was printed with a negative value in such cases.

(Bug #17641586, Bug #70685)

• Replication: mysqlbinlog --verbose failed when it encountered a corrupt row event in the binary

log. Such a row event could also cause the slave to fail. (Bug #17632978)

References: See also: Bug #16960133.

• Replication: mysqlbinlog did not properly decode DECIMAL values in a row-based binary log. This

could cause invalid values to be printed out for DECIMAL columns. (Bug #17544169)

References: See also: Bug #14309019.

• Replication: Seconds_Behind_Master in the output of SHOW SLAVE STATUS could under some

conditions be reported as 0 when it should have had a value greater than zero. (Bug #17233214)

References: See also: Bug #16579028.

• Replication: Invalid event offsets in the binary log were not always handled correctly, which could lead

to replication failure. (Bug #16736412, Bug #69087)

• Replication: The semisynchronous replication plugin was called twice for a DDL statement,

incrementing Rpl_semi_sync_master_yes_tx by 2 instead of 1 each time such a statement was

executed. (Bug #70410, Bug #17509011)

• Microsoft Windows: On Windows, the --local-service server option did not work, and was not

displayed in the --help message. (Bug #69637, Bug #17049656)

• FORCE INDEX [FOR ORDER BY] (index_name) did not work for joins.

The fix for this bug also changes the warning created for EXPLAIN. Instead of printing only {IGNORE|

USE|FORCE} INDEX it now also prints FOR {GROUP BY|ORDER BY|JOIN} if that was specified in the

query. (Bug #17889511)

• With the compressed client/server protocol enabled, Performance Schema statement instrumentation

could raise an assertion. (Bug #17794846)

• An assertion could be raised if a filesort failed to resize its main buffer when record properties

changed. (Bug #17757914)

• In some cases, UNIX_TIMESTAMP() could return NULL when it should return 0. (Bug #17728371)

• The cache used for the Index Merge access method was freed only after successful retrieval of all rows.

Interruption or failure of the operation led to a file descriptor leak. (Bug #17708621)

• Using the mysqldump --set-gtid-purged option with no value caused mysqldump to crash. (Bug

#17650245)

• A race condition between Performance Schema statement event threads led to a server exit. (Bug

#17637970)

• In a view definition requireing resolution of aggregrate expressions within a subquery to an outer query,

selecting from the view could cause a server exit. (Bug #17547804)

References: This issue is a regression of: Bug #16436383.

• An addressing error in accessing the join buffer could produce invalid results or a server exit. (Bug

#17513341)

MySQL 5.6 Release Notes

• mysql_config incorrectly included some flags to generate compiler warning output. (Bug #17400967)

• With semijoin optimization enabled, queries with nested subqueries could cause a server exit due to

incorrect resolution of references to columns in the middle query block. (Bug #17398972)

• In some cases, the optimizer wrote fixed-length temporary MyISAM tables to disk rather than variable-

length temporary tables. (Bug #17231940)

• Enabling the validate_password plugin could result in incorrect password hashes being stored in the

mysql.user table. (Bug #17065383)

• For accounts authenticated using the sha256_password plugin, setting the password after the

password had been expired did not clear the password-expired flag. (Bug #16872181)

• On OS X 10.7, a race condition involving vio_shutdown() and the select-based implementation of

vio_io_wait() could cause a server exit. (Bug #16354789, Bug #17733393)

• Host names in example URLs used within the source code were replaced by names in the example.com

domain, the domain intended by IANA for this purpose. (Bug #15890092)

• For utf8 and utf8mb4 strings, handler functions unnecessarily called a Unicode conversion function.

(Bug #14057034)

• Several -W warning flags were turned off for compilation in maintainer mode if MySQL was configured

with -DWITH_INNODB_MEMCACHED=1. (Bug #13898319)

• Calling the ExtractValue() function with an invalid XPath expression could in some cases lead to a

failure of the server. (Bug #12428404, Bug #61065)

• Use of a nonmultibyte algorithm for skipping leading spaces in multibyte strings could cause a server

exit. (Bug #12368495, Bug #18315770)

• With ONLY_FULL_GROUP_BY SQL mode enabled, a query that uses GROUP BY on a column derived

from a subquery in the FROM clause failed with a column isn't in GROUP BY error, if the query was

in a view. (Bug #11923239)

• mysqldump --single-transaction acquired metadata locks for each dumped table but did not

release them until the dump operation finished. Consequently, other DDL operations on a dumped table

blocked even after the table itself had been dumped. mysqldump now attempts to release metadata

locks earlier. (Bug #71017, Bug #17862905)

• sql_resolver.cc referred to partitioning code that should have been protected by an #ifdef, even

when MySQL was configured with -DWITH_PARTITION_STORAGE_ENGINE=OFF. (Bug #71010, Bug

#17876794)

• Several issues identified by the Coverity static analysis tool were fixed. Thanks to Honza Horak for the

patch. (Bug #70830, Bug #17760511)

• The prototype of the Performance Schema instrumentation API mysql_cond_timedwait() call was

fixed to be drop-in compatible with pthread_cond_timedwait(). This fix affects only implementors of

third-party plugins. (Bug #70628, Bug #17702677)

• An incorrect result could be returned for a query with an IF() predicate in the WHERE clause combined

with OUTER JOIN in a subquery that is transformed to a semijoin. (A workaround is to disable semijoin

using SET optimizer_switch='semijoin=off';) (Bug #70608, Bug #17600176)

• Complex updates of Performance Schema tables involving joins or subqueries failed to update every

row. (Bug #70025, Bug #17309657)

MySQL 5.6 Release Notes

• Some files in the file_instances Performance Schema table were not being removed because the

file-removal operation was not instrumented. (Bug #69782, Bug #17209750)

• For the path specified with the --basedir option, mysql_plugin attempted to unlink the path rather

than free the memory in which the path was stored. (Bug #69752, Bug #17168602)

• It was not possible to query a view with an ORDER BY clause that referenced an alias in the SELECT

clause of the view definition, unless all columns in the view were named in the select list.

To handle this problem, the server now writes a view differently into the .frm file that stores the view

definition. If you experience view-evaluation errors such as just described, drop and recreate the view so

that the .frm file contains the updated view representation. (Bug #69678, Bug #17077305)

• For the utf8_bin collation, ORDER BY LOWER(col_name) could produce incorrect ordering. (Bug

#69005, Bug #16691598)

• A full-text search combined with derived tables (subqueries in the FROM clause) caused a server exit.

Now if a full-text operation depends on a derived table, the server produces an error indicating that a full-

text search cannot be done on a materialized table. (Bug #68751, Bug #16539903)

• COUNT(DISTINCT) sometimes produced an incorrect result when the last read row contained a NULL

value. (Bug #68749, Bug #16539979, Bug #71028, Bug #17867117)

• Some scripts displayed out-of-date information regarding where to report bugs. (Bug #68742, Bug

#16530527)

• Updating a FEDERATED table with UPDATE... JOIN caused a server exit when the local table

contained a single row and that row could be joined to a row in the FEDERATED table. (Bug #68354, Bug

#16324629)

• The make_atomic_cas_body64 implementation on IA32 with gcc but without gcc builtins could be

miscompiled due to an incorrect constraint. The patch also causes MySQL to use builtin atomics when

compiled using Clang. (Bug #63451, Bug #17242996)

• mysql_install_db referred to the obsolete mysqlbug script for reporting problems. It now refers to

http://bugs.mysql.com/ instead. (Bug #29716, Bug #11746921)

Changes in MySQL 5.6.15 (2013-12-03, General Availability)

A known limitation of this release:

Note

If you have InnoDB tables with full-text search indexes and you are upgrading from

MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server

will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.

As a workaround, remove full-text search indexes prior to upgrading and rebuild full-

text search indexes after the upgrade is completed.

• Packaging Notes

• Functionality Added or Changed

• Bugs Fixed

MySQL 5.6 Release Notes

Packaging Notes

• Previously, MySQL Server distributions included the MySQL Reference Manual in Info format (the Docs/

mysql.info file). Because the license for the manual restricts redistribution, its inclusion in Community

packages caused problems for downstream redistributors, such as those who create Linux distributions.

Community distributions of MySQL Server no longer include the mysql.info file, to make the repackaging

and redistribution process easier (for example, the source tarball and its checksum can be used directly).

This change applies to all source and binary Community packaging formats. Commercial (Enterprise)

distributions are unchanged.

For those who wish to continue using the MySQL Reference Manual in Info format, we have made it

available at https://dev.mysql.com/doc/.

Functionality Added or Changed

• Incompatible Change: Several statement instruments in the setup_instruments table are used by

the Performance Schema during the early stages of statement classification before the exact statement

type is known. These instruments were renamed to more clearly reflect their “abstract” nature:

Old Instrument Name New Instrument Name

statement/com/ statement/abstract/new_packet

statement/com/Query statement/abstract/Query

statement/rpl/relay_log statement/abstract/relay_log

In addition, statistics for abstract instruments are no longer collected in the following tables, because no

such instrument is ever used as the final classification for a statement:

events_statements_summary_by_thread_by_event_name

events_statements_summary_by_account_by_event_name

events_statements_summary_by_user_by_event_name

events_statements_summary_by_host_by_event_name

events_statements_summary_global_by_event_name

Applications that refer to the old instrument names must be updated with the new names. For more

information about the use of abstract instruments in statement classification, see Performance Schema

Statement Event Tables. (Bug #16750433, Bug #17271055)

• The Performance Schema now instruments the read/write lock Delegate::lock, which is used for the

following classes:

Trans_delegate

Binlog_storage_delegate

Binlog_transmit_delegate

Binlog_relay_IO_delegate

A different instrument name is used for each subclass, to have distinct statistics for distinct uses. The

instruments are visible in the schema.setup_instruments table and have these names:

wait/synch/rwlock/sql/Trans_delegate::lock

wait/synch/rwlock/sql/Binlog_storage_delegate::lock

wait/synch/rwlock/sql/Binlog_transmit_delegate::lock

wait/synch/rwlock/sql/Binlog_relay_IO_delegate::lock

(Bug #17590161, Bug #70577)

• A new CMake option, WITH_ASAN, permits enabling AddressSanitizer for compilers that support it. (Bug

#17435338)

MySQL 5.6 Release Notes

• The hash function used for metadata locking was modified to reduce overhead. (Bug #68487, Bug

#16396598)

Bugs Fixed

• InnoDB; Replication: The InnoDB mecached plugin would update a record before inserting to the

binary log, which would cause slave server replication to stop. The insert should occur before the

update. (Bug #17358875)

• InnoDB: A regression introduced by the fix for Bug#17371537 resulted a memory leak for memcached

insert operations. (Bug #17738935)

References: See also: Bug #17371537.

• InnoDB: Fault-tolerant code found in the log apply code for InnoDB ALTER TABLE ... IN PLACE

could result in data corruption. (Bug #17625063, Bug #17512497)

• InnoDB: The trx->error_key_num field was not initialized in the error injection code found in

storage/innobase/handler/handler0alter.cc. The error_key_num field is usually 0 but can

be a non zero value if the memory buffer of a DDL transaction object is reused. (Bug #17624926)

• InnoDB: Databases names beginning with a digit would cause a full-text search (FTS) parser error. (Bug

#17607956)

References: See also: Bug #17161372.

• InnoDB: An ALTER TABLE ... CHANGE [COLUMN] operation would result in an

rbt_empty(index_cache->words) assertion. (Bug #17536995)

• InnoDB: CHECK TABLE would ignore the QUICK option. (Bug #17513737)

• InnoDB: An excessive amount of memory would be consumed when querying

INFORMATION_SCHEMA.INNODB_FT_INDEX_TABLE. The problem would occur for very large full-text

search indexes. (Bug #17483582, Bug #70329)

• InnoDB: Running SHOW ENGINE INNODB STATUS on one connection thread and killing that thread

by running a KILL CONNECTION statement from a different connection thread would result in a severe

error. (Bug #17474166)

• InnoDB: In debug builds, test case failures would occur due to ibuf_contract_ext performing

merges and dict_stats_update returning evicted pages back into the buffer pool while

ibuf_change_buffering_debug is enabled. (Bug #17446090)

• InnoDB: Setting the O_DIRECT flag on a file on tmpfs on some operating systems would result in an

error printed to the error log. Creating multiple temporary tables on tmpfs would cause the error to be

printed repeatedly. The error message has been changed to a warning that is only printed once when

running CREATE TABLE multiple times. (Bug #17441867)

• InnoDB: InnoDB failed to return an error when attempting to run a query after discarding the

tablespace. (Bug #17431533)

• InnoDB: A severe error would occur after discarding a tablespace. (Bug #17430207)

• InnoDB: The information_schema.innodb_metrics index_merge counter was not incremented

in btr0btr.cc. This patch also introduces new counters (index_page_reorg_attempts,

index_page_reorg_successful and index_page_discards) and renames the

index_merges counter to index_page_merge_attempts to distinguish it from the

index_page_merge_successful counter. (Bug #17409657, Bug #70241)

100

MySQL 5.6 Release Notes

• InnoDB: During a TRUNCATE TABLE operation, InnoDB: Trying to TRUNCATE a missing

index of table ... warnings would be printed to the error log. These warnings should not be

printed when the index is a full-text search (FTS) index. (Bug #17402002, Bug #70226)

References: See also: Bug #12429565.

• InnoDB: During parallel full-text search (FTS) index creation, a scanner thread reads in documents

and passes them to the tokenizer. The tokenizer frees documents from memory when tokenization is

complete. When tokenizing documents with a large amount of text, the tokenizer thread would not keep

pace with the scanner thread. As a result, memory would not be freed fast enough and the “tokenization

pending list” would grow in size. (Bug #17384979)

• InnoDB: trx_create and trx_free would be called for every memcached get request. (Bug

#17371537, Bug #70172)

• InnoDB: A full-text search (FTS) BOOLEAN MODE query with an invalid character in the query string

could result in a memory access violation failure. (Bug #17350055)

• InnoDB: Full-text index creation on a large table failed due to insufficient temporary table space and

result in a misleading “incorrect key file” error. (Bug #17339606)

• InnoDB: In btr_validate_level there are checks to ensure that all B-tree pages are marked when

allocated. The checks failed on the change buffer because the allocation of change buffer pages is

handled differently than other B-tree pages. (Bug #16884217)

• InnoDB: The hardcoded size for the srv_max_n_threads variable was insufficient. The variable

setting is now configured based on the maximum number of connection threads and InnoDB

background threads. (Bug #16884077)

• InnoDB: A SELECT COUNT(*) query would take a long time to complete when run concurrently with

a LOAD DATA operation. The mtr_memo_contains function, which determines if an object is part

of a memo in a mini transaction, contained a nested loop that caused the query to run slowly. (Bug

#16764240, Bug #69141)

• InnoDB: When the change buffer is enabled, InnoDB failed to write a transaction log record when

merging a record from the insert buffer to a secondary index page if the insert was performed as an

“update-in-place”. (Bug #16752251, Bug #69122)

• InnoDB: An existing full-text index would become invalid after running ALTER TABLE ADD FULLTEXT

due to an unsynchronized full-text cache. (Bug #16662990, Bug #17373659)

• InnoDB: Due to a regression in MySQL 5.6, creating or dropping tables with

innodb_force_recovery set to 3 (SRV_FORCE_NO_TRX_UNDO) failed. Additionally, this bug fix

includes a code modification that sets InnoDB to read-only when innodb_force_recovery is set to a

value greater than 3 (SRV_FORCE_NO_TRX_UNDO). (Bug #16631778, Bug #69892)

• InnoDB: An InnoDB memcached configuration error message contained an incorrect file name.

The error message stated, Please create config table containers in database

innodb_memcache by running innodb_config.sql. error 31. The correct file name

is innodb_memcached_config.sql. Also, the “error 31” portion of the error message has been

translated to its text equivalent, which is “Table not found”. (Bug #16498810, Bug #68684)

• InnoDB: In mutex_spin_wait(), the sync_array_reserve_cell function could fail to find an

empty slot on systems with sync wait arrays that are small in size, resulting in an error. (Bug #16245498)

• InnoDB: Full-text search (FTS) index savepoint information would not be set resulting in a severe error

when attempting to rollback to the savepoint. (Bug #14639605, Bug #17456092)

101

MySQL 5.6 Release Notes

• InnoDB: When index_read_map is called for an exact search and fails to return a record due to non-

matching search criteria, the cursor would be positioned on the next record after the searched key. A

subsequent call to index_next would return the next record instead of returning the previous non-

matching row, thereby skipping a record. (Bug #14621190, Bug #15965874, Bug #17314241, Bug

#70038, Bug #17413093, Bug #12860669, Bug #60220, Bug #17565888)

• InnoDB: An implicit rollback caused the server to halt when restarting with an

innodb_force_recovery value of 3 or greater. This bug was addressed by the combination of fixes

for Bug #16310467 and Bug #17253499. (Bug #14178835)

References: See also: Bug #16310467, Bug #17253499.

• InnoDB: Converting a table with a large number of columns from MyISAM to InnoDB would cause an

assertion due to insufficient log buffer space. Instead of asserting, InnoDB now attempts to increase log

buffer size automatically if the redo log size is too large. (Bug #11758196, Bug #50366)

• Partitioning: The storage engine was set incorrectly during a rebuild of a partition; the table storage

engine was ignored and the default storage engine used instead. Thus, in MySQL 5.1, it was possible

for REBUILD PARTITION to change the partition storage engine from InnoDB to MyISAM, and for the

reverse (rebuilding partitions of MyISAM tables causing the partitions to use InnoDB) to occurin MySQL

5.5 and later. Now, when rebuilding partitions, the storage engine actually used by the table is checked

and used by the handler for the rebuild operation, so that the partition storage engine is not inadvertently

changed. (Bug #17559867)

• Partitioning: After disabling the parent table's indexes with ALTER TABLE ... DISABLE KEYS,

rebuilding any of its partitions enabled the indexes on those partitions, leading MyISAM to fail with an

error when the optimizer tried to use one of the affected indexes.

Now in such cases, we check for disabled indexes on the table before rebuilding any of its partitions.

If the indexes have been disabled, then we disable them on the partition following the rebuild. (Bug

#16051817)

• Replication: A replication master did not handle correctly the disabling of the semisync plugin on the

master and the slave, with a subsequent stopping of the slave. (Bug #17460821, Bug #70349)

• Replication: The final argument in the SET clause of a LOAD DATA ... SET statement was repeated

in the binary log. (Bug #17429677, Bug #70277)

• Replication: When an error encountered by the dump thread while reading events from the active binary

log file was a temporary error, so that the dump thread tried to read the event, it was possible for the

dump thread to seek the wrong position, which could cause one or more events to be resent. To prevent

this, the thread's position is obtained after each correct read of an event.

In addition, with this fix, only binary logs that are not closed normally are marked as possibly being

corrupted.

Finally, two warnings are added; these are now returned when a dump thread encounters a temporary

error. (Bug #17402313)

• Replication: Setting rpl_semi_sync_master_enabled while the master was waiting for a reply from

the slave could in some cases cause the master to fail. (Bug #17327454, Bug #70045)

• Replication: When stopping the I/O thread, it was possible with a very large transaction (equivalent to

a binary log size greater than 100MB) that the thread did not receive the transaction to the end. When

reconnecting with MASTER_AUTO_POSITION=1 it then tried to fetch changes from the next transaction,

which could lead to loss of the incomplete transaction and its data. (Bug #17280176, Bug #69943)

102

MySQL 5.6 Release Notes

• Replication: Trying to set CHANGE MASTER TO ... MASTER_AUTO_POSITION = 0 failed with error

1777 (ER_AUTO_POSITION_REQUIRES_GTID_MODE_ON). (Bug #17277744)

• Replication: The value of LAST_INSERT_ID() was not correctly replicated when filtering rules were

used on the slave. (Bug #17234370, Bug #69861)

• Replication: An internal function used for storing GTID values could sometimes try to handle them as

strings of the wrong length. (Bug #17032712, Bug #69618)

• Replication: During row-based replication with binlog_row_image set to MINIMAL, updating only

some columns of a table having 9 or more columns caused mysqlbinlog to fail when it was used with

the --verbose option. (Bug #16960133)

• Replication: Issuing a GRANT statement with invalid parameters caused the master to write

LOST_EVENTS events into its binary logs, causing replication to stop. Now such cases, if one or more

grants or revocations of privileges are successful, an incident is written to the log; otherwise, only a

warning is logged. (Bug #16629195, Bug #68892)

• libmysqlclient version 18 files were removed from MySQL-shared-compat RPM packages to

avoid a conflict between the MySQL-shared and MySQL-shared-compat RPM packages. (Bug

#17749617)

• Enabling Index Merge optimizer switches and setting a small sort_buffer_size value could lead to a

server exit. (Bug #17617945)

• Some license and documentation files were missing from Windows MSI packages. (Bug #17584523)

• Semijoin materialization strategy was not used for VARCHAR columns longer than 512 bytes, resulting in

use of a less-efficient strategy and worse query performance. (The limit in characters rather than bytes

depends on the column character set; 170 characters for utf8, for example.) (Bug #17566396)

• Using MySQL Installer to install MySQL on Windows, then using Uninstall a Program in the Control

Panel to uninstall MySQL, resulted in the MySQL service entry not being removed. (Bug #17550741)

• Selecting from the session_connect_attrs Performance Schema table under high load could cause

a server exit. (Bug #17542370)

• Compilation failures under Visual Studio 2012 were corrected. (Bug #17430236)

• An assertion was raised if SET PASSWORD was used for an account that has been manually deleted

from the mysql.user table but still present in memory. (Bug #17359329)

• The CLIENT_CONNECT_WITH_DB flag was improperly handled in the C client library. This could lead to

a malformed packet sent to the server. (Bug #17351732)

• The filesort implementation sometimes failed to allocate enough buffer space, leading to a server

exit. (Bug #17326567)

• The mysql_options() C API function could leak memory if called more than once with the

MYSQL_SET_CLIENT_IP option. (Bug #17297012)

• The CONV() function could call abs(INT_MIN), which is undefined, and cause a server exit. (Bug

#17296644)

• An error array in the SSL code was missing a comma, leading to implicit concatenation of adjacent

messages and a resulting off-by-one error in the relationship between error numbers and messages.

(Bug #17294150)

• GRANT without an IDENTIFIED BY clause resulted in an error even for existing users. (Bug #16938568)

103

MySQL 5.6 Release Notes

• GROUP_CONCAT() with an invalid separator could cause a server exit. (Bug #16870783)

• An internal InnoDB string routine could write past the end of a buffer. (Bug #16765410)

• For uninstall operations, the MySQL Server MSI installer failed to remove some files if the server was

running. This could lead to problems for a subsequent installation of a lower MySQL version: The

installer reported a successful operation but not some of the files from the original installation were not

replaced by their lower-versioned counterparts. (Bug #16685125)

• GIS intersection-related code was missing a return value check, leading to a loop in nondebug builds

and a raised assertion in debug builds. (Bug #16659166)

• Using the binary client/server protocol, the second execution of a prepared statement for a query with

parameters in the LIMIT clause raised an assertion. (Bug #16346241)

• For upgrades using the Windows MSI package installer, the upgrade dialog message was missing the

“from” version. (Bug #16053094)

• Very long database names in queries could cause the server to exit. (Bug #15912213, Bug #16900358)

• Standalone Windows MSI packages did not have the ALLUSERS property set. They now set

ALLUSERS=1. For earlier MSI packages in this MySQL series, a workaround is to use the following

command:

C:\> msiexec /i msi_installer_name ALLUSERS=1

(Bug #14647206)

• Recursion by functions called as arguments to XPath expressions was not handled correctly, sometimes

causing such expressions to fail. (Bug #14040071)

• Some .pdb files were missing from Windows Zip archive distributions. (Bug #13878021)

•

Several issues identified by the Coverity static analysis tool were fixed. Thanks to Jan Staněk and Honza

Horak for the patches. (Bug #70591, Bug #17590095)

• Setting host_cache_size at startup had no effect. (Bug #70552, Bug #17576516)

• MySQL did not compile on OS X 10.9 (Mavericks). (Bug #70542, Bug #17647863)

• In some cases, range conditions over indexes defined on column prefixes returned incomplete result

sets. (For example, SELECT ... WHERE 'abcdef1' < col_name AND col_name < 'abcdef9',

where the index on col_name indexed only the first 6 characters.) (Bug #70341, Bug #17458273)

• InnoDB full-text searches failed to find records within transactions that included savepoints. (Bug

#70333, Bug #17458835)

• If asked to upgrade a server that was running without InnoDB enabled, mysql_upgrade issued

complaints about InnoDB tables not existing (tables that will not exist unless InnoDB is available). (Bug

#70152, Bug #17361912)

• With the thread pool plugin enabled, the PROCESSLIST_USER and PROCESSLIST_HOST columns of the

threads Performance Schema table were always NULL for client sessions. Also, for the main thread,

those columns were not NULL but set to a user account.

Note

As part of the bug fix implementation, Performance Schema instrumentation for

the thread pool plugin was changed to use thread_pool, not sql.

104

MySQL 5.6 Release Notes

(Bug #70028, Bug #17310065, Bug #17049691)

• Performance Schema instrumentation overhead was reduced for frequent connect/disconnect

operations. (Bug #70018, Bug #17310878)

• COUNT(DISTINCT) should not count NULL values, but they were counted when the optimizer used

Loose Index Scan. (Bug #69841, Bug #17222452)

• In debug builds, static initialization code could call DBUG functions before the DBUG subsystem was

initialized. (Bug #69653, Bug #17063675)

• Some INSERT INTO ... SELECT ... FROM statements were slow unless the tmp_table_size

and max_heap_table_size system variables were set large enough to permit the temporary table

used for query processing to be stored in the MEMORY storage engine. (Bug #69368, Bug #16894092)

•

Some possible cases of memory use after being freed were fixed. Thanks to Jan Staněk for the patch.

(Bug #68918, Bug #16725945)

•

Missing va_end() calls were added to logging and UCS2 code. Thanks to Jan Staněk for the patch.

(Bug #68896, Bug #16725769)

• For queries of the form UPDATE ... WHERE unique_key ORDER BY ... LIMIT ..., incorrect

rows could be updated. Unique keys permit multiple NULL values, but the optimizer did not always

consider all of them. (Bug #68656, Bug #16482467)

• For an ALTER TABLE statement that renamed or changed the default value of a BINARY column, the

alteration was done using a table copy and not in place. (Bug #67141, Bug #14735373, Bug #69580,

Bug #17024290)

• The server uses the ethernet hardware address for UUID generation, but made assumptions about the

names of ethernet devices rather than querying the system for their names. Thanks to Honza Horak for

the patch. (Bug #63055, Bug #13548252)

• Host names in grant tables are stored in lowercase, but mysql_install_db could fail to observe

this convention, leading to accounts that could not be dropped with DROP USER. (Bug #62255, Bug

#12917164, Bug #62254, Bug #12917151)

• Killing a query that is performing a filesort operation resulted in an ER_SERVER_SHUTDOWN (Server

shutdown in progess) error. (Bug #18256, Bug #11745656)

Changes in MySQL 5.6.14 (2013-09-20, General Availability)

A known limitation of this release:

Note

If you have InnoDB tables with full-text search indexes and you are upgrading from

MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server

will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.

As a workaround, remove full-text search indexes prior to upgrading and rebuild full-

text search indexes after the upgrade is completed.

• Audit Log Notes

• Functionality Added or Changed

• Bugs Fixed

105

MySQL 5.6 Release Notes

Audit Log Notes

• MySQL 5.7 changed audit log file output to a new format that has better compatibility with Oracle Audit

Vault. This format has been backported to MySQL 5.6 and it is possible to select either the old or new

format using the new audit_log_format system variable, which has permitted values of OLD and NEW

(default OLD). For details about each format, see Audit Log File Formats.

In addition, when the audit log plugin rotates the audit log file, it uses a different file name format. For

a log file named audit.log, the plugin previously renamed the file to audit.log.TIMESTAMP. The

plugin now renames the file to audit.log.TIMESTAMP.xml to indicate that it is an XML file.

If you change the value of audit_log_format, use this procedure to avoid writing log entries in one

format to an existing log file that contains entries in a different format:

1. Stop the server.

2. Rename the current audit log file manually.

3. Restart the server with the new value of audit_log_format. The audit log plugin will create a new

log file, which will contain log entries in the selected format.

The API for writing audit plugins has also changed. The mysql_event_general structure has new

members to represent client host name and IP address, command class, and external user. For more

information, see Writing Audit Plugins. (WL #7076)

Functionality Added or Changed

• Incompatible Change: In MySQL 5.6.13, the statement/com/ abstract statement instrument in the

setup_instruments Performance Schema table was renamed to statement/com/new_packet.

That change has been reverted.

Applications that refer to the old instrument name must be updated with the new name. For more

information about the use of abstract instruments in statement classification, see Performance Schema

Statement Event Tables. (Bug #16750433, Bug #17271055)

• InnoDB: The InnoDB memcached plugin now supports inserts and reads on mapped InnoDB tables

that have an INTEGER defined as the primary key. (Bug #17315083, Bug #17203937)

Bugs Fixed

• Important Change; Replication: START SLAVE UNTIL SQL_AFTER_GTIDS did not cause the slave

to stop until the next GTID event was received following execution of the transaction having the indicated

GTID, which could cause issues in the case when the next GTID event is delayed, or does not exist.

Now the slave stops after completing the transaction with that GTID. (Bug #14767986)

• InnoDB; Partitioning: Following any query on the INFORMATION_SCHEMA.PARTITIONS

table, InnoDB index statistics as shown in the output of statements such as SELECT * FROM

INFORMATION_SCHEMA.STATISTICS were read from the last partition, instead of from the partition

containing the greatest number of rows. (Bug #11766851, Bug #60071)

References: See also: Bug #16882435, Bug #69179.

• InnoDB: When logging the delete-marking of a record during online ALTER TABLE...ADD PRIMARY

KEY, InnoDB writes the transaction ID to the log as it was before the deletion or delete-marking of the

record. When doing this, InnoDB would overwrite the DB_TRX_ID field in the original table, which could

result in locking issues. (Bug #17316731)

106

MySQL 5.6 Release Notes

• InnoDB: The row_sel_sec_rec_is_for_clust_rec function would incorrectly prepare to compare

a NULL column prefix in a secondary index with a non-NULL column in a clustered index. (Bug

#17312846)

• InnoDB: An assertion would be raised in fil_node_open_file due to a missing .ibd file. Instead of

asserting, InnoDB should return false and the caller of fil_node_open_file should handle the return

message. (Bug #17305626, Bug #70007)

• InnoDB: An incorrect purge would occur when rolling back an update to a delete-marked record. (Bug

#17302896)

• InnoDB: The assertion ut_ad(oldest_lsn <= cur_lsn) in file buf0flu.cc failed because the

current max LSN would be retrieved from the buffer pool before the oldest LSN. (Bug #17252421)

• InnoDB: InnoDB memcached add and set operations would perform more slowly than SQL INSERT

operations. (Bug #17214191)

• InnoDB: As commented in log0log.h, old_lsn and old_buf_free should only be compiled when

UNIV_LOG_DEBUG is enabled. (Bug #17160270, Bug #69724)

• InnoDB: Adding a foreign key with a constraint name that included the string “_ibfk_” caused InnoDB

to create a duplicate constraint with a generated internal name. The generated internal name could also

collide with an existing user-defined constraint of the same name, causing a duplicate key error. (Bug

#17076737, Bug #69693, Bug #17076718, Bug #69707)

• InnoDB: The ha_innobase::clone function would incorrectly assert that a thread cannot clone a

table handler that is used by another thread, and that the original table handler and the cloned table

handler must belong to the same transaction. The incorrect assertions have been removed. (Bug

#17001980)

• InnoDB: A regression introduced in the fix for Bug #14606334 would cause crashes on startup during

crash recovery. (Bug #16996584)

• InnoDB: Rolling back an INSERT after a failed BLOB write would result in an assertion failure. The

assertion has been modified to allow NULL BLOB pointers if an error occurs during a BLOB write. (Bug

#16971045)

• InnoDB: When dropping all indexes on a column with multiple indexes, InnoDB failed to block a DROP

INDEX operation when a foreign key constraint requires an index. (Bug #16896810)

• InnoDB: An assertion failure would occur in file row0log.cc on ROW_FORMAT=REDUNDANT tables that

contained an unexpected but valid data directory flag. (Bug #16863098)

• InnoDB: A regression introduced with the fix for Bug #11762038 would cause InnoDB to raise an

incorrect error message. The message stated that, “InnoDB cannot delete/update rows with cascading

foreign key constraints that exceed max depth of 20”. The error message would occur when killing

connections reading from InnoDB tables that did not have foreign key constraints. (Bug #16710923)

References: This issue is a regression of: Bug #11762038.

• InnoDB: In debug builds, an assertion failure would occur if innodb_log_group_home_dir

does not exist. Instead of an assertion, InnoDB now aborts with an error message if

innodb_log_group_home_dir does not exist. (Bug #16691130, Bug #69000)

• InnoDB: For the Barracuda file format and beyond, the externally stored prefix would be read even

though the prefix is already stored locally in memory. (Bug #16569640)

• InnoDB: When changing the shared tablespace file name using innodb_data_file_path and

leaving the current log files in place, InnoDB would create a new tablespace file and overwrite the

107

MySQL 5.6 Release Notes

log files resulting in a mismatch between the data dictionary and tables on disk. This bug fix ensures

that InnoDB does not create a new tablespace if there are inconsistent system tablespaces, undo

tablespaces, or redo log files. (Bug #16418661)

• InnoDB: Persistent statistics would be disabled unnecessarily when running in read-only mode. When

running in read-only mode, fetching statistics from disk does not involve any modification of on-disk data

except for when ANALYZE TABLE is run. This fix enables persistent statistics for read-only mode. (Bug

#16083211)

• InnoDB: The documentation incorrectly stated that START TRANSACTION WITH CONSISTENT

SNAPSHOT provides a consistent snapshot only if the current isolation level is REPEATABLE READ or

SERIALIZABLE. START TRANSACTION WITH CONSISTENT SNAPSHOT only works with REPEATABLE

READ. All other isolation levels are ignored. The documentation has been revised and a warning is now

generated whenever the WITH CONSISTENT SNAPSHOT clause is ignored. (Bug #14017206, Bug

#65146)

• InnoDB: The srv_master_thread background thread, which monitors server activity and performs

activities such as page flushing when the server is inactive or in a shutdown state, runs on a one second

delay loop. srv_master_thread failed to check if the server is in a shutdown state before sleeping.

(Bug #13417564, Bug #63276)

• InnoDB: An infinite loop could occur in buf_page_get_gen when handling compressed-only pages.

(Bug #12560151, Bug #61132)

• Partitioning: Creating a table t1 using CREATE TABLE ... PARTITION BY LIST ...

PARTITION ... VALUES IN (NULL), then attempting to execute CREATE TABLE ... LIKE t1

caused the server to fail. (Bug #16860588)

• Replication: The server attempted to perform an internal truncatation of the slave_worker_info

table while resetting it, even though this is a DDL operation and should not be used conccurrently with

DML operations. To prevent this from happening, the reset now performs sequential row deletion in

place of the truncation operation. (Bug #17286858, Bug #69898)

• Replication: When the --relay-log-info-file option was used together with

slave_parallel_workers set to a value greater than 1, mysqld failed to start. (Bug #17160671)

• Replication: The commit error caused by the failure of binary log rotation failure generated an incident

event in the binary log file and interrupted the user session with error messages which did not mention

that the slave server would be stopped later when the incident event was replayed.

Now, when encountering binary log rotation failure, a more helpful error message is instead written to the

log, alerting the user to investigate in a timely manner. (Bug #17016017)

• Replication: It was possible in CHANGE MASTER TO statements to set the MASTER_DELAY option

greater than the supported maximum value (2

− 1). In addition, the error resulting from setting

MASTER_DELAY to a value greater than 2

was not handled correctly. (Bug #16820156, Bug

#16960315, Bug #69249, Bug #69469)

• Replication: When a master with semisynchronous replication enabled was shut down, the master

failed to wait for either a semisyncnronous ACK or timeout before completing the shutdown. This

prevented semisynchronous replication from reverting to asynchronous replication and allowed open

transactions to complete on the master, which resulted in missing events on the slave.

To fix this problem, dump threads are now stopped last during shutdown, after the client is told to stop,

so that, if the dump thread has pending events from active clients, they can be sent to the slave. (Bug

#16775543)

108

MySQL 5.6 Release Notes

• Replication: A session attachment error during group commit causes the rollback of the transaction (as

intended), but the transaction in which this happened was still written to the binary log and replicated to

the slave. Thus, such an error could lead to a mismatched master and slave.

Now when this error occurs, an incident event is written in the binary log which causes replication

to stop, and notifies the user that redundant events may exist in the binary log. An additional error

is also now reported to the client, indicating that the ongoing transaction has been rolled back. (Bug

#16579083)

• Replication: START SLAVE failed when the server was started with

master_info_repository=TABLE and relay_log_info_repository=TABLE and with

autocommit=0, together with --skip-slave-start.

A workaround for previous versions of MySQL is to restart the slave mysqld without the --skip-

slave-start option. (Bug #16533802)

• Replication: A slave using row-based replication was unable to read the rows containing columns of

type MYSQL_TYPE_DECIMAL properly (old-style decimal, used prior to MySQL 5.0.3). Now the slave

throws an error if it receives this type of data. You can convert the old-style DECIMAL format to the

binary format used in current MySQL releases with ALTER TABLE; see Upgrading from MySQL 4.1 to

5.0, for more information. (Bug #16416302)

• Replication: DROP TEMP TABLE IF EXISTS statements could lead to failures in applying the

binary log during point-in-time recovery operations. This is due to the fact that, when using row-based

replication, the server appends IF EXISTS to any DROP TEMPORARY TABLE statements written to the

binary log, and that the slave SQL thread does not check * wildcard filter rules for DROP TEMPORARY

TABLE IF EXISTS. If --log-slave-updates was also enabled on the slave, such a statement was

preceded by a USE statement. If the database referred by the USE statement did not exist, the statement

failed, and stopped replication.

Now, when writing DROP TEMPORARY TABLE IF EXISTS into the binary log, no USE statement is

written, and the table name in the DROP TEMPORARY TABLE statement is a fully qualified table name.

(Bug #16290902)

• Savepoints could not be used successfully following an ER_LOCK_DEADLOCK error (or

ER_LOCK_WAIT_TIMEOUT error, if innodb_rollback_on_timeout was enabled). (Bug #17356954)

References: This issue is a regression of: Bug #14188793.

• The mysql_real_connect() C API function could leak memory if it failed. (Bug #17337684)

• Full-text search on InnoDB tables failed on searches that used the + boolean operator. (Bug

#17280122)

• For single-threaded workloads, the optimizer recognizes some special cases for which it can avoid

function calls and enhance performance. (Bug #17234723)

• AES_ENCRYPT() and AES_DECRYPT() failed to work correctly when MySQL was built with an

AES_KEY_LENGTH value of 192 or 256. (Bug #17170207)

• SELECT * from performance_schema.events_statements_current could raise an assertion

due to a race condition under load. (Bug #17164720)

• InnoDB full-text searches failed in databases whose names began with a digit. (Bug #17161372)

• A successful connection failed to reset the per-IP address counter used to count successive connection

failures. This could possibly cause a host to be blocked, when the max_connect_errors limit was

reached. (Bug #17156507)

109

MySQL 5.6 Release Notes

• With the thread pool plugin enabled and SSL in use, an error in one connection might affect other

connections, causing them to experience a lost connection. (Bug #17087862)

• Under load, truncating the accounts Performance Schema table could cause a server exit. (Bug

#17084615)

• Within a stored program, comparison of the value of a scalar subquery with an IN clause resulted in an

error for the first execution and raised an assertion for the second execution. (Bug #17029399)

• The my_strtoll10() function could incorrectly convert some long string-format numbers to numeric

values and fail to set the overflow flag. (Bug #16997513)

• A race condition in the thread pool plugin could cause status variables such as Aborted_connects not

to be incremented and permitting concurrent kills to happen for the same thread ID. (Bug #16959022)

• For partitioned tables, queries could return different results depending on whether Index Merge was

used. (Bug #16862316)

References: See also: Bug #17648468, Bug #176588348, Bug #18167648.

• Excessive memory consumption was observed for multiple execution of a stored procedure under these

circumstances: 1) The stored procedure had an SQL statement that failed during validation. 2) The

stored procedure had an SQL statement that required repreparation. (Bug #16857395)

• For some statements, memory leaks could result when the optimizer removed unneeded subquery

clauses. (Bug #16807641)

References: This issue is a regression of: Bug #15875919.

• Password rewriting in the general query log now also applies to prepared statements. (Bug #16732621)

• Within a stored procedure, repeated execution of a prepared CREATE TABLE statement for a table with

partitions could cause a server exit. (Bug #16614004)

• For debug builds, when the optimizer removed an Item_ref pointing to a subquery, it caused a server

exit. (Bug #16509874)

References: This issue is a regression of: Bug #16318585.

• If the primary key for the mysql.proc system table was removed (an unsupported and not-

recommended operation), the server exited for subsequent stored procedure invocation. Similar

problems could occur for other system tables. Now an error occurs instead. (Bug #16373054)

• Deadlocks involving metadata locks and InnoDB deadlocks were both reported as an

ER_LOCK_DEADLOCK error, but only InnoDB deadlocks rolled back the transaction. Now both deadlocks

roll back the transaction. (Bug #14188793)

• Metadata returned for a prepared SELECT statement that had outer joins could indicate that columns

containing NULL values were NOT NULL. (Bug #12818811)

• For queries that accessed an INFORMATION_SCHEMA table in a subquery, an attempt to lock a mutex

that had already been locked could cause a server crash. (Bug #11765744)

• Full-text search on InnoDB tables failed on searches for words containing apostrophes when using

boolean operators.

The innodb_ft_max_token_size maximum value was incorrectly defined as 252, which is the

maximum byte length. The maximum innodb_ft_max_token_size value is now 84, which is the

maximum character length. (Bug #69932, Bug #17276125)

110

MySQL 5.6 Release Notes

• InnoDB deadlock caused transaction rollback but did not release metadata locks, blocking concurrent

DDL on the transaction tables until the connection that got the deadlock issued an explicit COMMIT or

ROLLBACK. (Bug #69668, Bug #17054007)

• The libmysql.dll library was missing several symbols: my_init, mysql_client_find_plugin,

mysql_client_register_plugin, mysql_load_plugin, mysql_load_plugin_v,

mysql_options4, and mysql_plugin_options. (Bug #69204, Bug #16797982, Bug #62394)

• mysqldump wrote SET statements as SET OPTION, which failed when reloaded because the

deprecated OPTION keyword has been removed from SET syntax. (Bug #67507, Bug #15844882)

• For failure to create a new thread for the event scheduler, event execution, or new connection, no

message was written to the error log. This could lead to the impression that the event scheduler was

running normally when it was not. (Bug #67191, Bug #14749800, Bug #16865959)

• If one connection changed its default database and simultaneously another connection executed SHOW

PROCESSLIST, the second connection could access invalid memory when attempting to display the first

connection's default database. memory. (Bug #58198, Bug #11765252)

• For better robustness against stack overflow, the server now accounts for the size of the guard area

when making thread stack size requests. (Bug #35019, Bug #11748074)

Changes in MySQL 5.6.13 (2013-07-31, General Availability)

Known limitations of this release:

Note

On Microsoft Windows, MySQL Installer does not upgrade MySQL Enterprise

Backup (MEB) 3.8.1 to 3.8.2 (latest version). A workaround is to uninstall MEB 3.8.1

and then install MEB 3.8.2 (latest version) with MySQL Installer.

Note

If you have InnoDB tables with full-text search indexes and you are upgrading from

MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server

will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.

As a workaround, remove full-text search indexes prior to upgrading and rebuild full-

text search indexes after the upgrade is completed.

• Deprecation and Removal Notes

• Functionality Added or Changed

• Bugs Fixed

Deprecation and Removal Notes

• Previously, program options could be specified in full or as any unambiguous prefix. For example, the

--compress option could be given to mysqldump as --compr, but not as --comp because the latter

is ambiguous. Option prefixes now are deprecated. They can cause problems when new options are

implemented for programs. A prefix that is currently unambiguous might become ambiguous in the

future. If an unambiguous prefix is given, a warning now occurs to provide feedback. For example:

Warning: Using unique option prefix compr instead of compress is

deprecated and will be removed in a future release. Please use the

full name instead.

111

MySQL 5.6 Release Notes

Option prefixes are no longer supported in MySQL 5.7; only full options are accepted. (Bug #16996656,

WL #6978)

Functionality Added or Changed

• Incompatible Change: Previously, the Performance Schema statement instrumentation did not

include statements executed on a slave replication server. To address this, a new abstract instrument,

statement/rpl/relay_log, has been added to the setup_instruments table. This instrument

is used during the early stages of replicated statement classification before the exact statement type is

known.

In addition, the statement/com/ abstract statement instrument was renamed to statement/com/

new_packet.

Applications that refer to the old instrument names must be updated with the new names. For more

information about the use of abstract instruments in statement classification, see Performance Schema

Statement Event Tables. (Bug #16750433, Bug #17271055)

• Important Change; Replication: By default, when promoting integers from a smaller type on the

master to a larger type on the slave (for example, from a SMALLINT column on the master to a BIGINT

column on the slave), the promoted values are treated as though they are signed. Now in such cases

it is possible to modify or override this behavior using one or both of ALL_SIGNED, ALL_UNSIGNED

in the set of values specified for the slave_type_conversions server system variable. For more

information, see Row-based replication: attribute promotion and demotion, as well as the description of

the variable. (Bug #15831300)

• The C API libmysqlclient shared-library .so files now have version 18.1.0 (up from version 18.0.0

used in MySQL 5.5). 18.1.0 can be used as a replacement for 18.0.0. (Bug #16809055, Bug #59106,

Bug #12407476)

• In batch mode, mysql formatted result status messages such as “"Query OK, 1 row affected"” but did

not print them. Now these messages are not formatted. (Bug #69486, Bug #16971432)

Bugs Fixed

• Incompatible Change: It is possible for a column DEFAULT value to be valid for the sql_mode value at

table-creation time but invalid for the sql_mode value when rows are inserted or updated. Example:

SET sql_mode = '';

CREATE TABLE t (d DATE DEFAULT 0);

SET sql_mode = 'NO_ZERO_DATE,STRICT_ALL_TABLES';

INSERT INTO t (d) VALUES(DEFAULT);

In this case, 0 should be accepted for the CREATE TABLE but rejected for the INSERT. However,

previously the server did not evaluate DEFAULT values used for inserts or updates against the current

sql_mode. In the example, the INSERT succeeds and inserts '0000-00-00' into the DATE column.

The server now applies the proper sql_mode checks to generate a warning or error at insert or update

time.

A resulting incompatibility for replication if you use statement-based logging

(binlog_format=STATEMENT) is that if a slave is upgraded, a nonupgraded master will execute the

preceding example without error, whereas the INSERT will fail on the slave and replication will stop.

To deal with this, stop all new statements on the master and wait until the slaves catch up. Then upgrade

the slaves followed by the master. Alternatively, if you cannot stop new statements, temporarily change

112

MySQL 5.6 Release Notes

to row-based logging on the master (binlog_format=ROW) and wait until all slaves have processed all

binary logs produced up to the point of this change. Then upgrade the slaves followed by the master and

change the master back to statement-based logging. (Bug #68041, Bug #16078943)

• Important Change; Performance; InnoDB: InnoDB failed to open a tablespace that has multiple

data files. This removes the known limitation that was in MySQL Server 5.6.12. (Bug #17033706, Bug

#69623)

• Performance; InnoDB: A code regression introduced in MySQL 5.6 negatively impacted DROP TABLE

and ALTER TABLE performance. This could cause a performance drop between MySQL Server 5.5.x

and 5.6.x. (Bug #16864741, Bug #69316)

• Performance; InnoDB: When innodb_thread_concurrency is set to a nonzero value, there was

a possibility that all innodb_concurrency_tickets would be released after each row was read,

resulting in a concurrency check after each read. This could impact performance of all queries. One

symptom could be higher system CPU usage. We strongly recommend that you upgrade to MySQL

Server 5.6.13 if you use this setting. This could cause a performance drop between MySQL Server 5.5.x

and 5.6.x. (Bug #68869, Bug #16622478)

• InnoDB: A full-text search using the IN BOOLEAN MODE modifier would result in an assertion failure.

(Bug #16927092)

References: This issue is a regression of: Bug #16516193.

• InnoDB: When CHECK TABLE found a secondary index that contained the wrong number of entries, it

would report an error but not mark the index as corrupt. CHECK TABLE now marks the index as corrupt

when this error is encountered, but only the index is marked as corrupt, not the table. As a result, only

the index becomes unusable until it is dropped and rebuilt. The table is unaffected. (Bug #16914007)

• InnoDB: InnoDB would attempt to gather statistics on partially created indexes. (Bug #16907783)

• InnoDB: The server would crash during a memcached set operation. The failure was due to a padded

length value for a utf8 CHAR column. During a memcached update operation, a field from an old tuple

would be copied with a data length that was less than the padded utf8 CHAR column value. This fix

ensures that old tuples are not copied. Instead, a new tuple is created each time. (Bug #16875543)

• InnoDB: The two INFORMATION_SCHEMA tables for the InnoDB buffer pool could show an invalid page

type for read-fixed blocks. This fix will show the unknown page type for blocks that are I/O-fixed for

reading. (Bug #16859867)

• InnoDB: Removed invalid compilation warning messages that appeared when compiling the InnoDB

memcached plugin. (Bug #16816824)

• InnoDB: A memory leak would occur when inserting or replacing a row in a full-text search index on a

table with more than 96 columns. (Bug #16809167)

• InnoDB: During an insert buffer merge, InnoDB would invoke

lock_rec_restore_from_page_infimum() on a potentially invalid record pointer. (Bug

#16806366)

• InnoDB: The innodb_rwlock_x_spin_waits item in the

INFORMATION_SCHEMA.INNODB_METRICS table would show the same value as the

innodb_rwlock_x_os_waits item. (Bug #16798175)

• InnoDB: In debug builds, an assertion could occur in OPT_CHECK_ORDER_BY when using binary directly

in a search string, as binary may include NULL bytes and other non-meaningful characters. This fix will

remove non-meaningful characters before the search is run. (Bug #16766016)

113

MySQL 5.6 Release Notes

• InnoDB: Valgrind testing returned memory leak errors which resulted from a regression introduced by

the fix for Bug #11753153. The dict_create_add_foreign_to_dictionary function would call

pars_info_create but failed to call pars_info_free. (Bug #16754901)

• InnoDB: The page_zip_validate() consistency check failed after compressing a page, in

page_zip_compress(). This problem was caused by page_zip_decompress(), which failed to set

heap_no correctly when a record contained no user data bytes. A record with no user data bytes occurs

when, for example, a primary key is an empty string and all secondary index fields are NULL or an empty

string. (Bug #16736929)

• InnoDB: Some characters in the identifier for a foreign key constraint are modified during table exports.

(Bug #16722314, Bug #69062)

• InnoDB: Stale InnoDB memcached connections would result in a memory leak. (Bug #16707516, Bug

#68530)

• InnoDB: A race condition would occur between ALTER TABLE ... ADD KEY and INSERT statements,

resulting in an “Unable to Purge a Record” error. (Bug #16628233)

• InnoDB: Very large InnoDB full-text search (FTS) results could consume an excessive amount of

memory. This bug fix reduces memory consumption for FTS results and introduces a new configuration

parameter, innodb_ft_result_cache_limit, which places a default size limit of 2000000000

bytes on the InnoDB FTS query result cache. innodb_ft_result_cache_limit has an unlimited

maximum value and can be set dynamically. (Bug #16625973)

• InnoDB: During a transaction commit, prepare_commit_mutex is acquired to preserve the commit

order. If the commit operation failed, the transaction would be rolled back but the mutex would not be

released. Subsequent insert operations would not be able to acquire the same mutex. This fix frees

prepare_commit_mutex during innobase_rollback. (Bug #16513588)

• InnoDB: When the InnoDB shutdown mode (innodb_fast_shutdown) is set to 2 and the master

thread enters the flush loop, the thread would not be able to exit under some circumstances. This could

lead to a shutdown hang. (Bug #16411457)

• InnoDB: Restarting InnoDB in read-only mode and running a workload would occasionally return a

global_segment < os_aio_n_segments assertion. (Bug #16362046)

• InnoDB: While printing a UTF-8 table name, InnoDB would truncate the table name, resulting in an

incomplete buffer and subsequent Valgrind error. This bug fix also addresses an incorrect debugging

error message. (Bug #16066351)

• InnoDB: Attempting to create a table while in innodb_read_only mode resulted in the following error:

ERROR 1015 (HY000): Can't lock file (errno: 165 - Table is read only). (Bug

#15963619)

• InnoDB: Creating numerous tables, each with a full-text search index, could result in excessive memory

consumption. This bug fix adds a new configuration parameter, innodb_ft_total_cache_size,

which defines a global memory limit for full-text search indexes. If the global limit is reached by an index

operation, a force sync is triggered. (Bug #14834698, Bug #16817453)

• InnoDB: In the error log, a full-text search index would be reported missing from the data dictionary

during a TRUNCATE TABLE operation. After restarting mysqld, the following InnoDB error would be

reported: “InnoDB: Error: trying to load index idx13 for table test/g1 but the

index tree has been freed..” (Bug #12429565)

References: See also: Bug #17402002.

114

MySQL 5.6 Release Notes

• InnoDB: The row_check_index_for_mysql method, which checks for NULL fields during an index

scan or CHECK TABLE operation, would iterate unnecessarily. Thanks to Po-Chun Chang for the patch

to correct this issue. (Bug #69377, Bug #16896647)

• InnoDB: When running an InnoDB full-text search in boolean mode, prefixing an asterisk (*) to a search

string ('*string') would result in an error whereas for MyISAM, a prefixed asterisk would be ignored.

To ensure compatibility between InnoDB and MyISAM, InnoDB now handles a prefixed asterisk in the

same way as MyISAM. (Bug #68948, Bug #16660607)

• InnoDB: Successive deletes in descending key order would lead to under-filled InnoDB index pages.

When an InnoDB index page is under-filled, it is merged with the left or right sibling node. The check

performed to determine if a sibling node is available for merging was not functioning correctly. (Bug

#68501, Bug #16417635)

• InnoDB: Setting foreign_key_checks=0 and running ALTER TABLE to change the character set

of foreign key columns for a database with multiple tables with foreign key constraints would leave the

database in an inconsistent state. Subsequent ALTER TABLE operations (using the COPY algorithm)

with foreign_key_checks=1 would fail due to the detected inconsistency. Reversion of the partially

executed ALTER TABLE operation would also fail, resulting in the loss of the table being altered. When

running the same ALTER TABLE operation with a RENAME clause, the inconsistency would not be

detected but if the ALTER TABLE operation failed for some other reason, reversion of the partially

executed ALTER TABLE failed with the same result.

The bug fix temporarily disables foreign_key_checks while the previous table definition is restored.

(Bug #65701, Bug #14227431)

• InnoDB: Creating a table with a comment or default textual value containing an apostrophe that is

escaped with a backslash would sometimes cause the InnoDB storage engine to omit foreign key

definitions. (Bug #61656, Bug #12762377)

• InnoDB: The pthread_mutex, commit_threads_m, which was initialized but never used, has been

removed from the code base. (Bug #60225, Bug #11829813)

• Partitioning: When upgrading to MySQL 5.5.31 or higher, a message is written into the output of

mysql_upgrade when encountering a partitioned table for which the ALGORITHM option is required

to maintain binary compatibility with the original; the message includes the ALTER TABLE statement

required to make the change. For such a table having a sufficiently large number of partitions, the

message was truncated with an error before the complete ALTER TABLE statement could be written.

(Bug #16589511)

• Partitioning: When a range was specified in the WHERE condition of a query against a table partitioned

by range, and the specified range was entirely within one of the partitions, the next partition was also

checked for rows although it should have been pruned away.

Suppose we have a range-partitioned table t created using the following SQL statement:

CREATE TABLE t (

id INT AUTO_INCREMENT,

dt DATETIME,

PRIMARY KEY (dt,id),

UNIQUE KEY (id,dt)

)

PARTITION BY RANGE COLUMNS(dt) (

PARTITION p0 VALUES LESS THAN ('2013-01-01'),

PARTITION p1 VALUES LESS THAN ('2013-01-15'),

PARTITION p2 VALUES LESS THAN ('2013-02-01'),

PARTITION p3 VALUES LESS THAN ('2013-02-15'),

PARTITION pmax VALUES LESS THAN (MAXVALUE)

);

115

MySQL 5.6 Release Notes

An example of a query that exhibited this issue when run against t is shown here:

SELECT COUNT(*) FROM t

WHERE dt >= '2013-02-01' AND dt < '2013-02-15';

In this case, partition pmax was checked, even though the range given in the WHERE clause lay entirely

within partition p3. (Bug #16447483)

• Partitioning: When dropping a partitioned table, the table's .par file was deleted first, before the table

definition or data. This meant that, if the server failed during the drop operation, the table could be left in

an inconsistent state in which it could neither be accessed nor dropped.

The fix for this problem makes the following changes:

• Now, when dropping a partitioned table, the table's .par file is not removed until all table data has

been deleted.

• When executing DROP TABLE of a partitioned table, in the event that its .par file is determined to be

missing, the table's .frm file is now immediately deleted, in effect forcing the drop to complete.

(Bug #13548704, Bug #63884)

• Replication: The condition leading to the issue fixed in Bug #16579083 continued to raise an error even

though the condition itself no longer cause the issue to occur. (Bug #16931177, Bug #69369)

References: See also: Bug #16271657, Bug #16491597, Bug #68251, Bug #68569. This issue is a

regression of: Bug #16579083.

• Replication: When rpl_semi_sync_master_timeout was set to an extremely large value,

semisynchronous replication became very slow, especially when many sessions were working in

parallel. It was discovered that the code to calculate this timeout was inside the wait loop itself, with the

result that an increase in the value of rpl_semi_sync_master_timeout caused repeated iterations.

This fix improves the method used to calculate wakeup times, and moves it outside of the wait loop, so

that it is executed one time only. (Bug #16878043, Bug #69341)

• Replication: It was possible to cause a deadlock after issuing FLUSH TABLES WITH READ LOCK by

issuing STOP SLAVE in a new connection to the slave, then issuing SHOW SLAVE STATUS using the

original connection.

The fix for this includes the addition of the rpl_stop_slave_timeout system variable, to control the

time in seconds to wait for slave to stop after issuing STOP SLAVE before returning a warning. (Bug

#16856735)

• Replication: Some expressions employing variables were not handled correctly by LOAD DATA. (Bug

#16753869)

• Replication: In some circumstances, the message in the Last_Error column from the output of SHOW

SLAVE STATUS referred to GTID_NEXT_LIST although this variable is not currently implemented (the

name is reserved for possible future use). Now in such cases the error message no longer refers to this

variable. (Bug #16742886, Bug #69096)

References: See also: Bug #16715809, Bug #69045.

• Replication: Linker errors occurred if the header file log_event.h was included in an application

containing multiple source files, because the file rpl_tblmap.cc was included in log_event.h.

This fix moves the inclusion of rpl_tblmap.cc into the source files that use log_event.h. (Bug

#16607258)

116

MySQL 5.6 Release Notes

• Replication: The error displayed by SHOW SLAVE STATUS when a worker thread fails to apply an event

contained no event coordinate information. The GTID for the event's group was also not shown. Now

in such cases, the text shown for Last_SQL_Error is prefixed with the (physical) master binary log

coordinates, as well as the value of gtid_next when this has been set. (Bug #16594095)

• Replication: The warning issued when specifying MASTER_USER or MASTER_PASSWORD with CHANGE

MASTER TO was unclear for a number of reasons, and has been changed to read, Storing MySQL

user name or password information in the master info repository is not secure

and is therefore not recommended. Please consider using the USER and PASSWORD

connection options for START SLAVE; see 'START SLAVE Syntax' in the MySQL

Manual for more information. (Bug #16460123, Bug #16461303, Bug #68602, Bug #68599)

• Replication: After a transaction was skipped due to its GTID already having been logged, all remaining

executed transactions were incorrectly skipped until gtid_next was pointed to a different GTID.

To avoid this incorrect behavior, all transactions—even those that have been skipped—are marked

as undefined when they are commited or rolled back, so that an error is thrown whenever a second

transaction is executed following the same SET @@SESSION.gtid_next statement. (Bug #16223835)

• Replication: After the client thread on a slave performed a FLUSH TABLES WITH READ LOCK and

was followed by some updates on the master, the slave hung when executing SHOW SLAVE STATUS.

(Bug #68460, Bug #16387720)

• The optimizer failed to check a function return value for an area calculation, leading to a server exit. (Bug

#23280059)

• Reads from message buffers for closed connections could occur. (Bug #17003702)

• The server could exit while using a cursor to fetch rows from a UNION query. (Bug #16983143)

• Sql_condition::set_subclass_origin() could perform an out-of-bounds read. (Bug #16969091)

• The range optimizer incorrectly assumed that any geometry function on a spatial index returned rows in

ROWID order, which could result in incorrect query results. (Bug #16960800)

• Initialization of keycache_* variables (see Multiple Key Caches) during server startup could write to

incorrect memory. (Bug #16945503)

• For debug builds, improper use of SAFE_MUTEX within dbug.c caused different code areas to have

different ideas about size and contents of a mutex. This could result in out-of-bounds memory writes.

(Bug #16945343)

• The Performance Schema could spawn a thread using incorrect instrumentation information. (Bug

#16939689)

• The server did excessive locking on the LOCK_active_mi and active_mi->rli->data_lock

mutexes for any SHOW STATUS LIKE 'pattern' statement, even when the pattern did not match

status variables that use those mutexes (Slave_heartbeat_period, Slave_last_heartbeat,

Slave_received_heartbeats, Slave_retried_transactions, Slave_running). Now

attempts to show those variables do not lock those mutexes. This might result is slightly stale data, but

better performance. (Bug #16904035)

• Full-text phrase search in InnoDB tables could read incorrect memory. (Bug #16885178)

• It was not possible to keep several major versions of MySQL in the same yum repository. (Bug

#16878042)

• INSERT ... ON DUPLICATE KEY UPDATE could cause a server exit if a column with no default value

was set to DEFAULT. (Bug #16756402)

117

MySQL 5.6 Release Notes

References: This issue is a regression of: Bug #14789787.

• In a prepared statement or stored routine, if the HAVING clause of a subquery referenced some column

of the GROUP BY of the parent query, the server could exit. (Bug #16739050)

• Compiling failed with -DMY_ATOMIC_MODE_RWLOCKS=1 or on platforms on which MySQL did not

support lockless atomic operations (such as ARM). (Bug #16736461)

• The code base was modified to account for new warning checks introduced by gcc 4.8. (Bug

#16729109)

• The runtime open_files_limit system variable did not show the actual number of file descriptors

the mysqld process could have, but instead the number that was requested after adjusting the value

specified at startup. (Bug #16657588)

• The server could make the wrong decision about whether an account password was expired. (Bug

#16604641)

• Some rows for a session could be missing sporadically from the session_connect_attrs

Performance Schema table while the session was executing a workload. (Bug #16576980)

• Upgrading from community SLES RPM packages to commercial packages for the same MySQL version

failed with conflict errors. (Bug #16545296)

• If the optimizer was using a Loose Index Scan, the server could exit while attempting to create a

temporary table. (Bug #16436567)

• Incorrect results or a server exit could be caused by a reference to an aggregated expression inside a

nested subquery, where the aggregated expression was evaluated in a query block more than two levels

outer to the reference. (Bug #16436383)

• Unlike MyISAM, InnoDB does not support boolean full-text searches on nonindexed columns, but this

restriction was not enforced, resulting in queries that returned incorrect results. (Bug #16434374)

• A full-text search syntax error failed to print to standard output. (Bug #16429688, Bug #16765397)

• A server exit could occur for queries of the form SELECT (SELECT 1 FROM t1) IN (SELECT a

FROM t1) when attempting to evaluate the constant left-hand argument to the IN subquery predicate.

(Bug #16369522)

• An assertion could be raised when creating a index on a prefix of a TINYBLOB or GEOMETRY column in

an InnoDB column. (Bug #16368875, Bug #18776592, Bug #17665767)

• In debug builds, failure in the range optimizer for an ER_LOCK_DEADLOCK or ER_LOCK_WAIT_TIMEOUT

error could go undetected and cause an assertion to be raised when a response was sent to the client.

In release builds, this problem manifested as clients receiving an OK for a statement that had failed. (Bug

#16366994, Bug #16247110)

• Transforming some subqueries that select temporal or BIGINT types or to a semijoin caused a server

exit on the second execution of prepared statements or stored programs. (Bug #16319671)

• The server could exit in do_copy_not_null() due to an improper NULL-value check. (Bug

#16316564)

• No warning was generated if a duplicate index existed after dropping a column associated with a

multiple-column index. (Bug #16315351)

• SELECT DISTINCT with WITH ROLLUP could result in a Duplicate entry 'NULL' for key

'<auto_key>' error. (Bug #16314835)

118

MySQL 5.6 Release Notes

• The usual failed-login attempt accounting was not applied to failed COM_CHANGE_USER commands. (Bug

#16241992, Bug #17357535)

• A user variable referenced during execution of a prepared statement is set to memory that is freed at the

end of execution. A second execution of the statement could result in Valgrind warnings when accessing

this memory. (Bug #16119355)

• Misoptimization of left expressions in prepared statements could cause a server exit. (Bug #16095534)

• The optimizer trace could print ranges for key parts that were not usable for range access. (Bug

#14615536)

• Passwords in statements were not obfuscated before being written to the audit log. (Bug #14536456)

• When running a query on INFORMATION_SCHEMA.INNODB_BUFFER_PAGE that requested

table_name and index_name values, query results would include index pages without table_name

or index_name values. (Bug #14529666)

• Several COM_xxx commands in the client-server protocol did not have length checks for incoming

network packets, which could result in various problems for malformed input. (Bug #14525642)

• With the thread pool plugin in use, normal connection termination caused the Aborted_clients status

variable to be incremented. (Bug #14081240)

• On Windows, command-line options of the form --opt_name="opt_value" worked but

--opt_name='opt_value' did not.

On all platforms, for Performance Schema options of the form --

performance_schema_instrument="instrument=value", invalid instrument names now are

rejected. (Bug #13955232)

• MySQL Installer, if run in custom install or change mode, offered installation options that had no effect.

(Bug #12928601)

• Incorrect results could be returned from queries that used several aggr_func(DISTINCT) functions

(where aggr_func() is an aggregate function such as COUNT()) when these referred to different

columns of the same composite key. (Bug #12328597)

• RPM packages did not provide lowercase tags for their contents. For example, a server RPM indicated

that it provided MySQL-server, but not mysql-server. (Bug #69830, Bug #17211588)

• When selecting a union of an empty result set (created with WHERE 1=0 or WHERE FALSE) with a

derived table, incorrect filtering was applied to the derived table. (Bug #69471, Bug #16961803)

References: This issue is a regression of: Bug #15848521.

• For queries with ORDER BY ... LIMIT, the optimizer could choose a nonordering index for table

access. (Bug #69410, Bug #16916596)

• When an internal buffer was too small for the workload, the Performance Schema could spend a lot

of time in an internal spin loop attempting to allocate a memory buffer, and fail. (Bug #69382, Bug

#16945618)

• In the absence of SQL_CALC_FOUND_ROWS in the preceding query, FOUND_ROWS() should return the

number of rows in the result set, but this did not always happen if the query contained ORDER BY. (Bug

#69271, Bug #16827872)

• Full-text search on InnoDB tables failed on searches for words containing apostrophes. (Bug #69216,

Bug #16801781)

119

MySQL 5.6 Release Notes

• If an UPDATE containing a subquery caused a deadlock inside InnoDB, the deadlock was not properly

handled by the SQL layer. The SQL layer then tried to unlock the row after InnoDB rolled back the

transaction, raising an assertion inside InnoDB. (Bug #69127, Bug #16757869)

• Some LEFT JOIN queries with GROUP BY could return incorrect results. (Bug #68897, Bug #16620047)

References: This issue is a regression of: Bug #11760517.

• Comparison of a DATETIME value and a string did not work correctly for the utf8_unicode_ci

collation. (Bug #68795, Bug #16567381)

• Full-text search on InnoDB tables failed on searches for literal phrases combined with + or - operators.

(Bug #68720, Bug #16516193)

• Optimizations that used extended secondary keys (see Use of Index Extensions) worked only for

InnoDB, even for storage engines with the requisite underlying capabilities. (Bug #68469, Bug

#16391678)

• mysql_install_db incorrectly tried to create the mysql.innodb_table_stats and

mysql.innodb_index_stats tables if InnoDB was not available. (Bug #68438, Bug #16369955)

• mysqldump assumed the existence of the general_log and slow_log tables in the mysql database.

It failed if invoked to dump tables from an older server where these tables do not exist. (Bug #65670,

Bug #14236170)

• Attempts to build from a source RPM package could fail because the build process attempted to refer to

a pb2user that might not exist. (Bug #64641, Bug #13865797, Bug #69339, Bug #16874980)

• If one session had any metadata lock on a table, another session attempting CREATE TABLE [IF

NOT EXISTS] for the same table would hang. This occurred due to an attempt in the second session

to acquire an exclusive metadata lock on the table before checking whether the table already existed.

An exclusive metadata lock is not compatible with any other metadata locks, so the session hung for the

lock timeout period if another session had the table locked.

Now the server attempts to acquire a shared metadata lock on the table first to check whether it exists,

then upgrade to an exclusive lock if it does not. If the table does exist, an error occurs for CREATE

TABLE and a warning for CREATE TABLE IF NOT EXISTS. (Bug #63144, Bug #13418638)

• sql-common/client_plugin.c contained a nonportable use of a va_list parameter. (Bug #62769,

Bug #13252623)

• Unoptimized versions of the xxxkorr() macros in my_global.h were used on 64-bit x86 processors.

(Bug #61179, Bug #12565703)

• A typo in cmake/dtrace.cmake prevented DTrace support from being enabled by -

DENABLE_DTRACE-on. (Bug #60743, Bug #12325449)

• Boolean plugin system variables did not behave well on machines where char is unsigned; some code

attempted to assign a negative value to these. (Bug #59905, Bug #11864205)

• With big_tables enabled, queries that used COUNT(DISTINCT) on a simple join with a constant

equality condition on a non-duplicate key returned incorrect results. (Bug #52582, Bug #11760197)

References: See also: Bug #18853696.

Changes in MySQL 5.6.12 (2013-06-03, General Availability)

Known limitations of this release:

120

MySQL 5.6 Release Notes

Important

InnoDB may fail to open a tablespace that has multiple data files due to newly

introduced corruption checking functionality. It is recommended that you do not

upgrade to this version if you have more than one file for your shared InnoDB

tablespace. If you have upgraded to an affected version and the server no longer

starts, you can upgrade to a later version when it becomes available or downgrade

to an earlier version.

Note

If you have InnoDB tables with full-text search indexes and you are upgrading from

MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server

will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.

As a workaround, remove full-text search indexes prior to upgrading and rebuild full-

text search indexes after the upgrade is completed.

• Functionality Added or Changed

• Bugs Fixed

Functionality Added or Changed

• mysql_upgrade now verifies that the server version matches the version against which it was

compiled, and exits if there is a mismatch. In addiion, a --version-check option permits specifying

whether to enable version checking (the default), or disable checking if given as --skip-version-

checking. (Bug #16500013)

Bugs Fixed

• Incompatible Change: When used for an existing MySQL account, the GRANT statement could produce

unexpected results if it included an IDENTIFIED WITH clause that named an authentication plug

differing from the plugin named in the corresponding mysql.user table row.

Because IDENTIFIED WITH is intended only for GRANT statements that create a new user, it is now

prohibited if the named account already exists. (Bug #16083276)

• Important Change; Replication: When the server was running with --binlog-ignore-db and

SELECT DATABASE() returned NULL (that is, there was no currently selected database), statements

using fully qualified table names in dbname.tblname format were not written to the binary log. This was

because the lack of a currently selected database in such cases was treated as a match for any possible

ignore option rather than for no such option; this meant that these statements were always ignored.

Now, if there is no current database, a statement using fully qualified table names is always written to the

binary log. (Bug #11829838, Bug #60188)

• InnoDB; Partitioning: Joins involving partitioned InnoDB tables having one or more BLOB columns

were not always handled correctly. The BLOB column or columns were not required to be join columns,

or otherwise to be named or referenced in the statement containing the join, for this issue to occur. (Bug

#16367691)

• InnoDB: In debug builds, an online ALTER TABLE operation that performed a full table copy would

raise an assertion. The assertion was due to a race condition that would occur during BLOB retrieval,

when applying the table modification log to any log block except for the very last one. This fix modifies

row_log_table_apply_convert_mrec() to ensure that an index B-tree lock is acquired to protect

the access to log->blobs and the BLOB page. (Bug #16774118)

121

MySQL 5.6 Release Notes

• InnoDB: When the function trx_rollback_or_clean_recovered() rolls back or cleans

up transactions during a crash recovery, it removes the trx objects from the trx_sys list

without freeing up the memory used by those objects. To prevent a memory leak, this fix adds

trx_free_for_background() calls to trx_rollback_resurrected(), the function that removes

the trx objects. (Bug #16754776)

• InnoDB: A memory leak would occur in dict_check_tablespaces_and_store_max_id() when

space_id is equal to zero. (Bug #16737332)

• InnoDB: A missing comma in SHOW STATUS output would break MySQL Enterprise Monitor parsing.

(Bug #16723686)

• InnoDB: After a clean shutdown, InnoDB does not check .ibd file headers at startup. As a result, in a

crash recovery scenario, InnoDB could load a corrupted tablespace file. This fix implements consistency

and status checks to avoid loading corrupted files. (Bug #16720368)

• InnoDB: This fix addresses a race condition that would occur between the rollback of a recovered

transaction and creation of a secondary index in a locked operation. The race condition would corrupt

the secondary index. (Bug #16593427)

• InnoDB: DML operations on compressed temporary tables would result in a Valgrind error in the buffer

manager stack. (Bug #16593331)

• InnoDB: For ALTER TABLE operations on InnoDB tables that required a table-copying operation,

other transactions on the table might fail during the copy. However, if such a transaction issued a partial

rollback, the rollback was treated as a full rollback. (Bug #16544143)

• InnoDB: The recv_writer thread would only start after all redo log scans finished. In the case

of multiple redo log scans, accumulated redo records would be applied after each scan and before

processing the next scan. The absence of the recv_writer thread to help with flushing would slow

recovery or result in a server startup timeout. This fix ensures that the recv_writer thread starts

before the first scan batch is processed. (Bug #16501172)

• InnoDB: Under certain circumstances, LRU flushing would take a long time possibly affecting all flushing

activity and causing a shutdown timeout. (Bug #16500209)

• InnoDB: The InnoDB memcached test.demo_test table failed to work when defined as a utf8

charset table. (Bug #16499038)

• InnoDB: In cases where threads are forced to do single page flushing, fsync() would be triggered for

all data files. This fix allows for synchronous single page flushing. (Bug #16477781)

• InnoDB: This fix removes most calls to OS_THREAD_SLEEP from InnoDB. (Bug #16472953, Bug

#68588)

• InnoDB: FLUSH TABLES ... FOR EXPORT slept too often while flushing pages from buffer pools.

(Bug #16471701)

• InnoDB: Concurrently inserting into a full-text table would cause some inserts to fail. Duplicate values

would be generated for full-text search document IDs when performing inserts into a hidden full-text

search document ID column. (Bug #16469399)

• InnoDB: The page_zip_available function would count some fields twice. (Bug #16463505)

• InnoDB: This fix replaces the IB_ULONGLONG_MAX constant with LSN_MAX where the code refers to

log sequence numbers, or with TRX_ID_MAX where trx->no is initialized to an undefined value. This

change does not alter the value of the constant. (Bug #16458660)

122

MySQL 5.6 Release Notes

• InnoDB: This fix corrects the text for InnoDB error 6025, which stated, “InnoDB: read can't be opened

in ./ib_logfile0 mode.”. The corrected message states, “InnoDB: ./ib_logfile0 can't be opened in read

mode.” The variable and mode in the message construct were transposed. (Bug #16434398)

• InnoDB: Creating a foreign key constraint using the ALTER TABLE INPLACE algorithm requires

foreign_key_checks to be set to 0 (SET foreign_key_checks = 0;). As a result, an appropriate

duplicate ID check would not be performed. (Bug #16413976)

• InnoDB: In debug builds, an insert failed with an invalid assertion: sync_thread_levels_g(array,

level - 1, TRUE). (Bug #16409715)

• InnoDB: Multiple concurrent calls to dict_update_statistics() would result in unnecessary server

load. (Bug #16400412)

• InnoDB: On 64-bit Windows builds, INNODB_BUFFER_POOL_SIZE would not accept an allocation of

more than 32GB. This limitation was due to a bug that truncated the internal value for the InnoDB buffer

pool size to 32 bits on 64-bit Windows builds. (Bug #16391722, Bug #68470)

• InnoDB: DROP DATABASE failed if the database contained an InnoDB table that had a data file in an

external data directory. The external data file had an “InnoDB Symbolic Link” file type (.isl) that was

not recognized by MySQL. This fix adds .isl as a known InnoDB file type. (Bug #16338667)

• InnoDB: RENAME TABLE would result in a hang due to a MySQL mutex acquisition deadlock. (Bug

#16305265)

• InnoDB: Under testing, a FLUSH TABLES operation resulted in a timeout due to a missing

acknowledgment that the purge thread had stopped. (Bug #16277387)

• InnoDB: For compressed tables, a page reorganize operation would always write

an MLOG_ZIP_PAGE_REORGANIZE record to the redo log, which is only correct if

innodb_log_compressed_pages=OFF. When innodb_log_compressed_pages=ON, the page

reorganize operation should log the compressed page image. (Bug #16267120)

• InnoDB: When tables are linked by foreign key constraints, loading one table would open other linked

tables recursively. When numerous tables are linked by foreign key constraints, this would sometimes

lead to a thread stack overflow causing the server to exit. Tables linked by foreign key constraints are

now loaded iteratively. Cascade operations, which were also performed in a recursive manner, are now

performed iteratively using an explicit stack. (Bug #16244691, Bug #65384)

• InnoDB: After disabling foreign key checks with SET foreign_key_checks=0 and performing a

DROP INDEX, the table was no longer accessible after restarting the server. This fix allows the table

with missing foreign key indexes to be accessed when SET foreign_key_checks=0. When the

table is accessible, the user must recreate the missing indexes to fulfill the foreign key constraints. (Bug

#16208542, Bug #68148)

• InnoDB: When a transaction is in READ COMMITTED isolation level, gap locks are still taken in

the secondary index when a row is inserted. This occurs when the secondary index is scanned

for duplicates. The function row_ins_scan_sec_index_for_duplicate() always calls the

function row_ins_set_shared_rec_lock() with LOCK_ORDINARY irrespective of the transaction

isolation level. This fix modifies the row_ins_scan_sec_index_for_duplicate() function to call

row_ins_set_shared_rec_lock() with LOCK_ORDINARY or LOCK_REC_NOT_GAP, based on the

transaction isolation level. (Bug #16133801, Bug #68021)

• InnoDB: Starting mysqld with --innodb-log-buffer-size=50GB failed to allocate memory and

returned NULL. For non-debug builds there was no check in place and a segmentation fault occurred.

This fix adds a log message stating that memory failed to be allocated, and adds an assertion. (Bug

#16069598, Bug #68025)

123

MySQL 5.6 Release Notes

• InnoDB: When UNIV_DEBUG is enabled in debug builds, buf_validate() is often called which

sometimes results in false alarms in tests on semaphore wait timeout. This fix increases counter values

to reduce false alarms. (Bug #16068056)

• InnoDB: The explain_filename function, which provides information about a partition by parsing the

file name, would return an error when attempting to parse a file name with no partition information. (Bug

#16051728)

• InnoDB: Stopping the server, removing a database table (d1.t1) .frm file from the data directory,

restarting the server, and dropping the database (d1), would cause an assertion. (Bug #16043216)

• InnoDB: While processing read-write workloads, InnoDB would scan more pages than are required for

flushing, unnecessarily consuming CPU resource. (Bug #16037180)

• InnoDB: An active FLUSH TABLES ... FOR EXPORT thread would cause a hang during shutdown.

The fix ensures that trx_is_interrupted() is checked during ibuf_merge. (Bug #15953255)

• InnoDB: A multi-row INSERT ... ON DUPLICATE KEY UPDATE insert failure, caused by a duplicate

key error, would result in duplicate auto-increment values. (Bug #14483484, Bug #66301)

• Replication: Issuing a FLUSH TABLES statement on a GTID-enabled master caused replication to

fail. It was found that this misbehavior was introduced by the fix for Bug #16062608, which disallowed

statements that perform an implicit commit but whose changes are not logged when gtid_next is

set to any value other than AUTOMATIC. The changes made in that fix have been reverted, and such

statements are (again) allowed without regard to the value of this variable. (Bug #16715809, Bug

#69045)

References: Reverted patches: Bug #16062608.

• Replication: Point-in-time recovery could fail when trying to restore a single database from a binary log

in row-based format using mysqlbinlog with the --database option. (Bug #16698172)

• Replication: A crash-on-commit error caused InnoDB to lose the previous transaction following

execution of a RESET MASTER statement. This occurred because the prepare phase caused a flush to

disk, while the commit phase did not perform a corresponding flush within InnoDB.

To fix this problem, RESET MASTER now causes storage engine logs to be flushed on commit. (Bug

#16666456, Bug #68932)

• Replication: When processing an Update_rows_log_event or Delete_rows_log_event from

the binary log, the before image is hashed and stored in a hash table. Following this, the original

table is scanned for the desired records; subsequent processing hashes each record fetched from the

original table and performs a lookup for it in the hash table. However, columns read from the image that

had originally been set to NULL could instead contain random or “garbage” data, causing the lookup

(and thus replication) to fail with an error such as Could not execute Update_rows event on

table.... (Bug #16621923)

References: See also: Bug #11766865. This issue is a regression of: Bug #16566658.

• Replication: When used with the options --dump-slave --include-master-host-port,

mysqldump printed the port number within quotation marks, as if it were a string value rather than an

integer. (Bug #16615117)

• Replication: Due to time resolution issues on some systems, the time to be taken by the dump

thread for a reply from the slave could be calculated to be less than zero, leading to Semi-sync

master wait for reply fail to get wait time errors. Since this condition does not have a

negative impact on replication, errors caused by these conditions have been reduced to warnings. (Bug

#16579028)

124

MySQL 5.6 Release Notes

• Replication: Trying to update a column, previously set to NULL, of a table with no primary key caused

replication to fail with Can't find record in 'table'....

This issue was originally fixed in MySQL 5.6.3 but was inadvertently reintroduced in MySQL 5.6.6. (Bug

#16566658)

References: See also: Bug #16621923. This issue is a regression of: Bug #11766865.

• Replication: Running the server with --log-slave-updates together with --replicate-wild-

ignore-table or --replicate-ignore-table in some cases caused updates to user variables not

to be logged. (Bug #16541422)

• Replication: When using mysqlbinlog and the mysql client to roll forward two or more binary logs on

a server having GTIDs enabled, the gtid_next variable was not properly reset when switching from the

first to the second binary log, causing processing to halt with an error at that point. (Bug #16532543)

• Replication: The mysqlbinlog options --include-gtids, --exclude-gtids, and --skip-

gtids did not work correctly when trying to process multiple files. (Bug #16517775)

• Replication: When one or more GTID log events but no previous GTIDs log events were found in the

binary log, the resulting error was mishandled and led to a failure of the server. (This is an extremely rare

condition that should never occur under normal circumstances, and likely indicates that the binary log

file has somehow been corrupted.) Now in such cases, an appropriate error is issued, and is handled

correctly. (Bug #16502579, Bug #68638)

• Replication: Attempting to execute START SLAVE after importing new slave_master_info and

slave_relay_log_info tables failed with an empty error message. Now an appropriate error and

message are issued in such cases. (Bug #16475866, Bug #68605)

• Replication: Restarting the server after the slave_relay_log_info table had been emptied caused

mysqld to fail while trying to return an error. (Bug #16460978, Bug #68604)

• Replication: Extra binary log rotations were performed due to concurrent attempts at rotation when the

binary log became full, which were allowed to succeed. This could lead to the unnecessary creation of

many small binary log files. (Bug #16443676, Bug #68575)

• Replication: When the size of an execution event exceeded the maximum set for the buffer

(slave_pending_jobs_size_max), row-based replication could hang with Waiting for slave

workers to free pending events. (Bug #16439245, Bug #68462)

• Replication: Following disconnection from the master, the slave could under certain conditions

report erroneously on reconnection that it had received a packet that was larger than

slave_max_allowed_packet, causing replication to fail. (Bug #16438800, Bug #68490)

• Replication: An SQL thread error during MTS slave recovery caused the slave to fail. (Bug #16407467,

Bug #68506)

• Replication: When using the options --read-from-remote-server --stop-never --base64-

output=decode-rows --verbose, mysqlbinlog failed to reset the counter used to store the current

position within the file when the binary log on the server was rotated. (Bug #16316123, Bug #68347)

• Replication: When using mysqldump to back up a database created with MySQL 5.6.4 or an earlier

version, setting --set-gtid-purged=AUTO caused the backup to fail, because pre-5.6.5 versions of

MySQL did not support GTIDs, and it could not be determined if GTIDs were enabled for the database.

This fix makes sure mysqldump does not attempt to output a SET @@GLOBAL.gtid_purged statement

when backing up any pre-5.6.5 databases. (Bug #16303363, Bug #68314)

125

MySQL 5.6 Release Notes

• Replication: Deadlocks could sometimes occur on group commits with a high number of concurrent

updates, as well as when one client held a lock from a commit while another client imposed a lock while

rotating the binary log. (Bug #16271657, Bug #16491597, Bug #68251, Bug #68569)

• Replication: When semisynchronous replication was enabled, the automatic dropping on the master of

an event created using ON COMPLETION NOT PRESERVE caused the master to fail. (Bug #15948818,

Bug #67276)

• Replication: Setting a SET column to NULL inside a stored procedure caused replication to fail. (Bug

#14593883, Bug #66637)

• Replication: The binary log contents got corrupted sometimes, because the function

MYSQL_BIN_LOG::write_cache always thought it had reached the end-of-cache when the function

my_b_fill() reported a '0,' while that could also mean an error had occurred. This fix makes sure that

whenever my_b_fill() returns a '0,' an error check is performed on info->error. (Bug #14324766,

Bug #60173)

• Replication: PURGE BINARY LOGS by design does not remove binary log files that are in use or active,

but did not provide any notice when this occurred. Now, when log files are not removed under such

conditions, a warning is issued; this warning includes information about the file or files were not removed

when the statement was issued. (Bug #13727933, Bug #63138)

• Replication: When replicating to a BLACKHOLE table using the binary logging format, updates and

deletes cannot be applied and so are skipped. Now a warning is generated for this whenever it occurs.

Note

binlog_format=STATEMENT is recommended when replicating to tables that

use the BLACKHOLE storage engine.

(Bug #13004581)

• Removing a server RPM package did not shut down the existing server if it was running. (Bug

#16798868)

• Overhead for setting PROCESSLIST_STATE values in the THREADS Performance Schema table has

been reduced. (Bug #16633515)

• The Windows authentication plugin failed to free a context buffer for each connection. (Bug #16591288)

• The DBUG_PRINT() macro unnecessarily evaluated arguments when debugging was not enabled. (Bug

#16556597)

• Geometry methods that worked with WKB data performed insufficient input data validation, which could

cause Valgrind errors or a server exit. (Bug #16510712, Bug #12772601)

• The server could attempt a filesort operation for a zero-size sort length, causing it to exit. (Bug

#16503160)

• Opening a cursor on a SELECT within a stored procedure could cause a segmentation fault. (Bug

#16499751)

References: This issue is a regression of: Bug #14740889.

• my_load_defaults() was modified to accommodate some problems under compilation with gcc

4.7.2 that could cause a client crash during option processing. (Bug #16497125)

• SET PASSWORD treated user@'%' and user@'' as referring to the same mysql.user table row. (Bug

#16488043)

126

MySQL 5.6 Release Notes

• When index condition pushdown was used on a descending range scan and the first range interval

did not contain any qualifying records, the result of the range scan could be empty even if other range

intervals contained qualifying records. (Bug #16483273)

• The WKB reader for spatial operations could fail and cause a server exit. (Bug #16451878)

• Optimizer heuristics inappropriately preferred range access over ref access in cases when the ref

access referred to a column of a table earlier in the join seqence. (Bug #16437940)

• Performance Schema parameter autosizing at startup did not take into account later autosizing changes

to other startup parameters on which the Performance Schema parameters depended. (Bug #16430532)

• Some INFORMATION_SCHEMA queries that used ORDER BY did not use a filesort optimization as

they did in MySQL 5.5. (Bug #16423536)

• Manually-created accounts (using INSERT) with a malformed password effectively had no password.

(Bug #16414396)

• For debug builds, DBUG_EXPLAIN resulted in a buffer overflow when the debug system variable value

was more than 255 characters. (Bug #16402143)

• Several scripts in the sql-bench directory that were supposed to be executable did not have the

executable access bit set. (Bug #16395606)

• For debug builds, with an XA transaction in IDLE or PREPARED status, execution of a query with the

query cache enabled could cause a server exit. (Bug #16388996)

• Installing Debian packages on Ubuntu 12.10 succeeded using dpkg, but not with Software Center

5.4.1.4. (Bug #16387513)

• Within an XA transaction in ACTIVE state, statements causing an implicit commit could result in

metadata locks being released too early. (Bug #16362832)

• For debug builds, GROUP_CONCAT(... ORDER BY) within an ORDER BY clause could cause a server

exit. (Bug #16347426)

• A GROUP_CONCAT() invocation containing subquery having an outer reference caused the server to

exit. (Bug #16347343)

• The validate_password plugin did not always enforce appropriate constraints against assigning

empty passwords. (Bug #16346443)

• Re-execution of a stored procedure could cause a server exit in Item_field::fix_outer_field.

(Bug #16317443)

• For debug builds, the server could exit for queries involving a nested subquery, a subquery transformed

into a semijoin and using a view. (Bug #16317076)

• thread_pool_high_priority_connection could not be set at server startup. (Bug #16310373)

• With secure_auth enabled, a user with a password that used the pre-4.1 (old) hashing could not

update it to use the 4.1 (new) hashing. (Bug #16304018)

• The range optimizer could set up incorrect ranges for queries that used XOR operations. (Bug

#16272562)

• mysql_secure_installation could not connect to the server if the account used had an

expired password. It invoked mysql noninteractively, resulting in that program failing to connect.

Now mysql supports a --connect-expired-password option that indicates to the server that

127

MySQL 5.6 Release Notes

it can handle sandbox mode for expired-password accounts even if invoked noninteractively, and

mysql_secure_installation invokes mysql with this option. (Bug #16248315)

• If Loose Index Scan was used on a query that used MIN(), a segmentation fault could occur. (Bug

#16222245)

• An outer join between a regular table and a derived table that is implicitly groups could cause a server

exit. (Bug #16177639)

• If multiple statements were sent in a single request, the audit log plugin logged only the last one. Now it

logs each statement separately. (Bug #16169063)

• For debug builds, an assertion was incorrectly raised for queries executed using eq_ref access and

filesort. (Bug #16164885)

• A prepared statement that used GROUP_CONCAT() and an ORDER BY clause that named multiple

columns could cause the server to exit. (Bug #16075310)

• ORDER BY MATCH ... AGAINST could cause a server exit. (Bug #16073689)

• Creating a FEDERATED table without specifying a connection string caused a server exit. (Bug

#16048546)

• Client programs from MySQL 5.6.4 and up could confuse older servers during the connection process by

using newer protocol features not understood by older servers. (Bug #15965409)

• The mysql.server script exited with an error if the status command was executed with multiple

servers running. (Bug #15852074)

• In some cases, REVOKE could fail to revoke the GRANT OPTION privilege. (Bug #14799187)

• Use of the VALUES() function in the VALUES() clause of an INSERT statement could result in Valgrind

warnings or an unstable server, possibly leading to a server exit. (Bug #14789787)

• The mysql client allocated but did not free a string after reading each line in interactive mode, resulting

in a memory leak. (Bug #14685362)

• Killing a connection while it was in the process of disconnecting could lead to an assertion being raised,

Valgrind warnings, and general unstability. (Bug #14560522)

• INSERT ... ON DUPLICATE KEY UPDATE on a view could cause a server exit. (Bug #14261010)

• Grouping by an outer BLOB column in a subquery caused a server exit. (Bug #13966809, Bug

#14700180)

• The server could exit due to improper handling of the error from an invalid comparison. (Bug #13009341)

• The CMake check for unsigned time_t failed on all platforms. (Bug #11766815)

• mysqladmin debug causes the server to write debug information to the error log. On systems that

supported mallinfo(), the memory-status part of this output was incorrect in 64-bit environments

when mysqld consumed more than 4GB memory.

Now the server uses malloc_info() to obtain memory-status information. malloc_info() does

not report the memory that the glibc malloc() implementation internally allocates using mmap().

However, it does provide the memory usage information in all the memory arenas.

This bug fix also involves a change of output format. The server now writes memory information in XML

format rather than as plain text. Example:

128

MySQL 5.6 Release Notes

Memory status:

<sizes>

</sizes>

</heap>

</malloc>

(Bug #11746658)

• Queries against a view that was created using a CASE operator and a HAVING clause were incorrectly

rejected with ER_VIEW_INVALID (Error 1356). (Bug #69774, Bug #17183462)

• FOUND_ROWS() could return an incorrect value if the preceding query used filesort. (Bug #69119,

Bug #16760474)

References: This issue is a regression of: Bug #68458.

• The optimizer could choose a poor execution plan for queries with ORDER BY ... LIMIT. (Bug

#69013, Bug #16697792)

• When specified in an option file, the plugin-dir client option was ignored. (Bug #68800, Bug

#16680313)

• When only counting events but not timing them, Performance Schema would report MIN_TIMER_WAIT

values as a large number instead of 0. (Bug #68768, Bug #16552425)

• Using range access with an index prefix could produce incorrect results. (Bug #68750, Bug #16540042)

• For debug builds, metadata locking for CREATE TABLE ... SELECT could raise an assertion. (Bug

#68695, Bug #16503173)

• mysqld --help and mysqld --verbose --help performed unnecessary logging. (Bug #68578, Bug

#16442113)

• A new CMake option, WITH_EDITLINE, is provided to indicate whether to use the bundled or system

libedit/editline library. The permitted values are bundled (the default) and system.

WITH_EDITLINE replaces WITH_LIBEDIT, which has been removed. (Bug #68558, Bug #16430208)

• If Loose Index Scan was used to evaluate a query that compared an integer column to an integer

specified as a quoted string (for example, col_name = '1'), the query could return incorrect results.

(Bug #68473, Bug #16394084)

129

MySQL 5.6 Release Notes

• In a MySQL server newer than MySQL 5.5 using a nonupgraded mysql.user table (for which

mysql_upgrade had not been run), statements to set passwords caused a server exit due to a faulty

check for the password_expired column. (Bug #68385, Bug #16339767)

• Indexes on derived tables that were used during the first invocation of a stored procedure were not used

in subsequent invocations. (Bug #68350, Bug #16346367)

• If a function such as AES_DECRYPT() that requires SSL support failed, the error could affect later calls

to functions that require SSL support. (Bug #68340, Bug #16315767)

• For DELETE and UPDATE statements, EXPLAIN displayed NULL in the ref column for some cases

where const is more appropriate. (Bug #68299, Bug #16296268)

• The mysql client incorrectly used latin1 for certain comparisons even if started with a multibyte

default character set, resulting in a client crash. (Bug #68107, Bug #16182919)

• InnoDB does not support full-text parser plugins, but failed to report an error if they were specified. Now

an ER_INNODB_NO_FT_USES_PARSER error is returned. (Bug #62004, Bug #12843070)

• The url columns in the mysql datatbase help tables were too short to hold some of the URLs in

the help content. These columns are now created as type TEXT to accommodate longer URLs. (Bug

#61520, Bug #12671635)

• Two problems adding or subtracting keyword from the current debug system variable setting were

corrected:

• A debug value of 'd' means “all debug macros enabled”. The following sequence left the value in an

incorrect state:

mysql> SET debug = 'd';SELECT @@debug;

+---------+

| @@debug |

+---------+

| d |

+---------+

mysql> SET debug = '+d,M1';SELECT @@debug;

+---------+

| @@debug |

+---------+

| d,M1 |

+---------+

The first SET statement enables all debug macros. The second SET should add the M1 macro to the

current set, which should result in no change because the current set is already “all macros”. Instead,

the second SET reset the current set to only the M1 macro, effectively disabling all others. The server

now correctly leaves debug set to 'd'.

• A debug value of '' means “no debug macros enabled”. The following sequence left the value in an

incorrect state:

mysql> SET debug = 'd,M1';SELECT @@debug;

+---------+

| @@debug |

+---------+

| d,M1 |

+---------+

mysql> SET debug = '-d,M1';SELECT @@debug;

130

MySQL 5.6 Release Notes

+---------+

| @@debug |

+---------+

| d |

+---------+

The first SET statement sets debug to the M1* macro. The second SET should subtract the M1 macro

from the current set, leaving no debug macros enabled. Instead, the second SET reset the current set

to 'd' (all macros enabled). The server now correctly sets debug to ''.

(Bug #58630, Bug #11765644)

• It is now possible to suppress installation of the mysql-test directory after compiling MySQL from

source by invoking CMake with the INSTALL_MYSQLTESTDIR option explicitly set to empty:

cmake . -DINSTALL_MYSQLTESTDIR=

Previously, attempts to do this resulted in an error. (Bug #58615, Bug #11765629)

• On 64-bit OS X systems, CMake used x86 rather than x86_64 when determining the machine type.

(Bug #58462, Bug #11765489)

• IF() function evaluations could produce different results when executed in a prepared versus

nonprepared statement. (Bug #45370, Bug #11753852)

Changes in MySQL 5.6.11 (2013-04-18, General Availability)

A known limitation of this release:

Note

If you have InnoDB tables with full-text search indexes and you are upgrading from

MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server

will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.

As a workaround, remove full-text search indexes prior to upgrading and rebuild full-

text search indexes after the upgrade is completed.

• Deprecation and Removal Notes

• RPM Notes

• Functionality Added or Changed

• Bugs Fixed

Deprecation and Removal Notes

• The only supported value for the innodb_mirrored_log_groups system variable is 1, so this

variable is now deprecated. Setting it to 1 at startup results in a warning. Setting it to a value other than

1 at startup results in an error and the server exits. This variable will be removed in a future release. (WL

#6808)

RPM Notes

• It was not possible to upgrade a community RPM to a commercial RPM using rpm -uvh or yum

localupdate. To deal with this, the RPM spec file has been updated in MySQL 5.6.11, which has the

following consequences:

131

MySQL 5.6 Release Notes

• For a non-upgrade installation (no existing MySQL version installed), it possible to install MySQL using

yum.

• For upgrades, it is necessary to clean up any earlier MySQL installations. In effect, the update is

performed by removing the old installations and installing the new one.

Additional details follow.

For a non-upgrade installation of MySQL 5.6.11, it is possible to install using yum:

shell> yum install MySQL-server-NEWVERSION.glibc23.i386.rpm

For upgrades to MySQL 5.6.11, the upgrade is performed by removing the old installation and installing

the new one. To do this, use the following procedure:

1. Remove the existing 5.6.X installation. OLDVERSION is the version to remove.

shell> rpm -e MySQL-server-OLDVERSION.glibc23.i386.rpm

Repeat this step for all installed MySQL RPMs.

2. Install the new version. NEWVERSION is the version to install.

shell> rpm -ivh MySQL-server-NEWVERSION.glibc23.i386.rpm

Alternatively, the removal and installation can be done using yum:

shell> yum remove MySQL-server-OLDVERSION.glibc23.i386.rpm

shell> yum install MySQL-server-NEWVERSION.glibc23.i386.rpm

(Bug #16445097, Bug #16445125, Bug #16587285)

Functionality Added or Changed

• Replication: The functions GTID_SUBTRACT() and GTID_SUBSET() were formerly available in

libmysqld only when it was built with replication support. Now these functions are always available

when using this library, regardless of how it was built.

• MySQL no longer uses the default OpenSSL compression. (Bug #16235681)

• There is now a distinct error code (ER_MUST_CHANGE_PASSWORD_LOGIN) for the error sent by the

server to a client authenticating with an expired password. (Bug #16102943)

• mysql_config_editor now supports --port and --socket options for specifying TCP/IP port

number and Unix socket file name. (Bug #15851247)

• mysqlcheck has a new --skip-database option. The option value is the name of a database (case

sensitive) for which checks should be skipped.

mysql_upgrade adds this option to mysqlcheck commands that it generates to upgrade the system

tables in the mysql database before tables in other databases: It upgrades the mysql database, then all

databases except the mysql database. This avoids problems that can occur if user tables are upgraded

before the system tables. (Bug #14697538, Bug #68163, Bug #16216384)

Bugs Fixed

• Incompatible Change; Partitioning: Changes in the KEY partitioning hashing functions used with

numeric, date and time, ENUM, and SET columns in MySQL 5.5 makes tables using partitioning or

132

MySQL 5.6 Release Notes

subpartitioning by KEY on any of the affected column types and created on a MySQL 5.5 or later server

incompatible with a MySQL 5.1 server. This is because the partition IDs as calculated by a MySQL 5.5

or later server almost certainly differ from those calculated by a MySQL 5.1 server for the same table

definition and data as a result of the changes in these functions.

The principal changes in the KEY partitioning implementation in MySQL 5.5 resulting in this issue were

as follows: 1. The hash function used for numeric and date and time columns changed from binary to

character-based. 2. The base used for hashing of ENUM and SET columns changed from latin1 ci

characters to binary.

The fix involves adding the capability in MySQL 5.5 and later to choose which type of hashing to use

for KEY partitioning, which is implemented with a new ALGORITHM extension to the PARTITION BY

KEY option for CREATE TABLE and ALTER TABLE. Specifying PARTITION BY KEY ALGORITHM=1

([columns]) causes the server to use the hashing functions as implemented in MySQL 5.1; using

ALGORITHM=2 causes the server to use the hashing functions from MySQL 5.5 and later. ALGORITHM=2

is the default. Using the appropriate value for ALGORITHM, you can perform any of the following tasks:

• Create KEY partitioned tables in MySQL 5.5 and later that are compatible with MySQL 5.1, using

CREATE TABLE ... PARTITION BY KEY ALGORITHM=1 (...).

• Downgrade KEY partitioned tables that were created in MySQL 5.5 or later to become compatible with

MySQL 5.1, using ALTER TABLE ... PARTITION BY KEY ALGORITHM=1 (...).

• Upgrade KEY partitioned tables originally created in MySQL 5.1 to use hashing as in MySQL 5.5 and

later, using ALTER TABLE ... PARTITION BY KEY ALGORITHM=2 (...).

Important: After such tables are upgraded, they cannot be used any longer with MySQL 5.1 unless

they are first downgraded again using ALTER TABLE ... PARTITION BY KEY ALGORITHM=1

(...) on a MySQL server supporting this option.

This syntax is not backward compatible, and causes errors in older versions of the MySQL server.

When generating CREATE TABLE ... PARTITION BY KEY statements, mysqldump brackets any

occurrence of ALGORITHM=1 or ALGORITHM=2 in conditional comments such that it is ignored by a

MySQL server whose version is not at least 5.5.31. An additional consideration for upgrades is that

MySQL 5.6 servers prior to MySQL 5.6.11 do not ignore the ALGORITHM option in such statements when

generated by a MySQL 5.5 server, due to the that the conditional comments refer to version 5.5.31; in

this case, you must edit the dump manually and remove or comment out the option wherever it occurs

before attempting to load it into a MySQL 5.6.10 or earlier MySQL 5.6 server. This is not an issue for

dumps generated by MySQL 5.6.11 or later version of mysqldump, where the version used in such

comments is 5.6.11. For more information, see ALTER TABLE Partition Operations.

As part of this fix, a spurious assertion by InnoDB that a deleted row had previously been read, causing

the server to assert on delete of a row that the row was in the wrong partition, was also removed. (Bug

#14521864, Bug #66462, Bug #16093958, Bug #16274455)

References: See also: Bug #11759782.

• Incompatible Change: For debug builds, creating an InnoDB table in strict SQL mode that violated the

maximum key length limit caused the server to exit.

A behavior change in consequence of this bug fix: In strict SQL mode, a key length limit violation now

results in a error (and the table is not created), rather than a warning and truncation of the key to the

maximum key length. This applies to all storage engines. (Bug #16035659)

133

MySQL 5.6 Release Notes

• Important Change; Replication

Important

This fix was reverted in MySQL 5.6.12. See Changes in MySQL 5.6.12

(2013-06-03, General Availability).

Executing a statement that performs an implicit commit but whose changes are not logged when

gtid_next is set to any value other than AUTOMATIC is not permitted. Now in such cases, the

statement fails with an error. This includes the statements in the following list:

• CHANGE MASTER TO

• START SLAVE

• STOP SLAVE

• REPAIR TABLE

• OPTIMIZE TABLE

• ANALYZE TABLE

• CHECK TABLE

• CREATE SERVER

• ALTER SERVER

• DROP SERVER

• CACHE INDEX

• LOAD INDEX INTO CACHE

• FLUSH

• RESET

(Bug #16062608)

References: See also: Bug #16484323.

• Important Change; Replication: The version number reported by mysqlbinlog --version has been

increased to 3.4. (Bug #15894381, Bug #67643)

• Important Note; Replication: Using row-based logging to replicate from a table to a same-named view

led to a failure on the slave. Now, when using row-based logging, the target object type is checked prior

to performing any DML, and an error is given if the target on the slave is not actually a table.

Note

It remains possible to replicate from a table to a same-named view using

statement-based logging.

(Bug #11752707, Bug #43975)

134

MySQL 5.6 Release Notes

• Performance; InnoDB: Switching the MySQL table used by the InnoDB memcached interface (using

the @@ notation), was made more efficient, by reading cached information about the cache policy to use

for each table. This optimization lets you frequently switch between tables during a session that uses the

memcached interface, without incurring I/O overhead from examining table metadata each time. (Bug

#16206654)

• Performance; InnoDB: Performance was improved for operations on tables with many rows that were

deleted but not yet purged. The speedup applies mainly to workloads that perform bulk deletes, or

updates to the primary key columns, and where the system is busy enough to experience purge lag.

(Bug #16138582, Bug #68069)

• Performance; InnoDB: The DROP TABLE statement for a table using compression could be slower than

necessary, causing a stall for several seconds. MySQL was unnecessarily decompressing pages in the

buffer pool related to the table as part of the DROP operation. (Bug #16067973)

• Performance; InnoDB: The I/O routines used when the AIO subsystem were made more efficient, to

merge consecutive I/O requests into a single operation. This fix solves a performance issue introduced

during the 5.6 development cycle. (Bug #16043841, Bug #67973)

• InnoDB: When ADD PRIMARY KEY columns are reordered in an ALTER TABLE statement (for

example: ALTER TABLE t1 ADD PRIMARY KEY(a,b), CHANGE a a INT AFTER b), the log apply

for UPDATE operations failed to find rows. (Bug #16586355)

• InnoDB: ALTER TABLE operations on InnoDB tables that added a PRIMARY KEY using a column prefix

could produce an incorrect result. (Bug #16544336)

• InnoDB: For ALTER TABLE operations on InnoDB tables that required a table-copying operation,

other transactions on the table might fail during the copy. However, if such a transaction issued a partial

rollback, the rollback was treated as a full rollback. (Bug #16544143)

• InnoDB: When parsing a delimited search string such as “abc-def” in a full-text search, InnoDB now

uses the same word delimiters as MyISAM. (Bug #16419661)

• InnoDB: Naming inconsistencies were addressed for InnoDB PERFORMANCE_SCHEMA key declarations.

(Bug #16414044)

• InnoDB: Status values in the innodb_ft_config table would not update. The innodb_ft_config

is intended for internal configuration and should not be used for statistical information purposes.

To avoid confusion, column values that are intended for internal use have been removed from the

innodb_ft_config table. This fix also removes the innodb_ft_config table and other internal full

text search-related tables that were unintentionally exposed. (Bug #16409494, Bug #68502)

• InnoDB: Crash recovery failed with a !recv_no_log_write assertion when reading a page. (Bug

#16405422)

• InnoDB: This fix disables a condition for extra splitting of clustered index leaf pages, on compressed

tables. Extra page splitting was only done to reserve space for future updates, so that future page splits

could be avoided. (Bug #16401801)

• InnoDB: For InnoDB tables, if a PRIMARY KEY on a VARCHAR column (or prefix) was empty, index

page compression could fail. (Bug #16400920)

• InnoDB: The InnoDB page-splitting algorithm could recurse excessively. (Bug #16345265)

• InnoDB: Improper testing of compatibility between the referencing and referenced during ALTER

TABLE ... ADD FOREIGN key could cause a server exit. (Bug #16330036)

• InnoDB: Importing a tablespace with the configuration file present would not import the data file. This

problem would occur when all pages are not flushed from the buffer pool after a table is altered using the

135

MySQL 5.6 Release Notes

copy and rename approach. This fix ensures that all pages are flushed from the buffer pool when a table

is altered using the copy and rename approach. (Bug #16318052)

• InnoDB: Rollback did not include changes made to temporary tables by read-only transactions. (Bug

#16310467)

• InnoDB: When using ALTER TABLE to set an AUTO_INCREMENT column value to a user-

specified value, InnoDB would set the AUTO_INCREMENT value to the user-specified value

even when the AUTO_INCREMENT value is greater than the user-specified value. This fix

ensures that the AUTO_INCREMENT value is set to the maximum of the user-specified value and

MAX(auto_increment_column)+1, which is the expected behaviour. (Bug #16310273)

• InnoDB: RENAME TABLE would result in a hang due to a MySQL mutex acquisition deadlock. (Bug

#16305265)

• InnoDB: For debug builds, InnoDB status exporting was subject to a race condition that could cause a

server exit. (Bug #16292043)

• InnoDB: With innodb_api_enable_mdl=OFF, an ALTER TABLE operation on an InnoDB table that

required a table copy could cause a server exit. (Bug #16287411)

• InnoDB: An assertion failure would occur in heap->magic_n == MEM_BLOCK_MAGIC_N due to a

race condition that appeared when row_merge_read_clustered_index() returned an error. (Bug

#16275237)

• InnoDB: InnoDB now aborts execution on Windows by calling the abort() function directly, as it does

on other platforms. (Bug #16263506)

• InnoDB: This fix removes an unnecessary debug assertion related to page_hash locks which only

affects debug builds. The debug assertion is no longer valid and should have been removed when

hash_lock array was introduced in MySQL 5.6. (Bug #16263167)

• InnoDB: Internal read operations could be misclassified as synchronous when they were actually

asynchronous. When the I/O requests returned sooner than expected, threads could be scheduled

inefficiently. This issue mainly affected read-ahead requests, and thus had relatively little impact on I/O

performed by user queries. (Bug #16249505, Bug #68197)

• InnoDB: The lock_validate function, which is only present in debug builds, acquired and released

mutexes to avoid hogging them. This behavior introduced a window wherein changes to the hash table

could occur while code traversed the same set of data. This fix updates lock_validate logic to collect

all records for which locks must be validated, releases mutexes, and runs a loop to validate record locks.

(Bug #16235056)

• InnoDB: ALTER TABLE functions would perform a check to see if InnoDB is in read-only mode

(srv_read_only_mode=true). If InnoDB was in read-only mode, the check would return a successful

status and do nothing else. This fix replaces srv_read_only_mode check conditions with debug

assertions. (Bug #16227539)

• InnoDB: When the InnoDB buffer pool is almost filled with 4KB compressed pages, inserting into 16KB

compact tables would cause 8KB pages_free to increase, which could potentially slow or stall inserts.

(Bug #16223169)

• InnoDB: This fix updates InnoDB code in ha_innodb.cc and handler0alter.cc to use

TABLE::key_info instead of both TABLE::key_info and TABLE_SHARE::key_info. (Bug

#16215361)

• InnoDB: When InnoDB locking code was revised, a call to register lock waits was inadvertently

removed. This fix adds the call back to the InnoDB locking code. (Bug #16208201)

136

MySQL 5.6 Release Notes

• InnoDB: If the MySQL server halted at a precise moment when a purge operation was being applied

from the change buffer, the operation could be incorrectly performed again during the next restart. A

workaround was to set the configuration option innodb_change_buffering=changes, to turn off

change buffering for purge operations. (Bug #16183892, Bug #14636528)

• InnoDB: The InnoDB memcached plugin could encounter a serious error under a heavy load, such as

produced by benchmark runs. (Bug #16182660, Bug #68096)

• InnoDB: A direct call to the trx_start_if_not_started_xa_low() function would cause a debug

assertion. (Bug #16178995)

• InnoDB: In the case of LOCK WAIT for an insert in a foreign key table, InnoDB could report a false

dictionary-changed error and cause the insert to fail rather than being retried. (Bug #16174255)

• InnoDB: An in-place ALTER TABLE on an InnoDB table could fail to delete the statistics for the old

primary key from the mysql.innodb_index_stats table. (Bug #16170451)

• InnoDB: In some cases, deadlock detection did not work, resulting in sessions hanging waiting for a

lock-wait timeout. (Bug #16169638)

• InnoDB: Arithmetic underflow during page compression for CREATE TABLE on an InnoDB table could

cause a server exit. (Bug #16089381)

• InnoDB: For debug builds, online ALTER TABLE operations for InnoDB tables could cause a server exit

during table rebuilding. (Bug #16063835)

• InnoDB: In some cases, the InnoDB purge coordinator did not use all available purge threads, resulting

in suboptimal purge activity. (Bug #16037372)

• InnoDB: On systems that cannot handle unaligned memory access, depending on the stack frame

alignment, a SIGBUS error could occur during startup. This issue was observed on Solaris 64-bit

systems. (Bug #16021177)

• InnoDB: ALTER TABLE for InnoDB tables was not fully atomic. (Bug #15989081)

• InnoDB: When innodb_mirrored_log_groups was set to a value other than the default 1, the

MySQL server encountered a serious error during startup while loading the InnoDB memcached plugin.

In earlier releases, the server would refuse to start (but not display an error) when this setting was

changed. This fix cleans up the error handling for unsupported values of this configuration option. (Bug

#15907954, Bug #67670)

• InnoDB: The innodb_sync_array_size variable was incorrectly allowed to be configured at runtime.

As documented, innodb_sync_array_size must be configured when the MySQL instance is starting

up, and cannot be changed afterward. This fix changes innodb_sync_array_size to a non-dynamic

variable, as intended. (Bug #14629979)

• InnoDB: An error at the filesystem level, such as too many open files, could cause an unhandled error

during an ALTER TABLE operation. The error could be accompanied by Valgrind warnings, and by this

assertion message:

Assertion `! is_set()' failed.

mysqld got signal 6 ;

(Bug #14628410, Bug #16000909)

• InnoDB: The server could exit during an attempt by InnoDB to reorganize or compress a compressed

secondary index page. (Bug #14606334)

137

MySQL 5.6 Release Notes

• InnoDB: A DML operation performed while a RENAME TABLE operation waits for pending I/O operations

on the tablespace to complete would result in a deadlock. (Bug #14556349)

• InnoDB: A RENAME TABLE statement could stall for several minutes before timing out. This issue could

occurred for a table using compression, with change buffering enabled. (Bug #14556349)

• InnoDB: If the server was started with the skip-innodb option, or InnoDB otherwise failed to start,

query any of these Information Schema tables would cause a severe error:

• INNODB_BUFFER_PAGE

• INNODB_BUFFER_PAGE_LRU

• INNODB_BUFFER_POOL_STATS

(Bug #14144290)

• InnoDB: Online DDL had a restriction that prevented renaming a column and adding a foreign key

involving that column in a single ALTER TABLE statement. Now, this combination of operations is

allowed in a single statement. (Bug #14105491)

• InnoDB: When printing out long semaphore wait diagnostics, sync_array_cell_print() ran into

a segmentation violation (SEGV) caused by a race condition. This fix addresses the race condition by

allowing the cell to be freed while it is being printed. (Bug #13997024)

• InnoDB: The value of the innodb_version variable was not updated consistently for all server

releases for the InnoDB Plugin in MySQL 5.1, and the integrated InnoDB component in MySQL 5.5, 5.6,

and higher. Since InnoDB and MySQL Server development cycles are fully integrated and synchronized,

now the value returned by the innodb_version variable is the same as for the version variable. (Bug

#13463493, Bug #63435)

• InnoDB: Attempting to replace the default InnoDB full-text search (FTS) stopword list by creating an

InnoDB table with the same structure as INFORMATION_SCHEMA.INNODB_FT_DEFAULT_STOPWORD

would result in an error. SHOW CREATE TABLE revealed that the new InnoDB table was created with

CHARSET=utf8. The InnoDB FTS stopword table validity check only supported latin1. This fix extends

the validity check for all supported character sets. (Bug #68450, Bug #16373868)

• InnoDB: This fix removes left-over prototype code for srv_parse_log_group_home_dirs, and

related header comments. (Bug #68133, Bug #16198764)

• InnoDB: Killing a query caused an InnoDB assertion failure when the same table (cursor) instance

was used again. This is the result of a regression error introduced by the fix for Bug#14704286. The fix

introduced a check to handle kill signals for long running queries but the cursor was not restored to the

proper state. (Bug #68051, Bug #16088883)

• InnoDB: On startup, InnoDB reported a message on 64-bit Linux and 64-bit Windows systems stating

that the CPU does not support crc32 instructions. On Windows, InnoDB does not use crc32 instructions

even if supported by the CPU. This fix revises the wording of the message and implements a check for

availability of crc32 instructions. (Bug #68035, Bug #16075806)

• InnoDB: The length of internally generated foreign key names was not checked. If internally generated

foreign key names were over the 64 character limit, this resulted in invalid DDL from SHOW CREATE

TABLE. This fix checks the length of internally generated foreign key names and reports an error

message if the limit is exceeded. (Bug #44541, Bug #11753153)

• Partitioning: ALGORITHM = INPLACE, which was disallowed in MySQL 5.6.10 for DDL statements

operating on partitioned tables, can once again be used with such statements. (Bug #16216513)

138

MySQL 5.6 Release Notes

References: See also: Bug #14760210.

• Partitioning: A query on a table partitioned by range and using TO_DAYS() as a partitioing function

always included the first partition of the table when pruning. This happened regardless of the range

employed in the BETWEEN clause of such a query. (Bug #15843818, Bug #49754)

• Partitioning: Execution of ALTER TABLE ... DROP PARTITION against a view caused the server to

crash, rather than fail with an error as expected. (Bug #14653504)

• Partitioning: A query result was not sorted if both DISTINCT and ORDER BY were used and the

underlying table was partitioned. (Bug #14058167)

• Partitioning: Inserting any number of rows into an ARCHIVE table that used more than 1000 partitions

and then attempting to drop the table caused the MySQL Server to fail. (Bug #13819630, Bug #64580)

• Replication: When using GTIDs and binary log auto-positioning, the master had to scan all binary logs

whenever the slave reconnected (due to reasons such as I/O thread failure or a change of master)

before it could send any events to slave. Now, the master starts from the oldest binary log that contains

any GTID not found on the slave. (Bug #16340322, Bug #68386)

• Replication: When the server version of the master was greater than or equal to 10, replication to a

slave having a lower server version failed. (Bug #16237051, Bug #68187)

• Replication: When replicating to a MySQL 5.6 master to an older slave, Error 1193

(ER_UNKNOWN_SYSTEM_VARIABLE) was logged with a message such as Unknown system

variable 'SERVER_UUID' on master, maybe it is a *VERY OLD MASTER*. This message

has been improved to include more information, similar to this one: Unknown system variable

'SERVER_UUID' on master. A probable cause is that the variable is not

supported on the master (version: 5.5.31), even though it is on the slave

(version: 5.6.11). (Bug #16216404, Bug #68164)

• Replication: When MTS is on and transactions are being applied, the slave coordinator would hang

when encountering a checksum error on a transaction event. This was due to a deadlock situation in

which the coordinator assumed a normal stop while a worker waited for the coordinator to dispatch

more events. For debug builds, the problem appeared as an assertion failure, which was due to the

coordinator not setting thd->is_error() when encountering an error. (Bug #16210351)

• Replication: A zero-length name for a user variable (such as @``) was incorrectly considered to be a

sign of data or network corruption when reading from the binary log. (Bug #16200555, Bug #68135)

• Replication: mysqlbinlog can connect to a remote server and read its binary logs. In MySQL 5.6 and

later, this tool can also wait for the server to generate and send additional events, in practice behaving

like a slave connecting to a master. In cases where the server sent a heartbeat, mysqlbinlog was

unable to handle it properly. As a consequence, mysqlbinlog failed at this point, without reading any

more events from the server. To fix this problem, mysqlbinlog now ignores any binary log events of

type HEARTBEAT_LOG_EVENT that it receives. (Bug #16104206)

• Replication: STOP SLAVE could cause a deadlock when issued concurrently with a statement

such as SHOW STATUS that retrieved the values for one or more of the status variables

Slave_retried_transactions, Slave_heartbeat_period, Slave_received_heartbeats,

Slave_last_heartbeat, or Slave_running. (Bug #16088188, Bug #67545)

References: See also: Bug #16088114.

• Replication: Backtick (`) characters were not always handled correctly in internally generated SQL

statements, which could sometimes lead to errors on the slave. (Bug #16084594, Bug #68045)

139

MySQL 5.6 Release Notes

References: This issue is a regression of: Bug #14548159, Bug #66550.

• Replication: In order to provision or to restore a server using GTIDs, it is possible to set gtid_purged

to a given GTID set listing the transactions that were imported. This operation requires that the global

gtid_executed and gtid_purged server system variables are empty. (This is done in order to avoid

the possibility of overriding server-generated GTIDs.)

The error message GTID_PURGED can only be set when GTID_EXECUTED is empty that

was raised when this requirement was not met could be confusing or misleading because it did not

specify the scope of the affected variables. To prevent this from happening, error messages that refer

to variables relating to GTIDs now specify the scope of any such variables when they do so. (Bug

#16084426, Bug #68038)

• Replication: The session-level value for gtid_next was incorrectly reset on the slave for all rollbacks,

which meant that GTIDs could be lost for multi-statement transactions, causing the slave to stop with an

ER_GTID_NEXT_TYPE_UNDEFINED_GROUP error. Now this is done only when a complete transaction is

being rolled back, or when autocommit is enabled. (Bug #16084206)

• Replication: Using the --replicate-* options (see Replica Server Options and Variables) could in

some cases lead to a memory leak on the slave. (Bug #16056813, Bug #67983)

• Replication: In some cases, when the slave could not recognize the server version of the master, this

could cause the slave to fail. (Bug #16056365)

• Replication: In certain cases, the dump thread could send a heartbeat out of synchronisation with

format description events. One of the effects of this issue what that, after provisioning a new server from

a backup data directory and setting --gtid-mode=ON and enabling autopositioning (see CHANGE

MASTER TO Statement), replication failed to start, with the error Read invalid event from

master.... The same problem could also cause GTID-based replication to fail due to skipped events

following a unplanned shutdown of the master. (Bug #16051857)

• Replication: Table IDs used in replication were defined as type ulong on the master and uint on the

slave. In addition, the maximum value for table IDs in binary log events is 6 bytes (281474976710655).

This combination of factors led to the following issues:

• Data could be lost on the slave when a table was assigned an ID greater than uint.

• Table IDs greater than 281474976710655 were written to the binary log as 281474976710655.

• This led to a stopped slave when the slave encountered two tables having the same table ID.

To fix these problems, IDs are now defined by both master and slave as type ulonglong but

constrained to a range of 0 to 281474976710655, restarting from 0 when it exceeds this value. (Bug

#14801955, Bug #67352)

• Replication: Internal objects used for relay log information were only partially deleted before freeing

their memory. (Bug #14677824)

• Replication: It was possible in certain cases—immediately after detecting an EOF in the dump thread

read event loop, and before deciding whether to change to a new binary log file—for new events to be

written to the binary log before this decision was made. If log rotation occurred at this time, any events

that occurred following EOF detection were dropped, resulting in loss of data. Now in such cases, steps

are taken to make sure that all events are processed before allowing the log rotation to take place. (Bug

#13545447, Bug #67929)

References: See also: Bug #16016886.

140

MySQL 5.6 Release Notes

• Replication: If the disk becomes full while writing to the binary log, the server hangs until space is freed

up manually. It was possible after this was done for the MySQL server to fail, due to an internal status

value being set when not needed. Now in such cases, rather than trying to set this status, a warning is

written in the error log instead. (Bug #11753923, Bug #45449)

• Microsoft Windows: A server started with --shared-memory to support shared-memory connections

could crash when receiving requests from multiple threads. (Bug #13934876)

• Solaris: mysql_install_db did not work in Solaris 10 sparse root zones. (Bug #68117, Bug

#16197860)

• InnoDB now reports row and table locks to the thread pool plugin. Deadlocks within a thread group

could occur otherwise. (Bug #16448639)

• Failure to handle a full-text search wildcard properly could cause the server to exit. (Bug #16446108)

• SHOW ENGINE PERFORMANCE_SCHEMA STATUS could report incorrect memory-allocation values when

the correct values exceeded 4GB. (Bug #16414644)

• The server could exit if a prepared statement attempted to create a table using the name of an existing

view while an SQL handler was opened. (Bug #16385711)

• Performance Schema statement tokenization overhead was reduced. (Bug #16382260)

• A long database name in a GRANT statement could cause the server to exit. (Bug #16372927)

• On Linux, a race condition involving epoll() could cause the thread pool plugin to miss events. This

was most likely on systems with greater than 16 cores. (Bug #16367483)

• Some aggregate queries attempted to allocate excessive memory. (Bug #16343992)

• For debug builds, an assertion could be raised if a statement failed with autocommit enabled just before

an XA START statement was issued. (Bug #16341673)

• Very small join_buffer_size values could cause an assertion to be raised. (Bug #16328373)

• The BUILD-CMAKE file in MySQL distributions was updated with the correct URL for CMake information.

(Bug #16328024)

• The optimizer's attempt to remove redundant subquery clauses raised an assertion when executing a

prepared statement with a subquery in the ON clause of a join in a subquery. (Bug #16318585)

References: This issue is a regression of: Bug #15875919.

• Incorrect results were returned if a query contained a subquery in an IN clause which contained an XOR

operation in the WHERE clause. (Bug #16311231)

• A Valgrind failure could occur if a CREATE USER statement was logged to the general query log and the

old_passwords system variable was set to 2. (Bug #16300620)

• For debug builds, checking of password constraints could raise an assertion for statements that updated

passwords. (Bug #16289303)

• Conversion of numeric values to BIT could yield unexpected results. (Bug #16271540)

• Fixed warnings when compiling with XCode 4.6. Fixed warnings when compiling when the

_XOPEN_SOURCE or isoctal macro was already defined in the environment. (Bug #16265300, Bug

#60911, Bug #12407384)

141

MySQL 5.6 Release Notes

• In the range optimizer, an index merge failure could cause a server exit. (Bug #16241773)

• For upgrade operations, RPM packages produced unnecessary errors about being unable to access

.err files. (Bug #16235828)

• Queries using range predicates that were evaluated using the LooseScan semijoin strategy could return

duplicate rows. (Bug #16221623)

References: This issue is a regression of: Bug #14728469.

• Certain legal HAVING clauses were rejected as invalid. (Bug #16221433)

• yaSSL did not perform proper padding checks, but instead examined only the last byte of cleartext and

used it to determine how many bytes to remove. (Bug #16218104)

• The Performance Schema could return incorrect values for the PROCESSLIST_INFO column of the

threads table. (Bug #16215165)

• A full-text query using Boolean mode could return zero results in some cases where the search term was

a quoted phrase:

• If the quoted phrase was preceded by a + sign. For example, this combination of a Boolean + operator

and a phrase would return zero results:

WHERE MATCH(content) AGAINST('+"required term due to plus sign"' IN BOOLEAN MODE)

• If the quoted phrase contained any stopwords. For example, the stopword "the" inside the phrase

caused the query to return zero results:

WHERE MATCH(content) AGAINST('"stopword inside the phrase"' IN BOOLEAN MODE)

(Bug #16206253, Bug #68150)

• mysql_config --libs displayed incorrect output. (Bug #16200717)

• Invocation of the range optimizer for a NULL select caused the server to exit. (Bug #16192219)

• If, in a SELECT, the HAVING clause contained a function call which itself contained an alias to a selected

expression, the server could sometimes exit. (Bug #16165981)

• For debug builds, the server could exit due to incorrect calculation of applicable indexes for a join that

involved const tables. (Bug #16165832)

• A bug in range optimization sometimes led to incorrect condition calculation for index merge union. This

could lead to missing rows. (Bug #16164031, Bug #68194, Bug #16229746)

• For a CREATE TABLE (... col_name TIMESTAMP DEFAULT CURRENT_TIMESTAMP ...) ...

SELECT statement for which the SELECT did not provide a value for the TIMESTAMP column, that

column was set to '0000-00-00 00:00:00', not the current timestamp. (Bug #16163936)

• Using GROUP BY WITH ROLLUP in a prepared statement could cause the server to exit. (Bug

#16163596)

• With the thread pool plugin enabled, large numbers of connections could lead to a Valgrind panic or

failure of clients to be able to connect. (Bug #16088658, Bug #16196591)

• Performance Schema instrumentation was missing for slave worker threads. (Bug #16083949)

142

MySQL 5.6 Release Notes

• The server executed EXPLAIN FORMAT=JSON for some malformed queries improperly. (Bug

#16078557)

• With statement-based binary logging, dropping a TEMPORARY InnoDB table could cause a segmentation

fault. (Bug #16076275)

• Setting the slave_rows_search_algorithms system variable to an inappropriate value could cause

the server to exit. (Bug #16074161)

• SET PASSWORD and GRANT ... IDENTIFIED BY have no effect on the password of a user who

is authenticated using an authentication plugin that accesses passwords stored externally to the

mysql.user table. But attempts to change the password of such a user produced no warning, leading

to the impression that the password had been changed when it was not. Now MySQL issues an

ER_SET_PASSWORD_AUTH_PLUGIN warning to indicate that the attempt was ignored. (Bug #16072004)

• Directory name manipulation could result in stack overflow on OS X and Windows. (Bug #16066243)

• The initial test database contained a dummy.bak file that prevented DROP DATABASE from working.

This file is no longer included. Also, a db.opt file is now included that contains these lines:

default-character-set=latin1

default-collation=latin1_swedish_ci

(Bug #16062056)

• Issuing a PREPARE statement using certain combinations of stored functions and user variables caused

the server to exit. (Bug #16056537)

• Setting a system variable to DEFAULT could cause the server to exit. (Bug #16044655)

• For debug builds, if the server was started with binary logging disabled, executing SHOW RELAYLOG

EVENTS from within a stored procedure raised an assertion. (Bug #16043173)

• The query parser leaked memory for some syntax errors. (Bug #16040022)

• During shutdown, the server could attempt to lock an uninitialized mutex. (Bug #16016493)

• The --default-authentication-plugin option permitted invalid plugin values, and did not always

set the old_passwords system variable to a value appropriate for the named plugin. (Bug #16014394)

• The --character-set-server option could set connection character set system variables to values

such as ucs2 that are not permitted. (Bug #15985752, Bug #23303391)

• Under some circumstances, mysql --secure-auth permitted passwords to be sent to the server

using the old (pre-4.1) hashing format. (Bug #15977433)

• When a partition is missing, code in ha_innodb.cc would retry 10 times and sleep for a microsecond

each time while holding LOCK_open. The retry logic for partitioned tables was introduced as a fix for

Bug#33349 but did not include a test case to validate it. This fix removes the retry logic for partitioned

tables. If the problem reported in Bug#33349 reappears, a different solution will be explored. (Bug

#15973904)

• Joins of exactly 32 tables and containing a HAVING clause returned an empty result. (Bug #15972635)

• A mysys library string-formatting routine could mishandle width specifiers. (Bug #15960005)

• Table creation operations added entries to the file_instances Performance Schema table, but these

were not always removed for table drop operations. (Bug #15927620)

143

MySQL 5.6 Release Notes

• With index condition pushdown enabled, queries for which the pushed-down condition contained no

columns in the used index could be slow. (Bug #15896009)

• A query with an EXISTS/IN/ALL/ANY subquery with an ORDER BY clause ordering by an outer column

of type BLOB that is not in the select list caused an assertion to fire. (Bug #15875919)

References: See also: Bug #14728142.

• In special cases, the optimizer did not consider indexes that were applicable to query processing,

resulting in potentially suboptimal execution and incorrect EXPLAIN output. (Bug #15849135, Bug

#16094171)

• Creating an InnoDB table with a FULLTEXT index could encounter a serious error if the table name

contained nonalphanumeric characters. (Bug #14835178, Bug #16036699)

• Enabling the query cache during high client contention could cause the server to exit. (Bug #14727815)

• The MSI Installer installed MySQL in “per-user” mode, which could result in conflicts or failure to detect

an existing installation if two users installed MySQL on the same machine. Now the MSI Installer uses

“per-machine” installation mode. (Bug #14711808)

• The server sometimes failed to respect MAX_CONNECTIONS_PER_HOUR limits on user connections. (Bug

#14627287)

• The optimizer could return incorrect results after transforming an IN subquery with aggregate functions

to an EXISTS subquery. (Bug #14586710)

• SET PASSWORD for anonymous users did not work correctly. (Bug #14561102)

• When a client program loses the connection to the MySQL server or if the server begins a shutdown

after the client has executed mysql_stmt_prepare(), the next mysql_stmt_prepare() returns an

error (as expected) but subsequent mysql_stmt_execute() calls crash the client. (Bug #14553380)

• Previously, if multiple --login-path options were given, mysql_config_editor ignored all but the

last one. Now multiple --login-path options result in an error. (Bug #14551712)

• SHOW COLUMNS on a view defined as a UNION of Geometry columns could cause the server to exit.

(Bug #14362617)

• The sha256_password_private_key_path and sha256_password_public_key_path system

variables indicate key files for the sha256_password authentication plugin, but the server failed to

properly check whether the key files were valid. Now in the event that either key file is invalid, the server

logs an error and exits. (Bug #14360513)

• SET var_name = VALUES(col_name) could cause the server to exit. This syntax is now prohibited

because in SET context there is no column name and the statement returns ER_BAD_FIELD_ERROR.

(Bug #14211565)

• The COM_CHANGE_USER command in the client/server protocol did not properly use the character set

number in the command packet, leading to incorrect character set conversion of other values in the

packet. (Bug #14163155)

• Invoking the FORMAT() function with a locale and a very large number could cause the server to exit.

(Bug #14040155)

• yaSSL rejected some valid server SSL certificates. (Bug #13777928)

• Certain plugin-related conditions can make a user account unusable:

144

MySQL 5.6 Release Notes

• The account requires an authentication plugin that is not loaded.

• The account requires the sha256_password authentication plugin but the server was started with

neither SSL nor RSA enabled as required by this plugin.

The server now checks those conditions by default and produces warnings for unusable accounts. This

checking slows down server initialization and FLUSH PRIVILEGES, so it is made optional by means of

the new validate_user_plugins system variable. This variable is enabled by default, but if you do

not require the additional checking, you can disable it at startup to avoid the performance decrement.

(Bug #13010061, Bug #14506305)

• Passing an unknown time zone specification to CONVERT_TZ() resulted in a memory leak. (Bug

#12347040)

• The obsolete linuxthreads.txt and glibc-2.2.5.patch files in the Docs directory of MySQL

distributions have been removed. (Bug #11766326)

• mysql_install_db did not escape '_' in the host name for statements written to the grant tables.

(Bug #11746817)

• With explicit_defaults_for_timestamp enabled, inserting NULL into a TIMESTAMP NOT NULL

column now produces an error (as it already did for other NOT NULL data types), instead of inserting the

current timestamp. (Bug #68472, Bug #16394472)

• Handling of SQL_CALC_FOUND_ROWS in combination with ORDER BY and LIMIT could lead to incorrect

results for FOUND_ROWS(). (Bug #68458, Bug #16383173)

• If INET6_NTOA() or INET6_ATON() returned NULL for a row in a result set, following rows also

returned NULL. (Bug #68454, Bug #16373973)

• A statement with an aggregated, nongrouped outer query and an aggregated, nongrouped subquery in

the SELECT list could return incorrect results. (Bug #68372, Bug #16325175)

• Adding an ORDER BY clause following an IN subquery could cause duplicate rows to be returned. (Bug

#68330, Bug #16308085)

• If the server was started with --skip-grant-tables, ALTER USER ... PASSWORD EXPIRE

caused the server to exit. (Bug #68300, Bug #16295905)

• Configuring with -DWITH_SSL=/path/to/openssl resulted in link errors due to selection of the

incorrect libcrypto. (Bug #68277, Bug #16284051)

• If mysql is built with the bundled libedit library, the library is built as static code, to avoid linking to

a different dynamic version at runtime. Dynamic linking could result in use of a different, incompatible

version and a segmentation fault. (Bug #68231, Bug #16296509)

• Some table I/O performed by the server when calling a storage engine were missing from the statistics

collected by the Performance Schema. (Bug #68180, Bug #16222630)

• The Perl version of mysql_install_db mishandled some error messages. (Bug #68118, Bug

#16197542)

• For arguments with fractional seconds greater than six decimals, SEC_TO_TIME() truncated, rather

than rounding as it should have. (Bug #68061, Bug #16093024)

• Queries with many values in a IN() clause were slow due to inclusion of debugging code in non-

debugging builds. (Bug #68046, Bug #16078212)

145

MySQL 5.6 Release Notes

References: See also: Bug #58731, Bug #11765737.

• ALTER TABLE tbl_name ADD COLUMN col_name TIMESTAMP DEFAULT CURRENT_TIMESTAMP

ON UPDATE CURRENT_TIMESTAMP inserted 0000-00-00 00:00:00 rather than the current

timestamp if the alteration was done in place rather than by making a table copy. (Bug #68040, Bug

#16076089)

• mysqld_safe used the nonportable -e test construct. (Bug #67976, Bug #16046140)

• Nonspatial indexes only support exact-match lookups for spatial columns, but the optimizer incorrectly

used range access in some cases, leading to incorrect results. (Bug #67889, Bug #15993693)

• For EXPLAIN DELETE and EXPLAIN UPDATE the possible_keys column listed all indexes, not just

the applicable indexes. (Bug #67830, Bug #15972078)

• MySQL failed to build if configured with WITH_LIBWRAP enabled. (Bug #67018, Bug #16342793)

• CMake did not check whether the system zlib had certain functions required for MySQL, resulting in

build errors. Now it checks and falls back to the bundled zlib if the functions are missing. (Bug #65856,

Bug #14300733)

• If a dump file contained a view with one character set and collation defined on a view with a different

character set and collation, attempts to restore the dump file failed with an “illegal mix of collations” error.

(Bug #65382, Bug #14117025)

• If the server was started without a --datadir option, SHOW VARIABLES could show an empty value for

the datadir system variable. (Bug #60995, Bug #12546953)

• For debug builds, some queries with SELECT ... FROM DUAL nested subqueries raised an assertion.

(Bug #60305, Bug #11827369)

• The --log-slow-admin-statements and --log-slow-slave-statements

command options now are exposed at runtime as the log_slow_admin_statements and

log_slow_slave_statements system variables. Their values can be examined using SHOW

VARIABLES. The variables are dynamic, so their values can be set at runtime. (The options were

actually replaced by the system variables, but as system variables can be set at server startup, no option

functionality is lost.) (Bug #59860, Bug #11766693)

• UNION ALL on BLOB columns could produce incorrect results. (Bug #50136, Bug #11758009)

• An out-of-memory condition could occur while handling an out-of-memory error, leading to recursion in

error handling. (Bug #49514, Bug #11757464)

• The REPLACE() function produced incorrect results when a user variable was supplied as an argument

and the operation was performed on multiple rows. (Bug #49271, Bug #11757250)

• UNION type conversion could incorrectly turn unsigned values into signed values. (Bug #49003, Bug

#11757005)

• Setting max_connections to a value less than the current number of open connections caused the

server to exit. (Bug #44100, Bug #11752803)

• The optimizer used Loose Index Scan for some queries for which this access method is inapplicable.

(Bug #42785, Bug #11751794)

• View access in low memory conditions could raise a debugging assertion. (Bug #39307, Bug

#11749556)

146

MySQL 5.6 Release Notes

Changes in MySQL 5.6.10 (2013-02-05, General Availability)

Beginning with MySQL 5.6.10, MySQL Enterprise Edition is available for MySQL 5.6. Specifically, MySQL

Enterprise 5.6.10 includes these components previously available only in MySQL 5.5: MySQL Enterprise

Security (PAM and Windows authentication plugins), MySQL Enterprise Audit, and MySQL Thread Pool.

For information about these features, see MySQL Enterprise Edition. To learn more about commercial

products, see https://www.mysql.com/products/.

Known limitations of this release:

On Microsoft Windows, when using the MySQL Installer to install MySQL Server 5.6.10 on a host with an

existing MySQL Server of a different version (such as 5.5.30), that also has a different license (community

versus commercial), you must first update the license type of the existing MySQL Server. Otherwise,

MySQL Installer will remove MySQL Server(s) with different licenses from the one you chose with MySQL

Server 5.6.10.

On Microsoft Windows 8, updating a community release to a commercial release requires you to manually

restart the MySQL service after the update.

• Connection Management Notes

• Functionality Added or Changed

• Bugs Fixed

Connection Management Notes

• The following changes were made to the sandbox mode that the server uses to handle client

connections for accounts with expired passwords:

• There is a new disconnect_on_expired_password system variable (default: enabled). This

controls how the server treats expired-password accounts.

• Two flags were added to the C API client library: MYSQL_OPT_CAN_HANDLE_EXPIRED_PASSWORDS

for mysql_options() and CLIENT_CAN_HANDLE_EXPIRED_PASSWORDS for

mysql_real_connect(). Each flag enables a client program to indicate whether it can handle

sandbox mode for accounts with expired passwords.

MYSQL_OPT_CAN_HANDLE_EXPIRED_PASSWORDS is enabled for mysqltest unconditionally, for

mysql in interactive mode, and for mysqladmin if the first command is password.

For more information about how the client-side flags interact with

disconnect_on_expired_password, see Server Handling of Expired Passwords. (Bug #67568, Bug

#15874023, WL #6587)

Functionality Added or Changed

• InnoDB: When compressed tables were used, the calculation to compute memory usage

within the buffer pool was complex because the compressed pages could be smaller than

16KB or the user-specified page size. Although this information can be retrieved from the

INFORMATION_SCHEMA.INNODB_BUFFER_PAGE table, that operation is expensive. The following new

status variables help to simplify calculations involving buffer pool memory usage:

• Innodb_buffer_pool_bytes_data, to supplement Innodb_buffer_pool_pages_data.

• Innodb_buffer_pool_bytes_dirty, to supplement Innodb_buffer_pool_pages_dirty.

147

MySQL 5.6 Release Notes

(Bug #15842637)

• Replication: An Auto_Position column has been added to the output generated by SHOW SLAVE

STATUS. The value of this column shows whether replication autopositioning is in use. If autopositioning

is enabled—that is, if MASTER_AUTO_POSITION = 1 was set by the last successful CHANGE MASTER

TO statement that was executed on the slave—then the column's value is 1; if not, then the value is 0.

(Bug #15992220)

• In RPM packages built for Unbreakable Linux Network, libmysqld.so now has a version number.

(Bug #15972480)

• Error messages for ALTER TABLE statement using a LOCK or ALGORITHM value not supported for

the given operation were very generic. The server now produces more informative messages. (Bug

#15902911)

• If a client with an expired password connected but old_passwords was not the value required

to select the password hashing format appropriate for the client account, there was no way for the

client to determine the proper value. Now the server automatically sets the session old_passwords

value appropriately for the account authentication method. For example, if the account uses the

sha256_password authentication plugin, the server sets old_passwords=2. (Bug #15892194)

• The validate_password_policy_number system variable was renamed to

validate_password_policy. (Bug #14588121)

• In JSON-format EXPLAIN output, the attached_condition information for subqueries now includes

select# to indicate the relative order of subquery execution. (Bug #13897507)

Bugs Fixed

• Important Change; Replication: The lettercasing used for displaying UUIDs in global transaction

identifiers was inconsistent. Now, all GTID values use lowercase, including those shown in the

Retrieved_Gtid_Set and Executed_Gtid_Set columns from the output of SHOW SLAVE STATUS.

(Bug #15869441)

• Performance; InnoDB: Some data structures related to undo logging could be initialized unnecessarily

during a query, although they were only needed under specific conditions. (Bug #14676084)

• Performance; InnoDB: Optimized read operations for compressed tables by skipping redundant tests.

The check for whether any related changes needed to be merged from the insert buffer was being called

more often than necessary. (Bug #14329288, Bug #65886)

• Performance; InnoDB: Immediately after a table was created, a query against it would not use a Loose

Index Scan. The same query might use a Loose Index Scan following an ALTER TABLE on the table.

The fix improves the accuracy of the cost estimate for queries involving the grouping functions min()

and max(), and prevents the query plan from being changed by the ALTER TABLE statement. (The

more stable query plan might or might not use a Loose Index Scan.) (Bug #14200010)

• InnoDB: When the primary key of a table includes a column prefix, and a full-text index is defined on

the table, a full-text search resulted in an unnecessary warning being written to the error log. This fix

suppresses the unnecessary warning. (Bug #16169411)

• InnoDB: In online DDL operations, a DROP FOREIGN KEY clause was not allowed in an ALTER TABLE

statement that also performed any of the following:

• Adding or dropping a column.

• Adding or dropping a primary key index.

148

MySQL 5.6 Release Notes

• Making a column NULL or NOT NULL.

• Reordering columns.

• Changing the ROW_FORMAT or KEY_BLOCK_SIZE properties.

(Bug #16095573, Bug #68019)

• InnoDB: Some Valgrind warnings were issued during shutdown, while cleaning up a background thread

that handles optimization of tables containing FULLTEXT indexes. (Bug #15994393)

• InnoDB: During an online DDL operation, changing a column from nullable to NOT NULL could succeed

or fail differently depending on whether the ALTER TABLE statement used ALGORITHM=INPLACE

or ALGORITHM=COPY. An operation with ALGORITHM=COPY would succeed even if the column

contained NULL values, while an operation with ALGORITHM=INPLACE failed because of the possibility

that the column contained NULL values. Now, making a column NOT NULL in combination with the

ALGORITHM=INPLACE clause is allowed, but only if the sql_mode configuration option includes the

STRICT_TRANS_TABLES or STRICT_ALL_TABLES setting. If the ALGORITHM clause is not specified

with the ALTER TABLE statement, the online DDL operation will use ALGORITHM=INPLACE if possible,

or ALGORITHM=COPY if not. (Bug #15961327)

• InnoDB: Under certain circumstances, an InnoDB table was reported as corrupted after import

using ALTER TABLE ... IMPORT TABLESPACE. The problem was accompanied by one of these

messages:

Warning : InnoDB: The B-tree of index "PRIMARY" is corrupted.

error : Corrupt

or:

Warning : InnoDB: The B-tree of index "GEN_CLUST_INDEX" is corrupted.

error : Corrupt

This issue occurred intermittently, and primarily affected large tables. The REPAIR TABLE statement

would fix the problem reported by the error message. (Bug #15960850, Bug #67807)

• InnoDB: Names of indexes being created by an online DDL operation were being displayed incorrectly

in INFORMATION_SCHEMA tables while the operation was in progress. This fix ensures the table names

have the leading 0xff byte stripped off for INFORMATION_SCHEMA queries. This change affects the

columns:

• innodb_buffer_page.index_name

• innodb_buffer_page_lru.index_name

• innodb_cmp_per_index.index_name

• innodb_cmp_per_index_reset.index_name

• innodb_locks.lock_index

• innodb_sys_indexes.name

(Bug #15946256)

• InnoDB: ALTER TABLE statements using the online DDL feature could cause Valgrind warnings. (Bug

#15933178)

149

MySQL 5.6 Release Notes

• InnoDB: If an online DDL operation to add a unique index failed, because duplicate items were

created by concurrent DML during the online DDL operation, the ALTER TABLE operation failed

with the wrong error type. It returned ER_INDEX_CORRUPT; now it returns the new error code

ER_DUP_UNKNOWN_IN_INDEX. (It does not return ER_DUP_KEY, because the duplicate key value is not

available to be reported when this condition occurs.) (Bug #15920713)

• InnoDB: During an online DDL operation to add a unique index, DML operations that created duplicate

values could fail with an ER_DUP_KEY error even though the index had not been made visible yet.

(There was a brief time window when this condition could occur.) The fix causes the index creation

operation to fail instead, if the index would be invalid because of duplicate entries produced by

concurrent DML. (Bug #15920445)

• InnoDB: Specifying an innodb_log_file_size value of 4GB or larger was not possible on 64-bit

Windows systems. This issue only affected debug builds. (Bug #15882860)

• InnoDB: If the server crashed near the end of an online DDL ALTER TABLE statement, a subsequent

CHECK TABLE statement using the EXTENDED clause could cause a serious error. (Bug #15878013)

• InnoDB: Creating an index on a CHAR column could fail for a table with a character set with varying

length, such as utf8, if the table was created with the ROW_FORMAT=REDUNDANT clause. (Bug

#15874001)

• InnoDB: This fix ensures that in case of a serious unhandled error during an ALTER TABLE operation

that copies the original table, any data that could be needed for data recovery is preserved, in tables

using names of the form #sql-ib-table_id or #mysql50##sql-ib-table_id. (Bug #15866623)

• InnoDB: The status variable Innodb_buffer_pool_read_ahead_evicted could show an

inaccurate value, higher than expected, because some pages in the buffer pool were incorrectly

considered as being brought in by read-ahead requests. (Bug #15859402, Bug #67476)

• InnoDB: An online DDL operation to add a primary key to a table could encounter a serious error if the

table also had an index on a column prefix of a BLOB column.

This fix suspends the background purge operation while a table is being rebuilt by an ALTER TABLE

statement, if any rows containing off-page columns would be removed. Currently, to avoid excessive

space usage during the online DDL operation, avoid these types of concurrent DML operations until the

ALTER TABLE is finished:

• DELETE of rows that contain off-page columns.

• UPDATE of primary key columns in rows that contain off-page columns.

• UPDATE of off-page columns.

(Bug #14827736)

• InnoDB: The server could halt with an assertion error while creating an index:

InnoDB: Assertion failure in thread thread_num in file row0merge.cc line 465

This issue affected tables with a combination of ROW_FORMAT=REDUNDANT off-page columns, and an

index on a column prefix. (Bug #14753402)

• InnoDB: The server could halt with an assertion error when creating an index on a column prefix for a

column using a multibyte character set:

InnoDB: Assertion failure in thread thread_num in file row0merge.cc line 465

InnoDB: Failing assertion: len == ifield-<fixed_len

150

MySQL 5.6 Release Notes

(Bug #14753402)

• InnoDB: A regression introduced by the fix for Bug#14100254 would result in a “!BPAGE-

>FILE_PAGE_WAS_FREED” assertion. (Bug #14676249)

• InnoDB: INFORMATION_SCHEMA tables with InnoDB metadata, such as innodb_sys_tablestats,

displayed nonalphanumeric characters in the names of tables using an encoded format, for example with

@0024 instead of $. (Bug #14550145)

• InnoDB: If the value of innodb_force_recovery was less than 6, opening a corrupted table might

loop forever if a corrupted page was read when calculating statistics for the table. Information about

the corrupted page was written repeatedly to the error log, possibly causing a disk space issue. The fix

causes the server to halt after a fixed number of failed attempts to read the page. To troubleshoot such a

corruption issue, set innodb_force_recovery=6 and restart. (Bug #14147491, Bug #65469)

• InnoDB: With a large value for innodb_buffer_pool_size, and

innodb_buffer_pool_instances set greater than 1, pages were being incorrectly evicted from the

buffer pool. (Bug #14125092)

• InnoDB: Corruption of the innodb_ft_user_stopword_table table could cause a server exit. (Bug

#67960, Bug #16038656)

• Partitioning: Partition pruning is now enabled for tables using a storage engine that provides automatic

partitioning, such as the NDB storage engine, but which are explicitly partitioned. Previously, pruning

was disabled for all tables using such a storage engine, whether or not the tables had explicitly defined

partitions.

In addition, as part of this fix, explicit partition selection is now disabled for tables using a storage engine

(such as NDB) that provides automatic partitioning. (Bug #14827952)

References: See also: Bug #14672885.

• Replication: When using GTID-based replication, and whenever a transaction was executed on

the master but was not sent to the slave because the slave already had a transaction with that ID,

semisynchrononous replication timed out. One case in which this could happen was during a failover

operation where the new master started behind the new slave. (Bug #15985893)

• Replication: An unnecessary flush to disk performed after every transaction when using FILE as the

replication info repository type could degrade performance. Now this is done only when both data and

relay log info is stored in (transactional) tables. (Bug #15980626)

• Replication: Issuing START SLAVE UNTIL SQL_BEFORE_GTIDS = gtid_set, where gtid_set

covered a large number (tens or hundreds of millions) of transactions, could cause the server to hang.

(Bug #15968413)

• Replication: When a slave was started using --skip-innodb and replication info

file repositories (FILE being the default for both the master_info_repository and

relay_log_info_repository system variables), replication was incorrectly stopped. However,

if the slave is using file repositories and not currently migrating between info repositories, replication

should be able to work without issues. Now the server ignores errors raised when trying to open table

info repositories in such conditions.

In addition, binary log initialization was not performed correctly when starting the slave with --skip-

innodb, which caused the --log-bin option to be ignored. (Bug #15956714, Bug #67798, Bug

#15971607)

151

MySQL 5.6 Release Notes

• Replication: When temporary and persistent tables, or temporary tables using different storage engines,

are dropped in a single statement, this statement is actually written as two statements to the binary log,

each represented by its own log event. When gtid_mode is ON, each DDL event must have a GTID;

however, in such cases, the statement dropping the temporary table was uncommitted, which meant that

it was not given its own GTID.

Now, when a DDL statement dropping a temporary table and a table that is persistent, or that uses

a different storage engine, is separated in the manner just described, and the resulting logged

statement affecting only the temporary table does not implicitly commit, a commit is forced so that the

corresponding log event has own unique GTID. (Bug #15947962)

• Replication: Semisynchronous replication did not work correctly with GTIDs enabled. (Bug #15927032)

References: See also: Bug #14737388.

• Replication: When used on a binary log that had been written by a GTID-enabled server,

mysqlbinlog did not correctly handle transactions left unclosed by the omission of statements that

were ignored when the --database option was employed.

Now, whenever mysqlbinlog --database reads a GTID log event, it checks to see whether there is

an unclosed transaction, and if so, issues a commit. (Bug #15912728)

• Replication: When GTIDs were enabled, the automatic dropping of a temporary table when a client

disconnected did not always generate a GTID. Now each logged DROP TABLE statement, including any

generated by the server, is guaranteed to have its own GTID. (Bug #15907504)

• Replication: When a binary log is replayed on a server (for example, by executing a command like

mysqlbinlog binlog.000001 | mysql), it sets a pseudo-slave mode on the client connection used,

so that the server can read binary log and apply binary log events correctly. However, the pseudo-slave

mode was not disabled after the binary log dump was read, which caused unexpected filtering rules to

be applied to SQL statements subsequently executed on the same connection. (Bug #15891524)

• Replication: After dropping a column from the slave's version of a table, then altering the same column

of this table on the master (so that a type conversion would have been required had the column not been

droppped on the slave), inserts into this table caused replication to fail. (Bug #15888454)

• Replication: Use of sql_slave_skip_counter is not compatible with GTID-based replication.

Setting this variable to a nonzero value is now disallowed whenever --gtid-mode = ON, and

attempting to do so fails with an error. (Bug #15833516)

• Replication: During mysqld shutdown, global GTID variables were released before it was made certain

that all plugins had stopped using them. (Bug #14798275)

• Replication: MASTER_POS_WAIT() could hang or return -1 due to invalid updates by the slave SQL

thread when transactions were skipped by the GTID protocol. (Bug #14775893)

References: See also: Bug #15927032.

• Replication: Trying to execute a Stop event on a multithreaded slave could cause unwanted updates to

the relay log, leading the slave to lose synchronization with the master. (Bug #14737388)

• Replication: Names of databases in binary log query log events were not properly checked for length.

(Bug #14636219)

• Replication: Issuing START SLAVE concurrently with setting sql_slave_skip_counter or

slave_net_timeout could cause a deadlock. (Bug #14236151)

152

MySQL 5.6 Release Notes

• Replication: When using statement-based replication, and where the master and the slave used

table schemas having different AUTO_INCREMENT columns, inserts generating AUTO_INCREMENT

values logged for a given table on the master could be applied to the wrong table on the slave. (Bug

#12669186)

• Replication: Repeated execution of CHANGE MASTER TO statements using invalid MASTER_LOG_POS

values could lead to errors and possibly a crash on the slave. Now in such cases, the statement fails

with a clear error message. (Bug #11764602, Bug #57454)

• Microsoft Windows: Dynamic file names (with colons) are no longer allowed. Static file names using

the Alternate Data Stream (ADS) NTFS functionality of Microsoft Windows may continue to be used.

(Bug #11761752)

• Oracle RPM packages were unusable by yum due to issues with the obsoletes line in the .spec file

causing yum to interpret the package as obsoleting itself. (Bug #16298542)

• During client connection processing, the server now performs password-expiration checking after SSL

checks. (Bug #16103348)

• The plugin logging routine mishandled its argument, resulting in undefined behavior. (Bug #16002890)

• A buffer-handling problem in yaSSL was fixed. (Bug #15965288)

• Within a stored procedure, executing a multiple-table DELETE statement that used a very long table alias

could cause the server to exit. (Bug #15954896)

• Metadata locking and table definition cache routines did not always check length of names passed to

them. (Bug #15954872)

• In the absence of a FULLTEXT index on an InnoDB table, a full-text query with COUNT(*) could raise an

assertion. (Bug #15950531)

• In certain rare cases, a query using UpdateXML() could cause the server to crash. (Bug #15948580)

References: See also: Bug #13007062.

• Very long table aliases in queries could cause the server to exit. (Bug #15948123)

• An online DDL operation that dropped an index could proceed despite not having sufficient locks on the

table. This issue could cause a serious error, although the error was only observed in debug builds. (Bug

#15936065)

• A comment added to mysqldump output for the --set-gtid-purged option was malformed and

caused a syntax error when the dump file was reloaded. (Bug #15922502)

References: See also: Bug #14832472.

• Contention in the thread pool during kill processing could lead to a Valgrind panic. (Bug #15921866)

• Several OpenSSL-related memory leaks were fixed. (Bug #15921729)

• The ALTER TABLE statement can now use the LOCK=NONE clause, allowing online DDL with concurrent

DML, for child tables containing foreign key constraints. (Bug #15912214)

• Very long database names in queries could cause the server to exit. (Bug #15912213, Bug #16900358)

• AES_DECRYPT() and AES_ENCRYPT() had memory leaks when MySQL was compiled using

OpenSSL. (Bug #15909183)

153

MySQL 5.6 Release Notes

• Several OpenSSL-related Valgrind warnings were corrected. (Bug #15908967)

• An ALTER TABLE with the ADD PRIMARY KEY or ADD UNIQUE INDEX clause could encounter a

serious error if the columns for the primary key or unique index contained duplicate entries. This error

occurred intermittently, depending on how the rows were physically distributed across index blocks. (Bug

#15908291)

• Rows_log_event allocated one too few bytes for the row buffer. (Bug #15890178)

• The Performance Schema normally ignores temporary table events. User-defined temporary tables are

truncated by being re-created, but the Performance Schema did not recognize re-created temporary

tables as being temporary and raised an assertion. (Bug #15884836)

• Several code issues identified by Fortify were corrected. (Bug #15884324)

• In debug builds, the server could not start on 64-bit Windows systems when a value of 16 GB or higher

was specified for innodb_buffer_pool_size. Non-debug builds would likely have subtler issues,

such as memory being allocated for the buffer pool but not used, or read requests overlooking pages

already cached in the buffer pool.

On 32-bit Windows systems, the value of innodb_buffer_pool_instances is increased

if necessary so that no buffer pool instance is larger than 1.3 GB, due to system limitations on

memory allocation. This automatic adjustment needed for 32-bit Windows systems was incorrectly

applied to 64-bit systems also; for systems with 16 GB or larger buffer pools, the adjusted value of

innodb_buffer_pool_instances would exceed the upper limit of 64, causing an assertion error in

debug builds. (Bug #15883071)

• A heavy workload of online DDL and concurrent DML on a table on a master server could cause errors

as the changes were replicated to slave servers. For example, processing a DROP COLUMN operation

at the same time as queries referring to the dropped column could cause errors on slave servers if the

statements finished in a different order than on the master. (Bug #15878880)

• Complex IN subqueries could cause the server to exit. (Bug #15877738)

• In some cases, a cost value was printed to Optimizer Trace output without being initialized, resulting in

incorrect output. (Bug #15877453)

• Some queries, if used as prepared statements, caused the server to exit if an error occurred. (Bug

#15877062)

• If an error occurred during the final phase of an online DDL operation, some cached metadata about

the table might not be restored to its original state. This issue typically affected operations that renamed

a column, and also dropped and re-created an index on that column, in the same ALTER TABLE

statement. This issue did not affect operations that reorganize the clustered index of the table, such as

adding a new primary key. (Bug #15866734)

• The optimizer's cost-based choice between IN -> EXISTS subquery transformation and subquery

materialization was sometimes incorrect if the IN predicate was OR-ed with some other predicate. (Bug

#15866339)

References: See also: Bug #13111584.

• The session_connect_attrs Performance Schema table displayed extraneous information. (Bug

#15864703)

• For the LooseScan semijoin strategy, the optimizer could rely on an uninitialized variable. (Bug

#15849654)

154

MySQL 5.6 Release Notes

• It was possible to expire the password for an account even if the account is authenticated by an

authentication plugin that does not support password expiration. (Bug #15849009)

• If Loose Index Scan was used on a query with descending order, the result set contained NULL values

instead of the correct values. (Bug #15848665)

• For debug builds, an assertion could be raised when: 1) A view was based on a MEMORY table; 2) The

table was altered to drop some column in use by the view; 3) A SELECT was done on the view with

binary logging disabled. (Bug #15847447)

• If the server shut down unexpectedly, the presence of an InnoDB table with 1018 columns (very close to

the upper limit of 1020 columns) could cause an assertion error during server restart:

InnoDB: Failing assertion: table->n_def == table->n_cols - 3

(Bug #15834685)

• Subqueries with COUNT(DISTINCT ...)) could cause the server to exit. (Bug #15832620)

References: See also: Bug #11750963.

• Setting the validate_password_length system variable did not take into account that the minimum

value is a function of several other related system variables. Now the server will not set the value less

than the value of this expression:

validate_password_number_count

+ validate_password_special_char_count

+ (2 * validate_password_mixed_case_count)

(Bug #14850601)

• GRANT ... IDENTIFIED BY could fail to flush the privileges. (Bug #14849959)

• When the server reads the mysql.user table, it now checks for invalid native and old-native password

hashes and ignores accounts with invalid hashes. (Bug #14845445)

• The validate_password plugin did not check certain passwords. (Bug #14843970)

• mysqladmin did not properly process commands for users with expired passwords. (Bug #14833621)

• MySQL could encounter an error during shutdown on Windows XP or earlier systems. This issue did

not affect systems running Windows Vista or higher, which use atomic condition variables to represent

Windows Events. (Bug #14822849)

• An issue with locking order for the system tables and the InnoDB data dictionary could lead to an internal

deadlock within MySQL. (Bug #14805484)

• Temporary table creation during execution of INFORMATION_SCHEMA queries could result in Valgrind

warnings. (Bug #14801497)

• When used with an XPath expression that contained the output of a stored function, ExtractValue()

failed with the error Only constant XPATH queries are supported. (Bug #14798445, Bug

#67313)

• The server could halt with an assertion error due to a recently added error code:

InnoDB: unknown error code 1502

InnoDB: Assertion failure in thread thread_num in file row0mysql.cc line 683

mysqld got signal 6 ;

155

MySQL 5.6 Release Notes

Now, the server returns the error code DB_DICT_CHANGED to the client in this case. (Bug #14764015)

• The clause ALGORITHM=INPLACE clause in an ALTER TABLE statement for a partitioned table could

lead to consistency issues if a crash occurred while changes were applied to some of the underlying

tables but not all. This fix prohibits the ALGORITHM=INPLACE clause for DDL operations on partitioned

tables. (Bug #14760210)

• The sha256_password authentication plugin requires that the client connect either using SSL or have

RSA enabled. When neither condition was met, an uninformative error message was produced. Now the

error message is more informative. (Bug #14751925)

• Queries that used grouping failed when executed using a cursor if the optimizer processed the grouping

using a temporary table. (Bug #14740889)

• XA START had a race condition that could cause a server crash. (Bug #14729757)

• The server could exit when the MyISAM storage engine (rather than MEMORY) was used to materialize a

derived table. (Bug #14728469)

• The server now logs warnings at startup if the file specified for the

validate_password_dictionary_file system variable violates constraints on valid password file

contents. (Bug #14588148)

• Calculations involving self-intersecting polygons caused an assertion to be raised. (Bug #14503584)

• At startup, some options and system variables variables could be set to 1 or 0, but not ON or OFF.

MySQL programs now accept ON and OFF on the command line and in option files. (Bug #14494893)

• Output generated with mysqldump --routines could produce syntax errors when reloaded. (Bug

#14463669)

• If ALTER TABLE was killed, the server could report ER_QUERY_INTERRUPTED even if the alterations

had been made successfully. This is misleading to the user. Also, the statement would not be written to

the binary log, leading to incorrect replication (Bug #14382643)

• With the ONLY_FULL_GROUP_BY SQL mode enabled, executing a stored function twice that contains an

SQL query that is not valid with that mode enabled caused the server to exit. (Bug #13996639)

• Preloading of client plugins specified with the LIBMYSQL_PLUGINS environment variable could fail

unless the plugins were located in the hardwired default plugin directory. The C API now checks during

plugin preloading for a LIBMYSQL_PLUGIN_DIR environment variable which can be set to the path

name of the directory in which to look for client plugins.

In addition, for explicit client plugin loading, the mysql_load_plugin() and

mysql_load_plugin_v() C API functions have been modified to use the LIBMYSQL_PLUGIN_DIR

value if it exists and the --plugin-dir option was not given. If --plugin-dir is given,

mysql_load_plugin() and mysql_load_plugin_v() ignore LIBMYSQL_PLUGIN_DIR. (Bug

#13994567, Bug #18110355)

• The parser failed to return an error for some invalid UNION constructs. (Bug #13992148)

• Due to a thread race condition, the server could exit while attempting to read the Performance Schema

threads.PROCESSLIST_INFO column. (Bug #68127, Bug #16196158)

• Some messages written by the server to the error log referred to the deprecated --log-slow-

queries option rather than the --slow-query-log option. Similarly, the server referred to the

deprecated --log option rather than the --general-log-file and --log-output options. (Bug

#67892, Bug #15996571)

156

MySQL 5.6 Release Notes

• Autosizing of Performance Schema parameters could result in settings that caused excessive CPU use.

(Bug #67736, Bug #15927744)

• For single-table DELETE or UPDATE statements, EXPLAIN displayed a type value of ALL (full-table scan

access method) even if the optimizer chose to scan the table by an index access method. Now the type

value is displayed as index. (Bug #67637, Bug #15892875)

• The optimizer could choose an IN-to-EXISTS transformation for subquery execution in some cases

when subquery materialization would be cheaper. (Bug #67511, Bug #15848521)

• It is not permitted to use CREATE TABLE to create an NDB table with user-defined partitioning and a

foreign key. However, it was possible to create an NDB table with a foreign key, then add partitioning

to it using ALTER TABLE, thus creating a table which was impossible to back up or restore using

mysqldump. Now the prohibition is enforced consistently. (Bug #67492, Bug #15844519)

• The optimizer sometimes chose a nonoptimimal range scan strategy when a query included a LIMIT

clause. (Bug #67432, Bug #15829358)

• Attempting to perform an in-place upgrade from MySQL 5.1 to 5.6 causes the server to exit due to a

mismatch between the privilege structures in the two series. (This is not a supported operation, but the

server should not exit ungracefully.) (Bug #67319, Bug #14826854)

• mysqldump could fail to dump all tables in the mysql database. (Bug #67261, Bug #14771252)

• Full-text searches in InnoDB tables could return incorrect results. (Bug #67257, Bug #14771282)

• The Performance Schema normally ignores temporary table events, but sometimes failed to properly

identify a table as temporary and consequently recorded events for the table. (Bug #67098, Bug

#14756887)

• The mysql client could mishandle the delimiter command if it occurred on a line during which mysql

was looking for the end of a quoted string. (Bug #64135, Bug #13639125)

• DECIMAL multiplication operations could produce significant inaccuracy. (Bug #45860, Bug #11754279)

Changes in MySQL 5.6.9 (2012-12-11, Release Candidate)

• Deprecation and Removal Notes

• Installation Notes

• Functionality Added or Changed

• Bugs Fixed

Deprecation and Removal Notes

• Microsoft Windows: Windows Vista, Windows Server 2008, and newer support native symbolic linking

using the mklink command. This makes the MySQL Server implementation of database symbolic

links using .sym files redundant, so that mechanism is now deprecated and will be removed in a future

MySQL release. See Using Symbolic Links for Databases on Windows. (WL #6561)

Installation Notes

• The --random-passwords option for mysql_install_db is now supported for MySQL install

operations (not upgrades) using Solaris PKG packages.

157

MySQL 5.6 Release Notes

Functionality Added or Changed

• Incompatible Change; Replication: A number of variable and other names relating to GTID-based

replication have been changed, with a view to making these names more appropriate and meaningful.

The old names are no longer supported.

The features so renamed are shown in the following list:

• The disable_gtid_unsafe_statements system variable has been renamed

enforce_gtid_consistency.

• The gtid_done server system variable has been renamed gtid_executed.

The gtid_lost server system variable has been renamed gtid_purged; in addition, this variable is

no longer read-only.

• The SQL_THREAD_WAIT_AFTER_GTIDS() function has been renamed

WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS().

For more information, see Replication with Global Transaction Identifiers, and Global Transaction ID

Options and Variables. (Bug #14775984)

• For client connections restrictd by the server because the client account password is expired, the server

now permits SET PASSWORD only if the account named in the statement matches the account used by

the client. (Bug #14807074)

References: See also: Bug #14698309.

• The server now provides thread information (for SHOW PROCESSLIST) to indicate the progress of in-

place ALTER TABLE operations:

• preparing for alter table

The server is preparing to execute an in-place ALTER TABLE.

• altering table

The server is in the process of executing an in-place ALTER TABLE.

• committing alter table to storage engine

The server has finished an in-place ALTER TABLE and is committing the result.

(Bug #14790408)

• InnoDB automatically extends each secondary index by appending the primary key columns to it.

Previously, the optimizer did not take into account the primary key columns of the extended secondary

index when determining how and whether to use that index. Now the optimizer takes the primary key

columns into account, which can result in more efficient query execution plans and better performance.

The optimizer can use extended secondary keys for ref, range, and index_merge index access, for

Loose Index Scan, for join and sorting optimization, and for MIN()/MAX() optimization.

The new use_index_extensions flag of the optimizer_switch system variable permits control

over whether the optimizer takes the primary key columns into account when determining how to use an

InnoDB table's secondary indexes. By default, use_index_extensions is enabled. To check whether

disabling use of index extensions will improve performance, use this statement:

158

MySQL 5.6 Release Notes

SET optimizer_switch = 'use_index_extensions=off';

For more information, see Use of Index Extensions. (Bug #62025, Bug #12814559, Bug #56714, Bug

#11763940, WL #6266)

• mysqld now writes dates to the error log in ISO (YYYY-MM-DD hh:mm:ss) format. It also includes its

process ID following the date. Thanks to Davi Arnaut for the patch. (Bug #56240, Bug #11763523)

Bugs Fixed

• Incompatible Change: The THREAD_ID column in Performance Schema tables was widened from INT

to BIGINT to accommodate 64-bit values.

Note

As a consequence of this change, the PROCESSLIST_ID column of the threads

table is now NULL for background threads. Previously, the value was 0 for

background threads.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate this change to the performance_schema database. (Bug #14664453)

• Incompatible Change: LAST_INSERT_ID(expr) did not work for expr values greater than the largest

signed BIGINT value. Such arguments now are accepted, with some consequences for compatibility

with previous versions:

• LAST_INSERT_ID() now returns a BIGINT UNSIGNED value, not a BIGINT (signed) value.

• LAST_INSERT_ID(expr) now returns an unsigned integer value, not a signed integer value.

• For AUTO_INCREMENT columns, negative values are no longer supported.

(Bug #20964, Bug #11745891)

• Incompatible Change: Connection ID (thread ID) values greater than 32 bits can occur on some

systems (such as busy or long-running 64-bit systems), causing these problems:

• Connection IDs written to the general query log and slow query log were incorrect. This was true for

logging to both files and tables.

• The CONNECTION_ID() function could return a value with a data type too small for values larger than

32 bits.

• The mysql_thread_id() and mysql_kill() C API functions did not handle ID values

larger than 32 bits. This could result in killing the wrong thread; for example, if you invoked

mysql_kill(mysql_thread_id()).

Connection IDs now are permitted to be 64-bit values when the server supports them (when built with

64-bit data types), which has these effects:

• Connection IDs are logged correctly to the general query log and slow query log.

Note

This change involves a modification to the log tables, so after upgrading to this

release, you must run mysql_upgrade and restart the server.

159

MySQL 5.6 Release Notes

• CONNECTION_ID() returns a data type appropriate for values larger than 32 bits.

• mysql_thread_id() is unchanged; the client/server protocal has only 4 bytes for the ID value. This

function returns an incorrect (truncated) value for connection IDs larger than 32 bits and should be

avoided.

mysql_kill() still cannot handle values larger than 32 bits, but to guard against killing the wrong

thread now returns an error in these cases:

• If given an ID larger than 32 bits, mysql_kill() returns a CR_INVALID_CONN_HANDLE error.

• After the server's internal thread ID counter reaches a value larger than 32 bits, it returns an

ER_DATA_OUT_OF_RANGE error for any mysql_kill() invocation and mysql_kill() fails.

To avoid problems with mysql_thread_id() and mysql_kill(), do not use them. To get the

connection ID, execute a SELECT CONNECTION_ID() query and retrieve the result. To kill a thread,

execute a KILL statement.

(Bug #19806, Bug #11745768, Bug #65715, Bug #14236124, Bug #44728, Bug #11753308)

• Important Change; InnoDB: A DML statement using the index merge access method could lock many

rows from the table, even when those rows were not part of the final result set. This fix reduces the

excessive locking by releasing the locks of unmatched rows. This optimization affects only transactions

with isolation level equal to or less strict than READ COMMITTED; it does not apply to transactions using

REPEATABLE READ or SERIALIZABLE isolation level. (Bug #14226171)

• Important Change; Replication: Statements involving the Performance Schema tables should not

be written to the binary log, because the content of these tables is applicable only to a given MySQL

Server instance, and may differ greatly between different servers in a replication topology. The database

administrator should be able to configure (INSERT, UPDATE, or DELETE) or flush (TRUNCATE TABLE)

performance schema tables on a single server without affecting others. However, when using replication

with GTIDs enabled (see Replication with Global Transaction Identifiers), warnings about unsafe

statements updating Performance Schema tables were elevated to errors, preventing the use of

performance_schema and GTIDs together.

Similar problems were encountered with replication and system logging tables when GTIDs were

enabled.

This fix introduces the concept of a nonreplicated or local table. Now when MySQL replication

encounters a table that is marked as local, updates to this table are ignored.

This fix defines as local the following tables, which are no longer replicated:

• All tables in the performance_schema database

• mysql.general_log

• mysql.slow_log

• mysql.slave_relay_log_info

• mysql.slave_master_info

160

MySQL 5.6 Release Notes

• mysql.slave_worker_info

Before this fix, statements using the performance_schema and other tables just listed were handled

by being marked as unsafe for replication, which caused warnings during execution; the statements were

nonetheless written to the binary log, regardless of the logging format in effect.

Existing replication behavior for tables in the INFORMATION_SCHEMA database is not changed by this

fix.

For more information, see MySQL Performance Schema. See also MySQL Server Logs, and Replication

Metadata Repositories. For information about general and slow query log tables, see Selecting General

Query Log and Slow Query Log Output Destinations. (Bug #14741537)

• Important Change; Replication: Because running the server with GTIDs enabled prevented changes

to nontransactional tables, programs such as mysql_upgrade and mysql_install_db were unable

to operate on system tables that used the MyISAM storage engine and therefore could not function

correctly. Now, when running with --enforce-gtid-consistency (required whenever --gtid-

mode=ON), the server allows single statements on nontransactional tables. (Bug #14722659)

• Important Change; Replication: Formerly, the value of the Seconds_Behind_Master column

in the output of SHOW SLAVE STATUS was always set to NULL whenever the SQL thread or the

I/O thread was stopped. Now, this column is set to NULL only if the SQL thread is not running, or

if the I/O thread is not running following a check to determine whether or not the SQL thread has

processed all of the relay log. (If the SQL thread has finished processing and the I/O thread is running,

Seconds_Behind_Master is 0.) (Bug #12946333)

• Performance; InnoDB: The timing values for low-level InnoDB read operations were adjusted for

better performance with fast storage devices, such as SSD. This enhancement primarily affects read

operations for BLOB columns in compressed tables. (Bug #13702112, Bug #64258)

• InnoDB; Partitioning: Previously, when attempting to optimize one or more partitions of a partitioned

table that used a storage engine that does not support partition-level OPTIMIZE, such as InnoDB,

MySQL reported Table does not support optimize, doing recreate + analyze

instead, then re-created the entire table, but did not actually analyze it. Now in such cases, the

warning message is, Table does not support optimize on partitions. All partitions

will be rebuilt and analyzed. In addition, the entire table is analyzed after first being rebuilt.

(Bug #11751825, Bug #42822)

• InnoDB: The server could halt with an error when two kinds of operations happened simultaneously:

• A ROLLBACK of an inserted row that contained off-page columns.

• An online DDL operation involving a table of ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED

(that is, using the Barracuda file format) that rebuilt the table. For example, ADD/DROP COLUMN, ADD

PRIMARY KEY, change ROW_FORMAT.

(Bug #14842014)

• InnoDB: If the server crashed while rows were inserted into a table with a FULLTEXT index but before

the transaction was committed, an error could occur during the next startup:

InnoDB: Assertion failure in thread thread_num in file dict0dict.cc line 1019

(Bug #14826779)

• InnoDB: The server could halt with an error when accessing an InnoDB table containing a FULLTEXT

index through the HANDLER statement. (Bug #14788710)

161

MySQL 5.6 Release Notes

• InnoDB: A timeout error could occur on Windows systems when doing ALTER TABLE statements with

the DISCARD TABLESPACE or IMPORT TABLESPACE clauses, due to a temporary tablespace file

remaining in the file system. (Bug #14776799)

• InnoDB: InnoDB tables with FULLTEXT indexes could allocate memory for thread handles that was

never released, possibly leading to resource issues on Windows systems. (Bug #14759163)

• InnoDB: The server could halt with an assertion error for an ANALYZE TABLE operation, depending on

the structure of the table and its indexes:

InnoDB: Assertion failure in thread thread_num in file dict0dict.ic line 447

InnoDB: Failing assertion: pos < table->n_def

(Bug #14755452)

• InnoDB: During an online DDL operation that copies the table, the secondary index of the table could

become corrupted. (Bug #14753701)

• InnoDB: An online DDL operation for an InnoDB table incorrectly reported an empty value ('') instead

of the correct key value when it reported a duplicate key error for a unique index using an index prefix.

(Bug #14729221)

• InnoDB: If the server crashed after an online DDL CREATE INDEX operation, an error could occur while

rolling back incomplete transactions on the next startup:

InnoDB: error in sec index entry del undo in

...

InnoDB: Assertion failure in thread thread_num in file row0umod.cc line 559

(Bug #14707452)

• InnoDB: This fix improves the error handling when an ALTER TABLE operation adds a column beyond

the maximum number allowed for an InnoDB table. It also raises the maximum number of columns for

an InnoDB table from 1000 to 1020. (Bug #14705287)

• InnoDB: This fix makes MySQL more responsive to KILL QUERY statements when the query is

accessing an InnoDB table. (Bug #14704286)

• InnoDB: If the server crashed at a precise moment during an ALTER TABLE operation that rebuilt the

clustered index for an InnoDB table, the original table could be inaccessible afterward. An example of

such an operation is ALTER TABLE ... ADD PRIMARY KEY The fix preserves the original table if

the server halts during this operation. You might still need to rename the .ibd file manually to restore

the original table contents: in MySQL 5.6 and higher, rename from #sql-ib$new_table_id.ibd to

table_name.ibd within the database directory; prior to MySQL 5.6, the temporary file to rename is

table_name#1 or #2. (Bug #14669848)

• InnoDB: During an online DDL operation that rebuilt the table, a CHECK TABLE statement could report a

count mismatch for all secondary indexes. (Bug #14606472)

• InnoDB: After a FULLTEXT index was created and dropped from an InnoDB table, further ALTER

TABLE operations to add, drop, and rename columns could cause a serious error. Regression of bug

#13972248. (Bug #14504337)

• InnoDB: If an ALTER TABLE statement failed while attempting to create a FULLTEXT index for an

InnoDB table, the server could halt with an assertion error while dropping the incomplete index. (Bug

#14504174)

• InnoDB: During shutdown, with the innodb_purge_threads configuration option set greater than 1,

the server could halt prematurely with this error:

162

MySQL 5.6 Release Notes

mysqld got signal 11

A workaround was to increase innodb_log_file_size and set innodb_purge_threads=1.

The fix was backported to MySQL 5.5 and 5.1, although those versions do not have the

innodb_purge_threads configuration option so the error was unlikely to occur. (Bug #14234028)

• InnoDB: The server could halt with an error under some combinations of concurrent operations:

InnoDB: unknown error code 20

This issue originated during the 5.6 development cycle. It affected only transactions using the READ

COMMITTED andREAD UNCOMMITTED isolation levels. (Bug #13641662, Bug #12424846)

• InnoDB: This fix improves the error message when a foreign key constraint cannot be created. Instead

of referring to an inability to create a table with an auto-generated name, the message clearly states the

error:

ERROR 1215 (HY000): Cannot add foreign key constraint

Issuing a subsequent SHOW WARNINGS statement provides additional detail about any secondary

indexes that are required. (Bug #11745444, Bug #15324)

• Replication: If a table to be replicated had a FULLTEXT index, this index was not ruled out when

selecting the type of scan to be used in finding the next row, even though it cannot be used to find

the correct one. The row applier subsequently tried unsuccessfully to employ an index scan, causing

replication to fail. Now in such cases, indexes which do not provide for sequential access (such as

FULLTEXT) are not considered when determining whether to use a table, index, or hash scan for this

purpose. (Bug #14843764)

• Replication: Given a stored routine R in which the GTID_SUBTRACT() function was invoked: Once

GTID_SUBTRACT() returned NULL when called inside R, it continued to return NULL every time it was

called within R, for the remainder of the client session. (Bug #14838575)

• Replication: When using the GTID-aware master-slave protocol, the slave I/O thread used the wrong

position. When using GTIDs, the position is not normally used, but as a special case, the position was

used in addition to the GTID when the slave reconnected to the same master (even though this was not

necessary). This problem is fixed by making the GTID-aware master-slave protocol not use positions at

all any longer. (Bug #14828028)

• Replication: MySQL Enterprise Backup, mysqldump, and mysqlhotcopy could not be used with

a GTID-enabled MySQL Server, because they were unable to restore the server's GTID state and so

could not restore from any point in the binary log other than the very beginning.

As part of the fix for this problem, the gtid_purged system variable (formerly named gtid_lost) is

no longer read-only; now it is possible to add GTIDs to it when gtid_executed (formerly gtid_done)

is empty. (Bug #14787808)

• Replication: Restarting replication after the first binary log file was purged resulted in the error Got

fatal error 1236 from master when reading data from binary log: 'The slave

is connecting using CHANGE MASTER TO MASTER_AUTO_POSITION = 1, but the master

has purged binary logs containing GTIDs that the slave requires.' This led GTID-

based replication to fail. (Bug #14756691)

• Solaris: Installation using Solaris packages ran mysql_install_db during upgrade operations (this

should occur only for new installations). (Bug #14747671, Bug #16534721)

• mysql_install_db failed to honor the --user option. (Bug #15866735)

163

MySQL 5.6 Release Notes

• The optimizer could allocate insufficient memory when determining subquery execution strategies,

causing the server to exit. (Bug #14846866)

• The optimizer could raise an assertion when evaluating a range test against an IS NOT NULL condition.

(Bug #14843705)

• init_io_cache() used memset() to clear a mutex but passed the wrong mutex size. (Bug

#14838882)

• Creating an InnoDB table with a FULLTEXT index could encounter a serious error if the table name

contained nonalphanumeric characters. (Bug #14835178, Bug #16036699)

• Out-of-bounds reads could occur within filename_to_tablename(). (Bug #14834378)

• When a backup is taken using mysqldump on a server with global transaction IDs (GTIDs) enabled, the

dump file did not contain any GTID information. This eventually results in replicating the transactions

from the beginning of history when the backup is used to bring up a slave.

To enable control over GTID information written to the dump file, mysqldump now has a --set-gtid-

purged option that indicates whether to add a SET @@GLOBAL.gtid_purged statement to the output.

The following table shows the permitted option values. The default value is AUTO.

Value Meaning

OFF Add no SET statement to the output.

ON Add a SET statement to the output. An error occurs

if GTIDs are not enabled on the server.

AUTO Add a SET statement to the output if GTIDs are

enabled on the server.

(Bug #14832472)

• With LOCK TABLES in effect, CREATE TABLE IF NOT EXISTS ... LIKE could raise an assertion.

(Bug #14788976)

• An assertion could be raised executing INSERT, UPDATE, or DELETE after implicitly starting a READ

ONLY transaction in LOCK TABLES mode. (Bug #14788540)

• A query with a union and a join could crash the parser. (Bug #14786792, Bug #16076289)

• Attempting to read a utf16 file with LOAD DATA raised an assertion. (Bug #14786470)

• The automatic key generation part of derived table handling did not handle properly columns specified as

part of the VALUES() clause and caused an assertion to be raised. (Bug #14786324)

• Invalid memory reads could occur for queries that selected from a zero-length table name. (Bug

#14780820)

• SHOW PROCESSLIST output was not sorted in Id order. (Bug #14771006)

• For some SELECT statements, EXPLAIN could cause the server to exit. (Bug #14761894)

• Attempting to create an auto-increment column in an InnoDB table with a NULL type attribute could

cause a serious error. (Bug #14758479)

• A memory leak occurred for attempts to use ALTER TABLE to set a default value for a tiny, medium, or

long BLOB or TEXT column. (Bug #14756206)

164

MySQL 5.6 Release Notes

• An assertion was raised if ALTER TABLE was used to rename a column to same name as an existing

column while also reordering the renamed column using AFTER or FIRST. (Bug #14756089)

• An assertion could be raised if semijoin materialization was used to evaluate a NOT IN subquery. (Bug

#14751858)

• After issuing ALTER TABLE ... DISCARD TABLESPACE, an online DDL operation for the same table

could fail on Windows systems with an error: Got error 11 from storage engine. An ALTER

TABLE statement with the ALGORITHM=INPLACE clause could also create an empty .ibd file, making the

tablespace no longer “discarded”. (Bug #14735917)

• For some continuation handler nestings, continuation could occur at the wrong location. (Bug

#14724836)

• Starting the server with bind_address and then setting host_cache_size to 0 could result in the

server stopping for certain kinds of client connections. (Bug #14689561)

• For UPDATE statements, EXPLAIN showed the total key length in the key_len column rather than the

length of the used key parts. (Bug #14682438)

• With index condition pushdown enabled, the optimizer could produce incorrect results for derived tables.

(Bug #14640176)

• SHOW PROFILE could be used to cause excessive server memory consumption. (Bug #14629232)

• The optimizer could incorrectly use a nonspatial index to optimize spatial operations, causing an

assertion to be raised. (Bug #14600994)

• Several problems with mysql_config_editor were fixed:

• There was no error message for write errors to the configuration file.

• The --all option is not supported for the remove command, but there was no warning message for

attempts to use remove --all.

• The --all option is not supported for the set command, but there was no warning message for

attempts to use set --all.

In addition, the --user, --password, and --host options now are supported for the remove

command. When present, the remove command removes only the requested values from the login path.

If none of them is given, remove removes the entire client login path. For example, this command

removes only the user value from the client login path rather than the entire client login path:

mysql_config_editor remove --login-path=client --user

(Bug #14505672, Bug #14545989, Bug #14545999)

• A LIKE pattern with too many '%' wildcards could cause a segmentation fault. (Bug #14303860)

• Previously, the events_statements_summary_by_digest Performance Schema table was a

summary grouped by the DIGEST column alone. Now this table contains a SCHEMA_NAME column and

the digest summary is grouped by the SCHEMA_NAME and DIGEST columns.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate this change into the performance_schema database. (Bug

#14075527)

• Query rewriting to scrub passwords for logging was done even if none of the associated logs were

enabled. Also, CREATE SERVER and ALTER SERVER are now rewritten as necessary. (Bug #14073554)

165

MySQL 5.6 Release Notes

• CREATE TABLE ... SELECT could create a table with a column of type NULL, which when accessed

caused a server exit. (Bug #14021323, Bug #23280699)

• CHECK TABLE and REPAIR TABLE could crash if a MyISAM table had a corrupt key (.MYI) file. Now

the server produces an error. (Bug #13556441)

• CHECK TABLE and REPAIR TABLE could crash if a MyISAM table had a corrupt key (.MYI) file. Now

the server produces an error. (Bug #13556107, Bug #13556000)

• A “buffer too small” error message from the myisamchk command referred to the

myisam_sort_buffer_size configuration option, when it should have referred to

sort_buffer_size.

myisamchk now has a myisam_sort_buffer_size variable available as an alternative name to

sort_buffer_size. myisam_sort_buffer_size is preferable to sort_buffer_size because

its name corresponds to the myisam_sort_buffer_size server system variable that has a similar

meaning. sort_buffer_size should be considered deprecated. (Bug #11754894, Bug #46578)

• The host_cache Performance Schema table displayed some lines multiple times. This was not an

issue with the host cache itself, only with the table that provides information about the cache contents.

(Bug #67236, Bug #14764890)

• On OS X, reinitializing the query cache could cause the server to exit. Thanks to Davi Arnaut for the

patch. (Bug #67156, Bug #14741880)

• The server failed to use the query cache for queries in which a database or table name contained special

characters and the table storage engine was InnoDB. (Bug #64821, Bug #13919851)

• mysqld_safe ignored the value of the UMASK environment variable, leading to behavior different from

mysqld with respect to the access mode of created files. Now mysqld_safe (and mysqld_multi)

attempt to approximate the same behavior as mysqld. (Bug #57406, Bug #11764559)

• For dumps of the mysql database, mysqldump skipped the event table unless the --events option

was given. This no longer occurs. To skip the event table if that is desired, use the --ignore-table

option instead (Bug #55587, Bug #11762933)

• For MEMORY tables with HASH indexes, DELETE sometimes failed to delete all applicable rows. (Bug

#51763, Bug #11759445)

• On OS X, KILL could sometimes be unreliable. (Bug #37780, Bug #11748945)

Changes in MySQL 5.6.8 (2012-11-07, Release Candidate)

• Configuration Notes

• Deprecation and Removal Notes

• Installation Notes

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

Configuration Notes

• This release continues the process begun in MySQL 5.6.6 of making changes to the default values of

server parameters. The motivation for these changes is to provide better out-of-box performance and to

166

MySQL 5.6 Release Notes

reduce the need for database administrators to change settings manually. These changes are subject to

revision in future releases as we gain feedback.

In some cases, a parameter has a different fixed default value. In other cases, the server autosizes a

parameter at startup using a formula based on other related parameters or server host configuration,

rather than using a fixed value. For example, the setting for host_cache_size is its previous default

of 128, adjusted up by an amount proportional to the value of max_connections. The idea behind

autosizing is that when the server has information available to make a decision about a parameter

setting likely to be better than a fixed default, it will.

The following table summarizes changes to defaults. For variables that are autosized, the main variable

description provides additional detail about the sizing algorithm. See Server System Variables, and

InnoDB Startup Options and System Variables. Any of these default settings can be overridden by

specifying an explicit value at server startup.

Parameter Old Default New Default

host_cache_size 128 Autosized using

max_connections

innodb_log_file_size 5MB 48MB

open_files_limit 0 Autosized using

max_connections

performance_schema OFF ON

performance_schema_events_waits_history_long_size10000 Autosized

performance_schema_events_waits_history_size10 Autosize

performance_schema_max_cond_instances1000 Autosize

performance_schema_max_file_instances10000 Autosize

performance_schema_max_mutex_instances1000000 Autosize

performance_schema_max_rwlock_instances1000000 Autosize

performance_schema_max_table_handles100000 Autosize

performance_schema_max_table_instances50000 Autosize

performance_schema_max_thread_instances1000 Autosize

query_cache_size 0 1M

query_cache_type ON OFF

table_definition_cache 400 Autosized using

table_open_cache

table_open_cache 400 2000

thread_cache_size 0 Autosized using

max_connections

(WL #6216)

Deprecation and Removal Notes

• The SHOW AUTHORS and SHOW CONTRIBUTORS statements have been removed. (WL #6454)

167

MySQL 5.6 Release Notes

Installation Notes

• mysql_install_db is now a Perl script and can be used on any system with Perl installed. Previously,

it was a shell script and available only on Unix platforms.

In addition, mysql_install_db is more strict about the --datadir option value. Only the last

component of the path name is created if it does not exist; the parent directory must already exist or an

error occurs. Previously, it created any nonexistent directories in the path name.

• On Unix platforms, mysql_install_db now creates a default option file named my.cnf in the base

installation directory. This file is created from a template included in the distribution package named my-

default.cnf. You can find the template in or under the base installation directory. When started using

mysqld_safe, the server uses my.cnf file by default. If my.cnf already exists, mysql_install_db

assumes it to be in use and writes a new file named my-new.cnf instead.

With one exception, the settings in the default option file are commented and have no effect.

The exception is that the file changes the sql_mode system variable from its default of

NO_ENGINE_SUBSTITUTION to also include STRICT_TRANS_TABLES:

sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES

This setting produces a server configuration that results in errors rather than warnings for bad data in

operations that modify transactional tables. See Server SQL Modes.

The my-default.cnf template replaces the older sample option files (my-small.cnf, my-

medium.cnf, and so forth), which are no longer distributed.

• On Unix platforms, mysql_install_db supports a new option, --random-passwords, that provides

for more secure MySQL installation. Invoking mysql_install_db with --random-passwords causes

it to perform the following actions in addition to its normal operation:

• The installation process creates a random password, assigns it to the initial MySQL root accounts,

and sets the “password expired” flag for those accounts.

• The initial random root password is written to the .mysql_secret file in the directory named by the

HOME environment variable. Depending on operating system, using a command such as sudo may

cause the value of HOME to refer to the home directory of the root system user. .mysql_secret is

created with mode 600 to be accessible only to the system user for whom it is created.

If .mysql_secret already exists, the new password information is appended to it. Each password

entry includes a timestamp so that in the event of multiple install operations it is possible to determine

the password associated with each one.

• No anonymous-user MySQL accounts are created.

As a result of these actions, it is necessary after installation to start the server, connect as root using

the password written to the .mysql_secret file, and to select a new root password. Until this is done,

root cannot do anything else. This must be done for each root account you intend to use. To change

the password, you can use the SET PASSWORD statement (for example, with the mysql client). You can

also use mysqladmin or mysql_secure_installation.

New RPM install operations (not upgrades) invoke mysql_install_db with the --random-

passwords option. As a consequence, RPM installs from this version onward will have their root

168

MySQL 5.6 Release Notes

accounts secured, and will have no anonymous-user accounts. (Install operations using RPMs for

Unbreakable Linux Network are unaffected because they do not use mysql_install_db.)

For install operations using a binary .tar.gz distribution or a source distribution, you can invoke

mysql_install_db with the --random-passwords option manually to make your MySQL installation

more secure. This is recommended, particularly for sites with sensitive data.

Security Notes

• On Windows, many MySQL executables depend on the libeay32.dll and ssleay32.dll SSL

libraries at runtime. To ensure that the proper versions of these libraries are found, the install process

copies them into the same directory as the executables.

Functionality Added or Changed

• InnoDB: The InnoDB transportable tablespace feature was enhanced to allow ALTER TABLE ...

IMPORT TABLESPACE to succeed in some cases where the corresponding .cfg file was not available.

This enhancement allows recovery of data even in some cases where the system tablespace is

corrupted or deleted. (Bug #14589582, Bug #66715)

• The number of atomic operations performed by the Performance Schema was reduced. (Bug

#14658739)

• ALTER USER now can be used as a prepared statement. (Bug #66874, Bug #14646014)

• On Unix systems, the mysql client writes statements executed interactively to a history file (see mysql

Client Logging). mysql now ignores for logging purposes statements that match any pattern in the

“ignore” list. By default, the pattern list is "*IDENTIFIED*:*PASSWORD*", to ignore statements that

refer to passwords. Pattern matching is not case sensitive. Within patterns, two characters are special:

• ? matches any single character.

• * matches any sequence of zero or more characters.

To specify additional patterns, use the --histignore command option or set the MYSQL_HISTIGNORE

environment variable. (If both are specified, the option value takes precedence.) The value should be a

colon-separated list of one or more patterns, which are appended to the default pattern list.

Patterns specified on the command line might need to be quoted or escaped to prevent your command

interpreter from treating them specially. For example, to suppress logging for UPDATE and DELETE

statements in addition to statements that refer to passwords, invoke mysql like this:

shell> mysql --histignore="*UPDATE*:*DELETE*"

(Bug #48287, Bug #11756377)

Bugs Fixed

• Important Change; Replication: When running the slave with the --slave-skip-errors option,

successive skipped events (errors logged as warnings) were found to contain information from previous

warnings, which caused an excessive amount of redundant information to be written to the error log. This

problem could occur when using row-based or mixed-format binary logging.

The fix for this issue is to clear these warnings prior to processing the next skipped event. In addition,

the skipped events are now handled in the same way regardless of the value of binlog_format,

and a skipped error always causes a warning to be written to the error log, as long as the value of the

log_warnings system variable is greater than 1. (Bug #12776842)

169

MySQL 5.6 Release Notes

• Important Change: The server system variables profiling, have_profiling, and

profiling_history_size are now deprecated, and are subject to removal in a future release of the

MySQL Server. (Bug #14658683)

• InnoDB: The thread gathering persistent statistics for an InnoDB table could cause a serious error if it

accessed the table while a TRUNCATE TABLE operation was in progress:

InnoDB: Assertion failure in thread thread_num in file fsp0fsp.cc line 1882

(Bug #14765035)

• InnoDB: When a CREATE INDEX operation failed for an InnoDB FULLTEXT index due to a duplicate

key error, some allocated memory was not freed. (Bug #14759111)

• InnoDB: During a brief time window while creating an InnoDB unique index, MySQL could print a

spurious warning message:

WARNING: CANNOT FIND INDEX ?index_name IN INNODB INDEX TRANSLATION TABLE

The cause was that MySQL started enforcing the uniqueness constraint before the existence of the

index was fully registered. The fix suppresses the incorrect message during this final stage of index

creation. (Bug #14735988)

• InnoDB: An online DDL operation to create a unique index could fail to detect duplicate index values,

when the duplicate values were caused by DML operations while the index was being created. (Bug

#14733674)

• InnoDB: During an online DDL operation, a duplicate key error could be incorrectly issued if a record

was inserted and subsequently updated while the table was being rebuilt. (Bug #14723456)

• InnoDB: The auxiliary tables for FULLTEXT indexes were being created in the system tablespace,

regardless of the setting for the innodb_file_per_table configuration option. (Bug #14723291)

• InnoDB: When using the transportable tablespace feature, the ALTER TABLE ... IMPORT

TABLESPACE statement could crash if the InnoDB table being flushed contained a FULLTEXT index.

With this fix, the table data can be imported, although you must drop and re-create the FULLTEXT index

after the import operation. (Bug #14712962, Bug #67081)

• InnoDB: An assertion failure occurred when a bogus duplicate key error was flagged during online

ALTER TABLE. This issue only occurred for a table that lacked a primary key and any secondary

indexes. This patch fixes the assertion failure, but not the bogus duplicate key error, which is reported as

Bug#14723456. (Bug #14712710)

• InnoDB: The InnoDB memcached plugin can now work with tables where the underlying character set

is multibyte. (Bug #14711015, Bug #67076)

• InnoDB: If a CREATE TABLE statement failed due to a disk full error, some memory allocated during the

operation was not freed properly. (Bug #14708715)

• InnoDB: An ALTER TABLE operation on an InnoDB table containing a FULLTEXT index could cause

make the server halt with an assertion error. The fix causes all ALTER TABLE operations for such tables

to use the table-copying behavior of the ALGORITHM=COPY clause. (Bug #14681198)

• InnoDB: If the server crashed while executing TRUNCATE TABLE for an InnoDB table containing a

FULLTEXT index, further errors could occur during crash recovery, preventing the server from restarting.

(Bug #14676345)

170

MySQL 5.6 Release Notes

• InnoDB: If an InnoDB table containing a FULLTEXT index was being modified by a TRUNCATE TABLE

statement and on online DDL operation simultaneously, the server could end up with inconsistent

internal locks or could crash. (Bug #14676329)

• InnoDB: If creation of a FULLTEXT index failed because of a “row too large” condition, a subsequent

ALTER TABLE operation could cause the server to halt with an error. (Bug #14668777)

• InnoDB: If the MySQL server crashed while XA transactions were in PREPARED state, inconsistent

data could be produced during crash recovery if the query cache was enabled. The fix allows MySQL to

disable the query cache during crash recovery if required. (Bug #14658648)

• InnoDB: MySQL could crash while creating an InnoDB table if the disk became full at a specific

moment: after the .frm file was created but before the corresponding .ibd file was created. (Bug

#14645935)

• InnoDB: If the server crashed at the specific point when a change buffer entry was being merged into

a buffer pool page, the transaction log and the change buffer were left in an inconsistent state. After

a restart, MySQL could crash after reading the corresponding secondary index page. The problem

was more likely to occur in MySQL 5.5 or later, where the original insert buffering mechanism was

generalized to cover other operations. (Bug #14636528, Bug #66819, Bug #58571, Bug #61104, Bug

#65443)

• InnoDB: If a crash occurred during a CREATE TABLE operation, the InnoDB data dictionary could

be left in an inconsistent state, causing a crash if the partially created table was accessed later. (Bug

#14601290)

• InnoDB: On startup, MySQL would not start if there was a mismatch between the value of the

innodb_log_file_size configuration option and the actual size of the ib_logfile* files that make

up the redo log. This behavior required manually removing the redo log files after changing the value of

innodb_log_file_size. The fix causes MySQL to write all dirty pages to disk and re-create the redo

log files during startup if it detects a size mismatch. (Bug #14596550, WL #6494)

• InnoDB: With the innodb_file_per_table setting enabled, a DROP TABLE operation could cause

a crash, due to a race condition that depended on the timing of pending I/O requests. (Bug #14594600,

Bug #66718)

• InnoDB: If an online DDL operation failed due to a duplicate key error, caused by DML changes being

made concurrently to the table, the server could crash with an assertion error. (Bug #14591797)

• InnoDB: A query against an InnoDB table with a FULLTEXT index could crash, if the AGAINST clause

contained a character sequence that was encoded incorrectly for the character set of the table. (Bug

#14588091)

• InnoDB: If a FULLTEXT index was dropped from an InnoDB table, and the server crashed later for an

unrelated reason, an additional error could occur while attempting to access nonexistent FULLTEXT data

structures. (Bug #14586855)

• InnoDB: The server could crash with a confusing message if it ran out of space for temporary files

during index creation.

InnoDB: Assertion failure in thread thread_num in file mtr0mtr.cc line 306

InnoDB: Failing assertion: mtr->state == 12231

(Bug #14586256)

• InnoDB: An ALTER TABLE on an InnoDB table that dropped the primary key and then re-created it

with columns in a different order could cause an error. The issue affected tables where the swapped

columns referenced each other in a single-table foreign key relationship. The data dictionary could be left

171

MySQL 5.6 Release Notes

in an inconsistent state, where the table was listed in SHOW TABLES output but could not be queried or

dropped. For example, if the table was declared with primary key columns (c1,c2) and a foreign key

with c1 REFERENCES c2:

ALTER TABLE t2 DROP PRIMARY KEY, ADD PRIMARY KEY (c2, c1);

ERROR 1030 (HY000): Got error 38 from storage engine

(Bug #14548753)

• InnoDB: During an online DDL operation, a ROLLBACK affecting the same table could cause an

assertion error if the table formerly contained a FULLTEXT index. Some bookkeeping information

related to FULLTEXT indexes for InnoDB tables is preserved even after such an index is dropped. (Bug

#14503700)

• InnoDB: If a table was defined with an index key length very close to the upper length limit of 3072, a

query against that table could cause a serious error. (Bug #14500557, Bug #14537695)

• InnoDB: Table names containing non-ASCII characters were displayed incorrectly when the

MYSQL.INNODB_TABLE_STATS.TABLE_NAME column was queried. (Bug #14404879)

• InnoDB: A race condition could cause a crash during an online CREATE INDEX statement for an

InnoDB table. This bug only affected very small tables. It required a DML operation to be in progress

for the table, affecting the primary key columns, at the same time the CREATE INDEX statement was

issued. (Bug #14117641)

• InnoDB: If a transaction was started with a consistent snapshot, then new indexes were added to the

table while the transaction was in progress, a subsequent UPDATE statement could incorrectly encounter

the error:

ER_TABLE_DEF_CHANGED: insufficient history for index

This issue could cause an assertion error in debug builds. (Bug #14036214)

• InnoDB: The server could crash with an assertion error during operations on tables with

ROW_FORMAT=COMPRESSED. (Bug #14001972)

• InnoDB: In rare circumstances, during operations on an InnoDB table containing foreign keys, pages in

the buffer pool could be evicted but not written to disk, leading to data inconsistency. (Bug #13688491)

• InnoDB: In rare circumstances, MySQL could apply InnoDB undo records out of order during a

ROLLBACK of an operation that modified a BLOB column. This issue could cause an assertion error in

debug builds:

!bpage->file_page_was_freed

(Bug #13249921)

• InnoDB: In debug builds, a mismatch in the InnoDB PAGE_FREE list would cause an assertion. (Bug

#12701488)

• Partitioning: The server now skips pruning of tables (see Partition Pruning) that use a storage engine

which handles its own partitioning internally. The server now also explicitly rejects attempts to use

explicit partitioning for such tables. (Bug #14672885)

• Partitioning: When used with a table having multiple columns in its primary key, but partitioned by

KEY using a column that was not part of the primary key as the partitioning column, a query using an

aggregate function and DISTINCT such as SELECT SUM(DISTINCT pk_column_1) FROM table

WHERE pk_column_2 = constant was not handled correctly. (Bug #14495351)

172

MySQL 5.6 Release Notes

• Replication: When using a multithreaded slave, if all worker threads were kept busy, it was possible for

cleanup of an internal MTS circular buffer to fail, resulting in a full buffer and failure of the slave. (Bug

#14710881)

• Replication: Executing FLUSH LOGS in parallel with COMMIT could cause the server to hang. (Bug

#14640486)

• Replication: When invoked while gtid_mode was set to OFF, the

SQL_THREAD_WAIT_AFTER_GTIDS() function waited indefinitely, unless a timeout was specified.

In the latter case, the function could return incorrect values. Now, when gtid_mode is OFF,

SQL_THREAD_WAIT_AFTER_GTIDS() always returns NULL, as expected. (Bug #14640065)

• Replication: Partially-failed GRANT and REVOKE statements were not always handled the same way on

the master and the slave. We now log an incident event whenever an error occurs, even if it is only a

partial error, with a message stating that manual reconciliation is required. (Bug #14598585)

• Replication: There existed a gap in time between the appending of the current GTID to the server's list

of logged GTIDs and the commit of the transaction by the storage engine. On slow platforms, or when

using profiling, this could cause SELECT SQL_THREAD_WAIT_AFTER_GTIDS(gtid) to return before

the data actually reached the database.

Now the current GTID is appended to the logged GTIDs following the commit, which removes this gap

and so eliminates a possible source of inconsistency. (Bug #14116526)

• Replication: The error shown when a relay log file was missing from the relay log index file informed

the user only that the log file was not found, but did not specify the exact reason. Now in such cases,

the error message returned is Could not find target log file mentioned in relay log

info in the index file 'index_file_name' during relay log initialization. (Bug

#11758505)

• Replication: Following an insert into a nontransactional table that failed due to insufficient disk space,

the server did not properly clean up all pending events, leading to an assert or possibly to other errors.

(Bug #11750014)

• Replication: Backtick (`) characters were not always handled correctly in internally generated SQL

statements, which could sometimes lead to errors on replication slaves or cause failure of restore

operations from binary log files. (Bug #66550, Bug #14548159, Bug #29422, Bug #11746883)

• A DELETE statement for an InnoDB table could write incorrect transaction metadata into a record,

causing the server to halt with an error. To work around this issue, reduce the specified length of the

primary key to less than 1K bytes. (Bug #14731482)

• mysql_secure_installation could not change the password for an account that had

password_expired='Y' in the mysql.user table row for that account. (Bug #14726722)

• For an in-place ALTER TABLE operation on an InnoDB table that produced a duplicate-key error for

NULL values, the error message displayed the column default value rather than NULL. (Bug #14723364)

• Patches for materialized semijoins caused failures of the query plan interface used by NDBCLUSTER.

(Bug #14704659)

• mysqladmin password did not work for accounts with an expired password. (The fix for this problem

is limited to accounts with passwords that use native or “old” native hashing. It still does not handle

accounts that use SHA-256 password hashing.)

As a consequence of this patch, the restricted mode of operation enforced by the server on operations

permitted to clients with expired passwords now includes SET statements in addition to SET PASSWORD.

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MySQL 5.6 Release Notes

This is useful if the account uses a password hashing format that requires old_passwords to be set to

a value different from its default. (Bug #14698309)

• Repeated execution of a query containing a subquery that used MAX() could result in increasing

memory consumption. (Bug #14683676)

• Queries that used a nested join with a subquery in the FROM clause and an ORDER BY ... DESC

clause could return too few rows. (Bug #14678404)

• With the optimizer tracing enabled, the INFORMATION_SCHEMA.OPTIMIZER_TRACE table can be

queried to find tracing information about the last statements. However, for queries for which the results

were retrieved from the query cache, this information was not available. (Bug #14665052)

• There was a performance regression for queries using SELECT ... INTO user variables and a WHERE

condition on one or more of the variables in the INTO list. (Bug #14664077)

References: This issue is a regression of: Bug #12408412.

• In debug builds, the server could crash because db_suicide() failed to handle SIGABRT signals. (Bug

#14649493)

• USE dbname could fail with Unknown database when dbname contained multiple backtick (`)

characters. (Bug #14645196)

• Outer joins could execute inefficiently and return incorrect results if joins were pushed down to the

storage engine. (Bug #14644936)

• A prepared statement that referenced views in an IN subquery could return different results for different

executions. (Bug #14641759)

References: See also: Bug #13773979.

• Within a stored program, memory allocated to hold condition information was not released until program

exit, leading to excessive memory use. (Bug #14640599)

• Attempts to insert, update, delete from, or lock unknown Performance Schema tables failed with an

ER_TABLEACCESS_DENIED_ERROR error rather than ER_NO_SUCH_TABLE. (Bug #14633008)

• An incomplete result could be stored in the query cache when a query failed with an error (providing

that the query cache was enabled, and was set to a nonzero size). This fix ensures that it is no longer

possible for queries that finish with an error to be cached. (Bug #14621700)

References: This issue is a regression of: Bug #40264.

• The thread cache implementation worked in LIFO rather than FIFO fashion and could result in a thread

being denied service (although this was a remote possibility). (Bug #14621627)

• The server could crash when registering tables in the query cache for queries that selected from views.

(Bug #14619935)

• With semijoin and materialization optimizations enabled, a query that materialized a const table

returned incorrect results when STRAIGHT_JOIN was added. (Bug #14609394)

• Index condition pushdown in conjunction with descending index range scan could return incorrect results

if there were multiple ranges in the range scan. (Bug #14604223)

• EXPLAIN DELETE ... WHERE impossible_condition could function incorrectly when it was used

in a stored routine. (Bug #14601802)

References: This issue is a regression of: Bug #11752097.

174

MySQL 5.6 Release Notes

• Small values of max_sort_length could produce incorrect results for integer, decimal, floating-point,

or temporal data types. Now max_sort_length is ignored for those data types. (Bug #14596888)

• The configure.pl script that converts GNU configure options to CMake equivalents generated

erroneous output for the --with-client-ldflags and --with-mysqld-ldflags options. It now

ignores those options. (Bug #14593123)

• A query with a subquery and ORDER BY and LIMIT clauses returned fewer rows than expected when

executed using semijoin materialization. (Bug #14580874)

• The server printed excessive Got error 159 when reading table messages to the error log

when one transaction attempted to access a table that had been modified by another. (Bug #14579877)

• The optimizer could choose an incorrect execution plan for updates to InnoDB tables based on indexes

that use column prefixes. (Bug #14578060)

• Materialization of a subquery in the FROM clause could return the wrong number of rows if the subquery

included a LIMIT clause. (Bug #14576727)

• In-source builds modified the source file sql/share/dictionary.txt. (Bug #14562699)

• Improper memory cleanup could cause the server to exit. (Bug #14536113)

• A query with a subquery in the JOIN ... ON clause with an outer reference to a field that was out of

scope could cause the server to crash. (Bug #14498914)

• On Windows, mysql_plugin could not find my_print_defaults. (Bug #14471052)

• When used in GRANT statements, quoted user name or host name values containing leading or trailing

spaces caused privileges to be assigned incorrectly until a FLUSH PRIVILEGES statement was issued.

Now, as a result of this fix, quoted name and host identifiers used in a GRANT statement are

automatically trimmed of any leading and trailing spaces, before privileges are assigned. (Bug

#14328259)

• Granting or revoking the PROXY privilege caused the server to exit if the server was started with the

skip_name_resolve system variable enabled. (Bug #14211140)

• CREATE USER and DROP USER could fail to flush the privileges, requiring FLUSH PRIVILEGES to be

used explicitly. (Bug #13864642)

• On OS X, the version_compile_machine system variable did not include the value 64 for server

binaries compiled on a 64-bit system. (Bug #13859866)

• Access to INFORMATION_SCHEMA tables through a view could leak memory. (Bug #13734987)

• On Microsoft Windows with CMake 2.6, the build process would not stop if the create_initial_db

step failed. (Bug #13713525)

• The test in mysqld_safe for the presence of the --plugin_dir option and assignment of a default

value to it were performed before the actual argument parsing took place. (Bug #13548161)

• A cached query result was not empty at the end of statement execution as expected. This could occur

when executing queries (with the query cache enabled and set to a nonzero size) where the result was

not sent to the client such as those executed by the Event Scheduler, or when executing stored routines

containing queries while the server was running in bootstrap mode. (Bug #11755580, Bug #14609893)

• The number of connection errors from a given host as counted by the server was periodically reset, with

the result that max_connect_errors was never reached and invalid hosts were never blocked from

trying to connect. (Bug #11753779)

175

MySQL 5.6 Release Notes

References: See also: Bug #38247, Bug #43006, Bug #45584, Bug #45606.

• The Range checked for each record optimization is now used for conditions with outer query

references. (Bug #11750963)

• Random number generation during client authentication consumed excessive CPU. (Bug #66567, Bug

#14555434)

• Metadata locking resulted in excessive contention in read-only workloads involving InnoDB tables and a

low number of connections.

Now the set of metadata locks can be partitioned into separate hashes to permit connections

accessing different objects to use different locking hashes and reduce contention. The new

metadata_locks_hash_instances system variable can be used to specify the number of hashes.

(Bug #66473, Bug #14569140)

• On Windows, the Perl version of mysql_install_db created system tables in the mysql database

that were not populated properly. (Bug #65584, Bug #14181049)

• ST_Contains() and ST_Within() incorrectly reported that a polygon did not contain itself.

ST_Equals() incorrectly returned 0 for polygons that differed only in shifted vertices. (Bug #64653, Bug

#13864679)

• ST_Difference() could incorrectly produce empty polygons in the result. (Bug #64649, Bug

#13865773)

• libmysqlclient did not use symbol versioning. Thanks to Nicholas Bamber for the patch. (Bug

#64386, Bug #13788218)

• The parser rejected legal queries that involved a UNION where the right hand side query term has a table

in parenthese. (Bug #54382, Bug #11761854)

• For some queries involving ORDER BY, the optimizer chose the wrong index for accessing the table.

(Bug #45969, Bug #11754370, Bug #14338686)

• In debug builds, vio_read() printed errno rather than socket_error to the debug trace. (Bug

#28775, Bug #11746795)

Changes in MySQL 5.6.7 (2012-09-29, Release Candidate)

Beginning with MySQL 5.6.7, Oracle no longer provides binaries for OS X 10.5, Debian 5, RHEL/OL 4,

SLES 10, FreeBSD 7, Windows XP, or Windows 2003.

• Configuration Notes

• Deprecation and Removal Notes

• Functionality Added or Changed

• Bugs Fixed

Configuration Notes

• This release continues the process begun in MySQL 5.6.6 of making changes to the default values of

server parameters. The motivation for these changes is to provide better out-of-box performance and to

reduce the need for database administrators to change settings manually. These changes are subject to

revision in future releases as we gain feedback.

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MySQL 5.6 Release Notes

The following table summarizes changes to defaults. Any of these default settings can be overridden by

specifying an explicit value at server startup.

Parameter Old Default New Default

innodb_data_file_path ibdata1:10M:autoextend ibdata1:12M:autoextend

(WL #6216)

Deprecation and Removal Notes

• If the server was started with secure_auth disabled, it did not produce a warning that this is a

deprecated setting. (Bug #65462, Bug #14136937)

• The following items are deprecated and will be removed in a future MySQL release. Where alternatives

are shown, applications should be updated to use them.

• The SHOW PROFILE and SHOW PROFILES statements. Use the Performance Schema instead; see

MySQL Performance Schema.

• The unused date_format datetime_format time_format, and max_tmp_tables system

variables.

• The obsolete mysql.host table. New MySQL 5.6 installations will no longer create this table. For

upgrades, mysql_upgrade will check for this table and issue a warning about it being deprecated if it

is nonempty.

• The (undocumented) --plugin-xxx syntax for controlling plugin option xxx.

(WL #6443)

• The unused multi_range_count system variable is now deprecated, and will be removed in a future

release. (WL #6398)

• In MySQL 5.6.6, INSERT DELAYED was deprecated, to be removed in a future release. The

same is now also true for DELAYED-related system variables delayed_insert_limit,

delayed_insert_timeout, delayed_queue_size, max_delayed_threads, and

max_insert_delayed_threads, and DELAYED-related status variables Delayed_errors,

Delayed_insert_threads, Delayed_writes, and Not_flushed_delayed_rows.

Functionality Added or Changed

• Important Change; Partitioning: The maximum number of partitions for a user-partitioned table is

increased from 1024 to 8192. (Bug #11755685)

• Performance; InnoDB: A new setting O_DIRECT_NO_FSYNC was added to the

innodb_flush_method configuration option. This setting is similar to O_DIRECT, but omits the

subsequent fsync() call. Suitable for some filesystems but not others. (Bug #11754304, Bug #45892)

• InnoDB: The --innodb-read-only option lets you run a MySQL server in read-only mode. You

can access InnoDB tables on read-only media such as a DVD or CD, or set up a data warehouse with

multiple instances all sharing the same data directory. See Configuring InnoDB for Read-Only Operation

for usage details. (Bug #14143600, WL #6445)

• InnoDB: New INFORMATION_SCHEMA tables, innodb_cmp_per_index and

innodb_cmp_per_index_reset, provide statistics on InnoDB tables that use compression. The

statistics at the index level let DBAs measure whether the proportion of successful or failed compression

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MySQL 5.6 Release Notes

operations is acceptable for a particular combination of table, index, page size, and workload. Typically,

the compression failure rate should be less than 10%, particularly when using a compressed table to

handle an OLTP-style workload with frequent INSERT, UPDATE, or DELETE operations.

Because gathering those statistics could be very time consuming and would hurt

performance negatively, the new tables are enabled only when the new configuration option

innodb_cmp_per_index_enabled is set to ON. (It is OFF by default.) (WL #6347)

• InnoDB: Each data block in an InnoDB compressed table contains a certain amount of empty space

(padding) to allow DML operations to modify the row data without re-compressing the new values.

Too much padding can increase the chance of a compression failure, requiring a page split, when the

data does need to be re-compressed after extensive changes. The amount of padding can now be

adjusted dynamically, so that DBAs can reduce the rate of compression failures without re-creating

the entire table with new parameters, or re-creating the entire instance with a different page size.

The associated new configuration options are innodb_compression_failure_threshold_pct,

innodb_compression_pad_pct_max (WL #6345)

• InnoDB: You can now select the compression level for InnoDB compressed tables, from the familiar

range of 0-9 used by zlib. The compression level is controlled by the innodb_compression_level

configuration option, with a default value of 6:

• Increasing the compression level increases CPU overhead, possibly reducing the amount of storage

needed for any particular row, reducing the possibility of a compression failure and subsequent page

split.

• Decreasing the compression level reduces CPU overhead, possibly increasing the amount of storage

needed for any particular row, increasing the possibility of a compression failure and subsequent page

split.

You can also control whether compressed pages in the buffer pool are stored in the redo log when

an update operation causes pages to be compressed again. This behavior is controlled by the

innodb_log_compressed_pages configuration option. Turning off logging for compressed pages

reduces the amount of redo data that is generated, possibly improving throughput. If the compressed

page is required during crash recovery, it is compressed again at that time. (WL #6344)

• When MySQL is configured with -DWITH_SSL=system to build with OpenSSL, CMake now produces

an error if OpenSSL is older than version 1.0.1 (Bug #14167227)

• The default has changed from false to true for the --secure-auth option for mysql and the

MYSQL_SECURE_AUTH option for the mysql_options() C API function. (Bug #13789417)

• The WITH_SSL option for CMake now accepts a path_name value that indicates the path name to the

OpenSSL installation to use. This can be useful instead of a value of system when the CMake code

detects an older or incorrect installed OpenSSL version. (Another permitted way to do the same thing is

to set the CMAKE_PREFIX_PATH option to path_name.) (Bug #61619, Bug #12762891)

• The server now issues a Note diagnostic if an index is created that duplicates an existing index. (Bug

#37520, Bug #11748842)

• The MySQL client library now includes SSL support built in. When linking MySQL client programs, you

should no longer specify either -lssl or -lcrypto.

References: See also: Bug #12762891, Bug #14167227.

• The mysql_clear_password cleartext client-side authentication plugin is intended for authentication

schemes that require the server to receive the password as entered on the client side, without hashing.

Because the password is sent in the clear, this plugin should be used within the context of an encrypted

178

MySQL 5.6 Release Notes

connection, such as an SSL connection, to avoid exposing the password over the network. To make

inadvertent use of this plugin less likely, it is now required that clients explicitly enable it. This can be

done several ways:

• Set the LIBMYSQL_ENABLE_CLEARTEXT_PLUGIN environment variable to a value that begins with 1,

Y, or y. This enables the plugin for all client connections.

• The mysql, mysqladmin, and mysqlslap client programs support an --enable-cleartext-

plugin option that enables the plugin on a per-invocation basis.

• The mysql_options() C API function supports a MYSQL_ENABLE_CLEARTEXT_PLUGIN option that

enables the plugin on a per-connection basis. Also, any program that uses libmysqlclient and

reads option files can enable the plugin by including an enable-cleartext-plugin option in an

option group read by the client library.

Bugs Fixed

• Incompatible Change: Using ALTER TABLE to change the definition of a foreign key column could

cause a loss of referential integrity. For example, changing a foreign key column that contained NULL

values to be NOT NULL caused the NULL values to be the empty string. Similarly, an ALTER TABLE

IGNORE that removed rows in a parent table could break referential integrity.

The server now prohibits changes to foreign key columns with the potential to cause loss of referential

integrity. A workaround is to use ALTER TABLE ... DROP FOREIGN KEY before changing the column

definition and ALTER TABLE ... ADD FOREIGN KEY afterward. (Bug #46599, Bug #11754911)

• Important Change; Replication: When issued during an ongoing transaction, any of the following

statements that are used to control MySQL Replication now cause the transaction to be committed:

• CHANGE MASTER TO

• START SLAVE

• STOP SLAVE

• RESET SLAVE

For more information, see Statements That Cause an Implicit Commit. (Bug #13858841)

References: See also: Bug #14298750, Bug #13627921.

• Important Change: The ALTER USER statement cleared the user password in the mysql.user table.

It no longer does this. (Bug #14226518)

• Important Change: Formerly, the ExtractValue() and UpdateXML() functions supported a

maximum length of 127 characters for XPath expressions supplied to them as arguments. This limitation

has now been removed. (Bug #13007062, Bug #62429)

• Performance; InnoDB: This fix improves the performance of the InnoDB memcached plugin in several

ways:

• A background thread periodically commits changes made to the database through memcached

API calls. This commit interval based on time rather than number of operations lets you increase

the value of daemon_memcached_w_batch_size and daemon_memcached_r_batch_size

without the risk of some changes remaining uncommitted when DML activity is infrequent. You can

control the frequency of these automatic commits through the innodb_api_bk_commit_interval

configuration option.

179

MySQL 5.6 Release Notes

• When binary log support is enabled through the innodb_api_enable_binlog configuration option,

you can increase the value of daemon_memcached_w_batch_size higher than the default of 1,

allowing several DML operations to be committed together rather than a separate commit for each

one.

• Internally, the efficiency of mutexes and table opening/closing was improved for operations involving

the memcached plugin.

(Bug #14252821)

• Performance; InnoDB: The OPTIMIZE TABLE statement now updates the InnoDB persistent statistics

for that table when appropriate. (Bug #14238097)

• Performance; InnoDB: This fix removes redundant checksum validation on InnoDB pages. The

checksum was being verified both when a compressed page was read from disk and when it was

uncompressed. Now the verification is only performed when the page is read from disk. (Bug

#14212892, Bug #64170)

• Performance; Replication; Solaris: On Solaris systems, enabling slave_parallel_workers could

lead to a slowdown in event executions on the slave. (Bug #14641110)

References: See also: Bug #13897025.

• Performance; Replication: When slave_parallel_workers was enabled, an internal multiplier

representing the number of events above a certain overrun level in the worker queue was never reset

to zero, even when the excess had been taken care of; this caused the multiplier to grow without

interruption over time, leading to a slowdown in event executions on the slave. (Bug #13897025)

• Performance: View definitions (in .frm files) were not cached and thus every access to a view involved

a file read. Definitions now are cached for better performance. (Bug #13819275)

• Performance: Certain instances of subquery materialization could lead to poor performance. Subquery

materialization now is chosen only if it is less costly than the EXISTS transformation. (See Optimizing

Subqueries with Materialization, and Optimizing Subqueries with the EXISTS Strategy.)

This fix introduces a new flag for the optimizer_switch system variable named

subquery_materialization_cost_based. If the flag is on (the default), the optimizer performs a

cost-based choice between subquery materialization and IN -> EXISTS subquery transformation if

either method could be used. If the flag is off, the optimizer chooses subquery materialization over IN

-> EXISTS subquery transformation, which was the previous behavior. (Bug #13111584)

• InnoDB; Partitioning: A SELECT from a partitioned InnoDB table having no primary key sometimes

failed to return any rows where a nonempty result was expected. In such cases the server also

returned the error Can't find record in table_name or Incorrect key file for table

table_name. (Bug #13947868)

• InnoDB: When configuring the InnoDB memached plugin system table,

INNODB_MEMCACHE.CONTAINERS, a comma (“,”) and empty space are used as a delimiter for mapping

multiple columns to a memcached value. This fix allows the pipe character, (“|”), to also be used as a

delimiter. (Bug #14560228)

• InnoDB: On Windows systems, a file access error due to an incorrect value for MYSQL_DATADIR could

cause an InnoDB assertion error. The error could persist after restarting MySQL. (Bug #14558324)

• InnoDB: Inserting data of varying record lengths into an InnoDB table that used compression could

cause the server to halt with an error. (Bug #14554000, Bug #13523839, Bug #63815, Bug #12845774,

Bug #61456, Bug #12595091, Bug #61208)

180

MySQL 5.6 Release Notes

• InnoDB: The default for the innodb_checksum_algorithm, which was briefly changed to crc32

during the MySQL 5.6 development cycle, was switched back to innodb for improved compatibility of

InnoDB data files during a downgrade to an earlier MySQL version. (Bug #14525151)

• InnoDB: In an ALTER TABLE that rebuilds a table, and in particular, ADD COLUMN, DROP COLUMN,

there were some assertion failures related to FULLTEXT indexes, particularly for tables containing

more than one FULLTEXT index. The fix makes the ALTER TABLE correctly use or not use online DDL

depending on the presence of FULLTEXT indexes. If a table had a FULLTEXT index that was dropped,

any restrictions on online DDL for that table remain, due to the hidden FTS_DOC_ID column. (Bug

#14488218)

• InnoDB: Under certain conditions, the innodb_io_capacity_max configuration option now uses the

following formula to calculate a default value:

innodb_io_capacity_max = max(2000, innodb_io_capacity * 2)

The formula only takes affect when you specify a value for innodb_io_capacity at server startup and

do not specify a value for innodb_io_capacity_max. The formula is not used when setting a value

for innodb_io_capacity dynamically using a SET statement. (Bug #14469086)

• InnoDB: Under heavy load of concurrent DML and queries, an InnoDB table with a unique index could

return nonexistent duplicate rows to a query. (Bug #14399148, Bug #66134)

• InnoDB: The syntax ALTER TABLE ... DROP FOREIGN KEY ... ALGORITHM=COPY incorrectly

considered the names of foreign keys to be case-sensitive. (Bug #14394071)

• InnoDB: When an error (such as a duplicate key error) was detected during an online DDL operation,

while applying changes made to the table while an index was being built, MySQL could encounter an

assertion error if the same ALTER TABLE statement also contained any DROP INDEX clauses. (Bug

#14392805)

• InnoDB: When an InnoDB table had a system-chosen primary key, based on a unique index on non-

nullable columns, an error was issued if one of the primary key columns was altered to be nullable. The

message was:

Warning 1082 InnoDB: Table table_name has a primary key in InnoDB data

dictionary, but not in MySQL!

This issue only affected ALTER TABLE statements using the online DDL mechanism, that is, with the

ALGORITHM=INPLACE clause specified or implied. (Bug #14353985)

• InnoDB: A heavy query workload against an InnoDB table with a FULLTEXT index could cause a crash.

The issue only occurred with some number of queries per second and some number of concurrent

connections. (Bug #14347352)

• InnoDB: If an online CREATE INDEX operation failed, there was a brief period of time when concurrent

DML operations could fail because the table was considered to be in an error state. (Bug #14341099)

• InnoDB: ALTER TABLE statements for partitioned tables could cause unnecessary locking and undo

information. As part of the new online DDL feature, MySQL minimizes this overhead when practical, or

you can specify the ALGORITHM=INPLACE clause on the ALTER TABLE statement. (Bug #14322667)

• InnoDB: The mysql_install_db command could crash with an assertion error:

InnoDB: Assertion failure in thread thread_num in file trx0rseg.cc line 326

The size of the InnoDB system tablespace was being capped at 10MB, but during the 5.6 development

cycle, the minimum size of a system tablespace became slightly larger than 10MB. (Bug #14315223)

181

MySQL 5.6 Release Notes

• InnoDB: A race condition could cause assertion errors during a DROP TABLE statement for an InnoDB

table. Some internal InnoDB functions did not correctly determine if a tablespace was missing; other

functions did not handle the error code correctly if a tablespace was missing. (Bug #14251529)

• InnoDB: When more than one InnoDB temporary table was created and accessed within the same

transaction, queries on those temporary tables could fail with an ER_TABLE_DEF_CHANGED error. (Bug

#14234581)

• InnoDB: The server could crash with a combination of a transaction with SERIALIZABLE isolation level,

FLUSH TABLES ... WITH READ LOCK, and a subsequent query. The error message was:

InnoDB: Failing assertion: prebuilt->stored_select_lock_type != LOCK_NONE_UNSET

(Bug #14222066)

• InnoDB: Clustered index entries that were rolled back during the rebuild phase of an in-place ALTER

TABLE operation were not removed from the secondary index. (Bug #14221812)

• InnoDB: This fix addresses several issues regarding AUTO_INCREMENT columns when adding a column

using online DDL (that is, with ALGORITHM=INPLACE). Now the AUTO_INCREMENT_OFFSET value is

used properly, the calculation for the next value is corrected, FLOAT, DOUBLE, and unsigned INTEGER

auto-increment values are handled correctly, and overflow conditions are detected. (Bug #14219624)

• InnoDB: With the MySQL 5.6 online DDL feature, an ALTER TABLE statement to add a primary key to

an InnoDB table could succeed, even though the primary key columns contained duplicate values. (Bug

#14219515)

• InnoDB: This fix prevents online DDL operations from conflicting with foreign key operations happening

simultaneously on the same table. Updates or deletes based on CASCADE or SET NULL clauses in the

foreign key definition are blocked while the online DDL is in progress, because the information needed

in case of a ROLLBACK would not be available after the ALTER TABLE statement completes. (Bug

#14219233)

• InnoDB: A SHOW ENGINE...STATUS command could crash if an XA transaction was created using the

statement START TRANSACTION READ ONLY. (Bug #14218867)

• InnoDB: The server could crash if a read-only transaction was killed in a session that contained an

InnoDB temporary table. (Bug #14213784)

• InnoDB: An INSERT into a table after a failed online DDL operation could cause an erroneous assertion

error:

InnoDB: Failing assertion: prebuilt->trx_id == 0 || prebuilt->trx_id <= last_index->trx_id

(Bug #14176821)

• InnoDB: The server could hang at startup, during crash recovery, if the rollback of previously active

transactions conflicted with the dropping of temporary tables. With this fix, persistent statistics do not

apply to InnoDB temporary tables. (Bug #14175080)

• InnoDB: The configuration option innodb_max_io_capacity was renamed to

innodb_io_capacity_max, to emphasize its relationship to the existing innodb_io_capacity

option. (Bug #14175020)

• InnoDB: An online DDL operations to add a foreign key could incorrectly leave some memory allocated

if the DDL encountered an error. (Bug #14156259)

• InnoDB: The server could crash with a signal 8 (division by zero error) due to a race condition while

computing index statistics. (Bug #14150372)

182

MySQL 5.6 Release Notes

• InnoDB: When an auto-increment column used a FLOAT or DOUBLE data type, if the auto-increment

value became very large (larger than the maximum unsigned long long value), subsequent inserts

could fail or cause the server to halt. (Bug #14145950, Bug #55071)

• InnoDB: Deleting from an InnoDB table containing a prefix index, and subsequently dropping the index,

could cause a crash with an assertion error. (Bug #13807811)

• InnoDB: The value of the NUMBER_PAGES_CREATED and NUMBER_PAGES_WRITTEN columns of the

INFORMATION_SCHEMA.INNODB_BUFFER_POOL_STATS table were set to incorrect values, and the

NUMBER_PAGES_GET column was not being set at all. (Bug #13639187)

• InnoDB: The error message was improved for the case where an UPDATE failed because the row

included several BLOB values greater than 768 bytes each, causing the size of a row to exceed half the

page size. The old message, was misleading; it suggested using BLOBs, when the 768-byte prefix for

each BLOB column was the cause of the limit error:

Error Code 1118: Row size too large. The maximum row size for the used table

type, not counting BLOBs, is 8126. You have to change some columns to TEXT or

BLOBs

A workaround for the problem was to create the table with the ROW_FORMAT=DYNAMIC or

ROW_FORMAT=COMPRESSED clause, which is now suggested in the message. (Bug #13453036, Bug

#63507)

• InnoDB: The server could crash when updating very large BLOB values, typically 16MB or more. (Bug

#13450566)

• InnoDB: A problem in the locking mechanism could cause a serious error with queries using the

HANDLER statement. (Bug #11766271, Bug #59344)

• InnoDB: When a SELECT ... FOR UPDATE, UPDATE, or other SQL statement scanned rows in an

InnoDB table using a < or <= operator in a WHERE clause, the next row after the affected range could

also be locked. This issue could cause a lock wait timeout for a row that was not expected to be locked.

The issue occurred under various isolation levels, such as READ COMMITTED and REPEATABLE READ.

(Bug #11765218)

• InnoDB: The new online DDL feature addressed long-standing bugs where ALTER TABLE statements

caused table rebuilds unnecessarily. This particular bug applied to changing default values for

TIMESTAMP columns. (Bug #11753646, Bug #45124)

• InnoDB: Various inconsistent behaviors, including tables becoming inaccessible, were cleaned up

for ALTER TABLE statements involving InnoDB tables involved in foreign key relationships. (Bug

#11744929, Bug #5670)

• Partitioning: For tables using PARTITION BY HASH or PARTITION BY KEY, when the partition

pruning mechanism encountered a multi-range list or inequality using a column from the partitioning

key, it continued with the next partitioning column and tried to use it for pruning, even if the previous

column could not be used. This caused partitions which possibly matched one or more of the previous

partitioning columns to be pruned away, leaving partitions that matched only the last column of the

partitioning key.

This issue was triggered when both of the following conditions were met:

1. The columns making up the table's partitioning key were used in the same order as in the partitioning

key definition by a SELECT statement's WHERE clause as in the column definitions;

183

MySQL 5.6 Release Notes

2. The WHERE condition used with the last column of the partitioning key was satisfied only by a single

value, while the condition testing some previous column from the partitioning key was satisfied by a

range of values.

An example of a statement creating a partitioned table and a query against this for which the issue

described above occurred is shown here:

CREATE TABLE t1 (

c1 INT,

c2 INT,

PRIMARY KEY(c2, c1)

) PARTITION BY KEY() # Use primary key as partitioning key

PARTITIONS 2;

SELECT * FROM t1 WHERE c2 = 2 AND c1 <> 2;

This issue is resolved by ensuring that partition pruning skips any remaining partitioning key columns

once a partition key column that cannot be used in pruning is encountered. (Bug #14342883)

• Partitioning: The buffer for the row currently read from each partition used for sorted reads was

allocated on open and freed only when the partitioning handler was closed or destroyed. For SELECT

statements on tables with many partitions and large rows, this could cause the server to use excessive

amounts of memory.

This issue has been addressed by allocating buffers for reads from partitioned tables only when they are

needed and freeing them immediately once they are no longer needed. As part of this fix, memory is now

allocated for reading from rows only in partitions that have not been pruned (see Partition Pruning). (Bug

#13025132)

References: See also: Bug #11764622, Bug #14537277.

• Replication; Microsoft Windows: On 64-bit Windows platforms, values greater than 4G for the

max_binlog_cache_size and max_binlog_stmt_cache_size system variables were truncated

to 4G. This caused LOAD DATA to fail when trying to load a file larger than 4G in size, even when

max_binlog_cache_size was set to a value greater than this. (Bug #13961678)

• Replication: Updates writing user variables whose values were never set on a slave while using --

replicate-ignore-table could cause the slave to fail. (Bug #14597605)

References: This issue is a regression of: Bug #14275000.

• Replication: A manually created file named slave_worker_info in the MySQL Server's data

directory could be mistaken for the actual relay log info file. In addition, when the number of workers

(slave_parallel_workers server system variable) was decreased, the corresponding info files were

not removed as expected. (Bug #14578740)

References: See also: Bug #13804728, Bug #14550905, Bug #14550945.

• Replication: With relay_log_info_repository=FILE and slave_parallel_workers greater

than 0, changing the relay log info repository type to TABLE and restarting the slave mysqld caused a

subsequent START SLAVE statement to crash the slave. (Bug #14550945)

References: See also: Bug #13804728, Bug #14550905, Bug #14578740.

• Replication: When the number of multithreaded slave workers (as determined by setting

the slave_parallel_workers server system variable) was changed when using

relay_log_info_repository=TABLE, the mysql.slave_worker_info table did not reflect the

change. (Bug #14550905)

184

MySQL 5.6 Release Notes

References: See also: Bug #13804728, Bug #14550945, Bug #14578740.

• Replication: Using COM_BINLOG_DUMP_GTID with incorrect data could cause the server to crash. (Bug

#14509140)

• Replication: Executing the SQL_THREAD_WAIT_AFTER_GTIDS() function without binary logging

enabled could cause the server to crash. (Bug #14457883)

• Replication: An internal routine in the MySQL Replication code removed elements from a hash used

to store a mapping between databases and worker threads at the same time that the hash was being

iterated over. This could cause an unintended reordering of the has elements and thus possibly to

incorrect results from routines using this hash. (Bug #14381701)

References: See also: Bug #13864642.

• Replication: The names of the binary log and relay log Performance Schema mutexes were mistakenly

changed to names that differed from the MySQL 5.5 names. The names have been reverted to those

used in MySQL 5.5. (Bug #14366314)

• Replication: When setting up replication between a master and a slave which was using

master_info_repository=TABLE, the mysql.slave_master_info table was not updated the

first time that START SLAVE was issued. (Bug #14298750)

References: See also: Bug #13858841.

• Replication: The --disable-gtid-unsafe-statements option caused any nontransactional

DML statement involving temporary tables to be rejected with an error even with binlog_format set

explicitly to ROW, in spite of the fact that they are not written to the binary log in this case. Now, such

statements are allowed when using row-based logging, as long as any nontransactional tables affected

by the statements are also temporary tables. (Bug #14272627)

• Replication: When using multithreaded slaves, --replicate-rewrite-db rules were not honored

while assigning databases to slave worker threads, which could cause statements to be executed out of

order when this option was used. This could result in a slave that was inconsistent with the master. (Bug

#14232958)

• Replication: mysql_upgrade failed when the server was running with gtid_mode=ON and --

disable-gtid-unsafe-statements because the MySQL system tables are stored using MyISAM.

This problem is fixed by changing the default logging behavior for mysql_upgrade; logging is now

disabled by default. (Actions taken by mysql_upgrade depend on the server version, and thus should

not be replicated to slaves.) To enable logging, you can execute mysql_upgrade using the --write-

binlog option. (Bug #14221043, Bug #13833710)

• Replication: The initialization and usage of a number of internal programming objects relating to GTIDs

did not work properly with PERFORMANCE_SCHEMA. (Bug #14152637)

• Replication: The scheduler for multithreaded slaves did not take into account databases implicitly

involved in operations through foreign key dependencies, which could lead to a temporary loss of

consistency on the slave. To avoid this problem, replication events on the master that invoke foreign

key relationships between table is different databases are now marked in such a way that they can be

scheduled sequentially to avoid race conditions and thereby inconsistency. However, this can adversely

affect performance. (Bug #14092635)

• Replication: When using a multithreaded slave, the repository type employed for the relay log info log

was not always used automatically for worker repositories as expected. (Bug #13804728)

References: See also: Bug #14550905, Bug #14550945, Bug #14578740.

185

MySQL 5.6 Release Notes

• Replication: It was possible for the multithreaded slave coordinator to leak memory when the slave was

stopped while waiting for the next successful job to be added to the worker queue. (Bug #13635612)

• Replication: The Master_id column of the mysql.slave_master_info and

mysql.slave_relay_log_info tables showed the slave's server ID instead of the master's server

ID. (Bug #12344346)

• Replication: Statements such as UPDATE ... WHERE primary_key_column = constant LIMIT

1 are flagged as unsafe for statement-based logging, despite the fact that such statements are actually

safe. In cases where a great many such statements were run, this could lead to disk space becoming

exhausted do to the number of such false warnings being logged. To prevent this from happening, a

warning suppression mechanism is introduced. This warning suppression acts as follows: Whenever the

50 most recent ER_BINLOG_UNSAFE_STATEMENT warnings have been generated more than 50 times

in any 50-second period, warning suppression is enabled. When activated, this causes such warnings

not to be written to the error log; instead, for each 50 warnings of this type, a note is written to the error

log stating The last warning was repeated N times in last S seconds. This continues

as long as the 50 most recent such warnings were issued in 50 seconds or less; once the number of

warnings has decreased below this threshold, the warnings are once again logged normally.

The fix for this issue does not affect how these warnings are reported to MySQL clients; a warning

is still sent to the client for each statement that generates the warning. This fix also does not make

any changes in how the safety of any statement for statement-based logging is determined. (Bug

#11759333, Bug #51638)

References: See also: Bug #11751521, Bug #42415.

• ALTER TABLE ... DROP FOREIGN KEY that did not name the foreign key to be dropped caused a

server crash. Now the foreign key name is required. (Bug #14530380)

• In-place ALTER TABLE operations for InnoDB tables could raise an assertion attempting to acquire a

lock. (Bug #14516798)

• mysql_secure_installation did not work if old_passwords was set to 2 (use the

sha256_password authentication plugin). (Bug #14506073)

• Index condition pushdown in conjunction with descending index range scan caused a performance

regression. (Bug #14503142)

• Item_cache_str::save_in_field() dereferenced a null pointer if the cached value was NULL.

(Bug #14501403)

• A query with GROUP BY ... WITH ROLLUP comparing a grouping column using the IN operator

caused an assertion to be raised. (Bug #14500792)

• In debug builds, with semijoin enabled, GROUP BY ... WITH ROLLUP that did not use a temporary

table could cause a server crash. (Bug #14499409)

• An assertion was raised when using the join cache for a query that contained an IN subquery query with

a subquery that is expected to return a single row but returned more than one. (Bug #14499331)

• The optimizer could raise an assertion when grouping and sorting in descending order on an indexed

column. (Bug #14498999)

• Polygons with holes could cause a server crash for spatial operations. (Bug #14497827)

• For complex conditions, the optimizer could produce an incorrect range construction and return incorrect

query results. (Bug #14497598)

186

MySQL 5.6 Release Notes

• In mysql_com.h, the CLIENT_CONNECT_ATTRS and CLIENT_PLUGIN_AUTH_LENENC_CLIENT_DATA

symbols incorrectly were defined as the same value. (Bug #14482472)

• The Threads_running status variable was not updated properly. (Bug #14471011)

• GROUP_CONCAT() with DISTINCT or ORDER BY on GEOMETRY values caused a server crash. (Bug

#14468106)

• With a password policy of STRONG and a password of 100 characters or more,

VALIDATE_PASSWORD_STRENGTH() could cause a server crash. (Bug #14458293)

• PASSWORD(NULL) and OLD_PASSWORD(NULL) could cause a server crash. (Bug #14458217)

• The explicit_defaults_for_timestamp system variable was not visible (for example, with SHOW

VARIABLES), so it was not possible to make runtime decisions based on its value. (Bug #14409088)

• When resolving outer fields, Item_field::fix_outer_fields() creates new Item_refs for each

execution of a prepared statement, so these must be allocated in the runtime memroot. The memroot

switching before resolving JOIN::having caused these to be allocated in the statement root, leaking

memory for each prepared statement execution. (Bug #14409015)

• An ALTER TABLE for an InnoDB table that attempted to add an index and also change the nullability of

a column participating in that index raised an assertion. (Bug #14404635)

• For debug builds, if one session used a DDL statement to alter an InnoDB table, another session could

raise an assertion failure if it had a pre-alter consistent snapshot of the table. (Bug #14365043)

• The result set could contain extra rows for queries on MyISAM tables that used the

SQL_BUFFER_RESULT modifier and a subquery. (Bug #14348858)

• The --server-public-key option for mysql and mysqltest has been renamed to --server-

public-key-path to reflect that it refers to a file and for consistency with related server-side variable

naming. Also, this option now is available only if MySQL was built with OpenSSL (not yaSSL) because

yaSSL does not support the necessary RSA encryption. (Bug #14348721)

• The RPM spec file now also runs the test suite on the new binaries, before packaging them. (Bug

#14318456)

• Inside a stored program, references to stored program variables in XML functions such as

ExtractValue() failed after the first execution of the stored program. (Bug #14317442)

• The Performance Schema used listed the nanosecond timer by default for stages and statements in the

setup_timers table. But if this timer was not available on a given platform (such as Windows), timing

for stages and statements failed to work. Now the idle, stage, and statement timers used the preferred

timers if they are available, but alternate timers if not. (Bug #14298586)

• Some queries for which the optimizer used index condition pushdown in conjunction with ref access

could be very slow if the index was read in descending order. (Bug #14287654, Bug #14503142)

• Queries executed using MaterializeScan semijoin strategy and a materialized subquery could return too

many rows. (Bug #14272788)

• A LooseScan semijoin could return duplicate rows from the outer table. (Bug #14271594)

• The Performance Schema generated different digests for a statement before and after selecting a

database. (Bug #14256311)

• The Performance Schema digest-generation code could fail with a race condition. (Bug #14250296)

• The server did not build with gcc 4.7. (Bug #14238406)

187

MySQL 5.6 Release Notes

• An optimizer trace could crash attempting to print freed subquery items. (Bug #14238404)

• With semijoin optimization enabled, subqueries in the WITH CHECK OPTION clause of view definitions

were evaluated incorrectly. (Bug #14230177)

• ALTER SERVER, CREATE SERVER, and DROP SERVER with an empty server name caused a server

crash. (Bug #14220942)

• ALTER TABLE with DISCARD TABLESPACE or IMPORT TABLESPACE did not acquire a sufficiently

strong metadata lock to prevent a concurrent ALTER TABLE statement with ADD or DROP from modifying

the tablespace. This could result in warnings or raise an assertion. (Bug #14213236)

• WEIGHT_STRING() could crash if given a bad flags argument. (Bug #14211236)

• REQUIRE ISSUER clauses for GRANT statements were not rewritten properly for logging and caused a

server crash. (Bug #14211069)

• If a call to socket() failed, the Performance Schema created instrumentation for it anyway. (Bug

#14209598)

• Some queries with a HAVING clause with a function that referred to a function in the WHERE list with a

subquery as parameter caused an assertion to be raised. (Bug #14209318)

• String allocation could cause Valgrind warnings. (Bug #14201818)

• For queries that used range access, the optimizer could read uninitialized data, resulting in Valgrind

warnings. (Bug #14200538)

• mysql_upgrade did not set the STATS_PERSISTENT=0 table option for InnoDB tables in the mysql

database. (Bug #14195056)

• In debug builds, the optimizer raised an unnecessary (too strict) assertion about MyISAM key lengths.

(Bug #14179461)

• Join processing could attempt to clean up a temporary table that had not been instantiated, causing a

server crash. (Bug #14168270)

• Incorrect internal conversion of string-format dates could cause a server crash. (Bug #14167911)

• For JSON-format EXPLAIN statements, derived tables were not handled properly and caused a server

crash. (Bug #14167499)

• In debug builds, comparisons for strings that had the ucs2_unicode_520_ci collation could raise an

assertion. (Bug #14161973)

• In-place ALTER TABLE did not work for a table with a GEOMETRY column, even if the alteration did not

involve that column. (Bug #14140927)

• For nonexistent files, the Performance Schema file I/O instrumentation sometimes did extra work or was

subject to instrumentation leaks. (Bug #14113704)

• Small sort_buffer_size values could result in a server crash. (Bug #14111180)

• Within a trigger, references to a temporary table used during the query execution process could end up

pointing to nonexisting fields on subsequent executions, causing a server crash. (Bug #14105951)

• Negative values could be erroneously reported for some columns in the

buffer_pool_pages_in_flush row in the information_schema.innodb_metrics table. (Bug

#14090287)

188

MySQL 5.6 Release Notes

• JSON-format EXPLAIN statements could raise an assertion or cause the server to hang for statements

with an impossible-WHERE clause and subqueries in ORDER BY or GROUP BY clauses. (Bug #14084642)

• The FirstMatch strategy for semijoins produced incorrect results for some queries with multiple inner

tables. (Bug #14081638)

• With materialization and semijoins enabled, some queries with an OR condition could produce incorrect

results. (Bug #14075016)

• In-place ALTER TABLE did not handle autopartitioning storage engines such as NDB. (Bug #14063233)

• RELEASE SAVEPOINT did not have sufficient checks for the XA transaction state to prevent a savepoint

from being released while the transaction was in a prepared state. (Bug #14062726)

• Improper error handling for CREATE SERVER, DROP SERVER, and ALTER SERVER could raise an

assertion. (Bug #14061851)

• Improper initialization by spatial functions could cause a server crash the first time they were invoked

following server startup. (Bug #14015762)

• For JSON-format EXPLAIN statements, improper handling of subqueries could cause an assertion to be

raised. (Bug #13956275)

• SELECT on a partitioned table that used a join buffer could cause a server crash. (Bug #13949549)

• Polygon sorting by spatial functions could be done incorrectly and cause a server crash. (Bug

#13938850)

• For DELETE statements, WHERE clause row retrieval that should access only the index tree could raise

an assertion. (Bug #13919180)

• The argument for LIMIT must be an integer, but if the argument was given by a placeholder in a

prepared statement, the server did not reject noninteger values such as '5'. (Bug #13868860)

• Some arguments could cause ST_Buffer() to crash. (Bug #13832749, Bug #13833019)

• Queries that used the ST_Contains and Within() functions yielded incorrect results when argument

columns had a spatial index. (Bug #13813064)

• CHECK TABLE and REPAIR TABLE could crash if a key definition differed in the .frm and .MYI files of

a MyISAM table. Now the server produces an error. (Bug #13555854)

• The optimizer used a full index scan for cases for which a Loose Index Scan was preferable. (Bug

#13464493)

References: This issue is a regression of: Bug #12540545.

• COUNT(DISTINCT(SELECT 1)) could be evaluated incorrectly if the optimizer used Loose Index Scan.

(Bug #13444084)

References: See also: Bug #13813126.

• A query for a FEDERATED table could return incorrect results when the underlying table had a compound

index on two columns and the query included an AND condition on the columns. (Bug #12876932)

• In debug builds, an InnoDB assertion was overly aggressive about prohibiting an open range. (Bug

#66513, Bug #14547952)

• Starting the server with bind_address=* is supposed to cause the server to accept TCP/IP

connections on all server host IPv6 and IPv4 interfaces if the server host supports IPv6, or TCP/IP

189

MySQL 5.6 Release Notes

connections on all IPv4 addresses otherwise. But the server sometimes did not correctly detect when

IPv6 was not supported, and failed to start. (Bug #66303, Bug #14483430)

• Queries with ALL over a UNION could return an incorrect result if the UNION result contained NULL. (Bug

#65902, Bug #14329235)

• In-place ALTER TABLE incorrectly handled indexes using key prefixes by using a copy algorithm. (Bug

#65865, Bug #14304973)

• The ST_Contains() and Within() functions yielded an incorrect result when used on a column with

a SPATIAL index. (Bug #65348, Bug #14096685)

• For some queries, the optimizer used index_merge access method when this was more work than ref

access. (Bug #65274, Bug #14120360)

• The GeomFromWKB() function did not return NULL if the SRID argument was NULL, and non-NULL SRID

values were not included in the converted result. (Bug #65094, Bug #13998446)

• Internal temporary MyISAM tables were unnecessarily registered in an open-table list protected by a

global mutex, causing excessive mutex contention. (Bug #65077, Bug #14000697)

• In prepared statements, MYSQL_TYPE_DATE parameters when converted to an integer were handled

as MYSQL_TYPE_DATETIME values and the conversion produced incorrect results. (Bug #64667, Bug

#13904869)

• “Illegal mix of collation” errors were returned for some operations between strings that should have been

legal. (Bug #64555, Bug #13812875)

• COUNT(DISTINCT(IF ...)) could be evaluated incorrectly if the optimizer used Loose Index Scan.

(Bug #64445, Bug #13813126)

References: See also: Bug #13444084.

• The argument to the --ssl-key option was not verified to exist and be a valid key. The resulting

connection used SSL, but the key was not used. (Bug #62743, Bug #13115401)

• With statement-based binary logging, stored routines that accessed but did not modify tables took too

strong a lock for the tables, unnecessarily blocking other statements that also accessed those tables.

(Bug #62540, Bug #13036505)

• mysqlhotcopy failed for databases containing views. (Bug #62472, Bug #13006947, Bug #12992993)

• Adding a LIMIT clause to a query containing GROUP BY and ORDER BY could cause the optimizer to

choose an incorrect index for processing the query, and return more rows than required. (Bug #54599,

Bug #11762052)

• mysqlbinlog did not accept input on the standard input when the standard input was a pipe. (Bug

#49336, Bug #11757312)

• There was a performance regression for queries that used GROUP BY and COUNT(DISTINCT). (Bug

#49111, Bug #11757108)

• mysqldump could dump views and the tables on which they depend in such an order that errors

occurred when the dump file was reloaded. (Bug #44939, Bug #11753490)

190

MySQL 5.6 Release Notes

Changes in MySQL 5.6.6 (2012-08-07, Milestone 9)

Note

This is a milestone release, for use at your own risk. Upgrades between milestone

releases (or from a milestone release to a GA release) are not supported.

Significant development changes take place in milestone releases and you may

encounter compatibility issues, such as data format changes that require attention

in addition to the usual procedure of running mysql_upgrade. For example, you

may find it necessary to dump your data with mysqldump before the upgrade and

reload it afterward. (Making a backup before the upgrade is a prudent precaution in

any case.)

• Binary Logging

• Configuration Notes

• Deprecation and Removal Notes

• Performance Schema Notes

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

Binary Logging

• Performance: The server now implements group commit for the binary log: Multiple commits are

grouped in memory, then written and flushed to disk as a group rather than individually. This reduces

the number of writes and flushes, improving performance of binary logging. Group commit works for all

storage engines. InnoDB implements some optimizations to take advantage of group commit capability.

These system variables were added in conjunction with group commit:

• binlog_order_commits: Whether to commit transactions in the same order they are written to the

binary log or permit them to be committed in parallel.

• binlog_max_flush_queue_time: How long in microseconds to keep reading transactions from the

flush queue before proceeding with the group commit.

• innodb_flush_log_at_timeout: Write and flush logs every N seconds.

(WL #5223)

Configuration Notes

• This MySQL release implements changes to the default values of several server parameters. The

motivation for these changes is to provide better out-of-box performance and to reduce the need for

database administrators to change settings manually. These changes are subject to revision in future

releases as we gain feedback. (See Changes to Server Defaults.)

In some cases, a parameter has a different fixed default value. In other cases, the server autosizes a

parameter at startup using a formula based on other related parameters or server host configuration,

rather than using a fixed value. For example, the setting for back_log is its previous default of 50,

adjusted up by an amount proportional to the value of max_connections. The idea behind autosizing

191

MySQL 5.6 Release Notes

is that when the server has information available to make a decision about a parameter setting likely to

be better than a fixed default, it will.

The following table summarizes changes to defaults. For variables that are autosized, the main variable

description provides additional detail about the sizing algorithm. See Server System Variables, and

InnoDB Startup Options and System Variables. Any of these default settings can be overridden by

specifying an explicit value at server startup.

Parameter Old Default New Default

back_log 50 Autosized using

max_connections

binlog_checksum NONE CRC32

--binlog-row-event-max-

size

1024 8192

flush_time 1800 (on Windows) 0

innodb_autoextend_increment8 64

innodb_buffer_pool_instances1 8 (platform dependent)

innodb_checksum_algorithm INNODB CRC32

innodb_concurrency_tickets500 5000

innodb_file_per_table 0 1

innodb_old_blocks_time 0 1000

innodb_open_files 300 Autosized using

innodb_file_per_table,

table_open_cache

innodb_stats_on_metadata ON OFF

join_buffer_size 128KB 256KB

max_allowed_packet 1MB 4MB

max_connect_errors 10 100

performance_schema OFF ON

performance_schema_events_waits_history_long_size10000 Autosized

performance_schema_events_waits_history_size10 Autosized

performance_schema_max_cond_instances1000 Autosized

performance_schema_max_file_instances10000 Autosized

performance_schema_max_mutex_instances1000000 Autosized

performance_schema_max_rwlock_instances1000000 Autosized

performance_schema_max_table_handles100000 Autosized

performance_schema_max_table_instances50000 Autosized

performance_schema_max_thread_instances1000 Autosized

sql_mode '' (empty string) NO_ENGINE_SUBSTITUTION

sync_master_info 0 10000

sync_relay_log 0 10000

192

MySQL 5.6 Release Notes

Parameter Old Default New Default

sync_relay_log_info 0 10000

With regard to compatibility with previous releases, the most important changes are:

• innodb_file_per_table is enabled (previously disabled)

• innodb_checksum_algorithm is CRC32 (previously INNODB)

• binlog_checksum is CRC32 (previously NONE)

Therefore, if you are upgrading an existing MySQL installation, have not already changed the values of

these parameters from their previous defaults, and backward compatibility is a concern, you may want

to explicitly set these parameters to their previous defaults. For example, put these lines in the server

option file:

[mysqld]

innodb_file_per_table=0

innodb_checksum_algorithm=INNODB

binlog_checksum=NONE

Those settings preserve compatibility as follows:

• With the new default of innodb_file_per_table enabled, ALTER TABLE operations following an

upgrade will move InnoDB tables that are in the system tablespace to individual .ibd files. Using

innodb_file_per_table=0 will prevent this from happening.

• Setting innodb_checksum_algorithm=INNODB permits binary downgrades after upgrading to this

release. With a setting of CRC32, InnoDB would use checksumming that older MySQL versions cannot

use.

• With binlog_checksum=NONE, the server can be used as a replication master without causing

failure of older slaves that do not understand binary log checksums.

(WL #6216)

Deprecation and Removal Notes

• Important Change: INSERT DELAYED is now deprecated, and will be removed in a future release. Use

INSERT (without DELAYED) instead. (Bug #13985071)

• The YEAR(2) data type is now deprecated because it is problematic. YEAR(2) columns in existing

tables are treated as before, but YEAR(2) in new or altered tables are converted to YEAR(4). Support

for YEAR(2) will be removed entirely in a future MySQL release. For more information, see 2-Digit

YEAR(2) Limitations and Migrating to 4-Digit YEAR. (WL #6219)

Performance Schema Notes

• The Performance Schema is now enabled by default (the performance_schema system variable is

enabled by default). To disable it, set performance_schema=off at server startup.

In addition, the Performance Schema now automatically sizes the values of several of its parameters at

server startup if they are not set explicitly. For example, it sizes the parameters that control the sizes of

the events waits tables this way. To see which parameters are sized under this policy, use mysqld --

verbose --help and look for those with a default value of −1, or see Performance Schema System

Variables.

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MySQL 5.6 Release Notes

For each autosized parameter that is not set at server startup (or is set to −1), the Performance Schema

determines how to set its value based on the value of the following system values, which are considered

as “hints” about how you have configured your MySQL server:

max_connections

open_files_limit

table_definition_cache

table_open_cache

To override autosizing for a given parameter, set it a value other than −1 at startup. In this case, the

Performance Schema assigns it the specified value.

At runtime, SHOW VARIABLES displays the actual values that autosized parameters were set to.

If the Performance Schema is disabled, its autosized parameters remain set to −1 and SHOW

VARIABLES displays −1. (WL #6135)

Security Notes

• These security improvements were implemented:

• MySQL now provides a method for storing authentication credentials encrypted in an option file named

.mylogin.cnf. To create the file, use the mysql_config_editor utility. The file can be read later

by MySQL client programs to obtain authentication credentials for connecting to a MySQL server.

mysql_config_editor writes the .mylogin.cnf file using encryption so the credentials are not

stored as clear text, and its contents when decrypted by client programs are used only in memory.

In this way, passwords can be stored in a file in non-cleartext format and used later without ever

needing to be exposed on the command line or in an environment variable. For more information, see

mysql_config_editor — MySQL Configuration Utility.

The .mylogin.cnf file can contain multiple sets of options, known as “login paths.” This makes it

easy to set up multiple “personalities” for connecting to different MySQL servers. Any of these can

be selected by name later using the --login-path option when you invoke a client program. See

Command-Line Options that Affect Option-File Handling.

• MySQL now supports stronger encryption for user account passwords, available through an

authentication plugin named sha256_password that implements SHA-256 password hashing. This

plugin is built in, so it is always available and need not be loaded explicitly. For more information,

including instructions for creating accounts that use SHA-256 passwords, see SHA-256 Pluggable

Authentication.

Other changes associated with the introduction of the sha256_password plugin:

• The old_passwords system variable previously permitted values of 1 or 0 to control whether “old”

or “new” MySQL native password hashing was used by the CREATE USER and GRANT statements

and the PASSWORD() function. Now old_passwords permits a value of 2 to select use of SHA-256

password hashing.

Note

Previously, old_passwords permitted values of OFF or ON as synonyms for

0 or 1. That is no longer true.

• SHA-256 password hashing (old_passwords=2) uses a random salt value, which makes the

result from PASSWORD() nondeterministic. Consequently, statements that use this function are no

longer safe for statement-based replication and cannot be stored in the query cache.

194

MySQL 5.6 Release Notes

• If MySQL is built with OpenSSL, RSA encryption can be used to transmit passwords

during the client connection process. The sha256_password_private_key_path and

sha256_password_public_key_path system variables permit the private and public key files to

be named on the server side. The Rsa_public_key status variable displays the public key value.

The mysql and mysqltest clients support a --server-public-key option permitting the public

key file to be specified explicitly when connecting to the server. (This option is implemented through

a new MYSQL_SERVER_PUBLIC_KEY option to the mysql_options() C API function.)

MySQL Connector support: Connectors that use the C client library should work with

sha256_password with no changes. Connectors that implement the authentication process for

themselves must be updated to account for changes in the client/server protocol.

• The server now has a --default-authentication-plugin option to specify the default

plugin to associate with new accounts for which no plugin is named explicitly. Permitted values

are mysql_native_password (use MySQL native passwords; this is the default value) and

sha256_password (use SHA-256 passwords). This option also changes the initial old_passwords

value to be consistent with the password hashing method required by the default plugin, if necessary.

Note

If you use this option to change the default authentication method to a value

other than mysql_native_password, clients older than MySQL 5.5.7 will no

longer be able to connect because they will not understand the change to the

authentication protocol.

• The mysql.user table now has a password_expired column to enable DBAs to expire account

passwords and require users to reset their password. The default password_expired value is 'N',

but can be set to 'Y' with the new ALTER USER statement. After an account's password has been

expired, all operations performed by the account in subsequent connections to the server result in

an error until the user issues a SET PASSWORD statement to establish a new account password. For

more information, see ALTER USER Statement, and Server Handling of Expired Passwords.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate this change into the mysql database.

Caution

Update: ALTER USER also set the Password column to the empty string,

so do not use this statement in 5.6.6. This problem has been fixed in MySQL

5.6.7.

• MySQL now has provision for checking password security:

• In statements that assign a password supplied as a cleartext value, the value is checked

against the current password policy and rejected if it is weak (the statement returns an

ER_NOT_VALID_PASSWORD error). This affects the CREATE USER, GRANT, and SET PASSWORD

statements. Passwords given as arguments to the PASSWORD() and OLD_PASSWORD() functions

are checked as well.

195

MySQL 5.6 Release Notes

• The strength of potential passwords can be assessed using the new

VALIDATE_PASSWORD_STRENGTH() SQL function, which takes a password argument and returns

an integer from 0 (weak) to 100 (strong).

Both capabilities are implemented by the validate_password plugin. If the plugin is not installed,

the affected statements and PASSWORD() and OLD_PASSWORD() work as before (no password

checking), and VALIDATE_PASSWORD_STRENGTH() always returns 0.

The validate_password plugin also implements a set of system variables corresponding to the

parameters that control password checking. If the plugin is installed, you can modify these variables to

configure the password policy.

The validate_password plugin is written using the MySQL plugin API, which has been extended to

support writing password-validation plugins.

For more information, see The Password Validation Plugin. For information about writing password-

checking plugins, see Writing Password-Validation Plugins.

• mysql_upgrade now produces a warning if it finds user accounts with passwords hashed with

the older pre-4.1 hashing method. Such accounts should be updated to use more secure password

hashing. See Password Hashing in MySQL

(Bug #65461, Bug #14136939, WL #2739, WL #2392, WL #5602, WL #5603)

• For the WITH_SSL CMake option, no is no longer a permitted value or the default value. The default is

now bundled. Consequently, MySQL now is always built with SSL support.

Functionality Added or Changed

• Incompatible Change: It is now explicitly disallowed to assign the value DEFAULT to stored procedure

or function parameters or stored program local variables (for example with a SET var_name =

DEFAULT statement). This was not previously supported, or documented as permitted, but is flagged as

an incompatible change in case existing code inadvertently used this construct. It remains permissible to

assign DEFAULT to system variables, as before, but assigning DEFAULT to parameters or local variables

now results in a syntax error.

After an upgrade to MySQL 5.6.6 or later, existing stored programs that use this construct produce a

syntax error when invoked. If a mysqldump file from 5.6.5 or earlier is loaded into 5.6.6 or later, the load

operation fails and affected stored program definitions must be changed. (WL #6230)

• Incompatible Change: The --safe-mode server option has been removed. (WL #5185, WL #6311)

• Important Change; Partitioning: MySQL nows supports partition lock pruning, which allows for many

DDL and DML statements against partitioned tables using MyISAM (or another storage engine that

employs table-level locking) to lock only those partitions directly affected by the statement. These

statements include (but are not limited to) many SELECT, SELECT ... PARTITION, UPDATE,

REPLACE, INSERT, and other statements. This enhancement improves especially the performance of

many such statements when used with tables having many (32 or more) partitions. For a complete list of

affected statements with particulars, and other information, see Partitioning and Locking. (Bug #37252,

Bug #11748732)

• Important Change; Replication: It is now possible, in the event that a multithreaded slave fails while

running with the --relay-log-recovery option, to switch it safely to single-threaded mode despite

the presence of any gaps with unprocessed transactions in the relay log. To accomplish this, you can

now use START SLAVE [SQL_THREAD] UNTIL SQL_AFTER_MTS_GAPS to cause the slave SQL

196

MySQL 5.6 Release Notes

threads to run until no more such gaps are found in the relay log. Once this statement has completed,

you can change the slave_parallel_workers system variable, and (if necessary) issue a CHANGE

MASTER TO statement before restarting the slave. (Bug #13893363)

References: See also: Bug #13893310.

• Important Change; Replication: INSERT ON DUPLICATE KEY UPDATE is now marked as unsafe

for statement-based replication if the target table has more than one primary or unique key. For more

information, see Determination of Safe and Unsafe Statements in Binary Logging. (Bug #58637, Bug

#11765650, Bug #13038678)

• Important Change; Replication: The SHOW BINARY LOGS statement (and its equivalent SHOW

MASTER LOGS) may now be executed by a user with the REPLICATION CLIENT privilege. (Formerly,

the SUPER privilege was necessary to use either form of this statement.) (WL #6236)

• Important Change: In MySQL, the TIMESTAMP data type differs in nonstandard ways from other data

types:

• TIMESTAMP columns not explicitly declared with the NULL attribute are assigned the NOT NULL

attribute. (Columns of other data types permit NULL values if not explicitly declared with the NOT NULL

attribute.) Setting such a column to NULL sets it to the current timestamp.

• The first TIMESTAMP column in a table, if not declared with the NULL attribute or an explicit DEFAULT

or ON UPDATE attribute, is automatically assigned the DEFAULT CURRENT_TIMESTAMP and ON

UPDATE CURRENT_TIMESTAMP attributes.

• TIMESTAMP columns following the first one, if not declared with the NULL attribute or an explicit

DEFAULT attribute, are automatically assigned DEFAULT '0000-00-00 00:00:00' (the “zero”

timestamp). For inserted rows that specify no explicit value for such a column, the column is assigned

'0000-00-00 00:00:00' and no warning occurs.

Those nonstandard behaviors remain the default for TIMESTAMP but now are deprecated and this

warning appears at startup:

[Warning] TIMESTAMP with implicit DEFAULT value is deprecated.

Please use --explicit_defaults_for_timestamp server option (see

documentation for more details).

As indicated by the warning, to turn off the nonstandard behaviors, enable the new

explicit_defaults_for_timestamp system variable at server startup. With this variable enabled,

the server handles TIMESTAMP as follows instead:

• TIMESTAMP columns permit NULL values if not explicitly declared with the NOT NULL attribute. Setting

such a column to NULL sets it to NULL, not the current timestamp.

• No TIMESTAMP column is assigned the DEFAULT CURRENT_TIMESTAMP or ON UPDATE

CURRENT_TIMESTAMP attributes automatically. Those attributes must be explicitly specified.

• TIMESTAMP columns declared as NOT NULL and without an explicit DEFAULT attribute are treated as

having no default value. For inserted rows that specify no explicit value for such a column, the result

depends on the SQL mode. If strict SQL mode is enabled, an error occurs. If strict SQL mode is not

enabled, the column is assigned the implicit default of '0000-00-00 00:00:00' and a warning

occurs. This is similar to how MySQL treats other temporal types such as DATETIME.

To upgrade servers used for replication, upgrade the slaves first, then the master. Replication

between the master and its slaves should work provided that all use the same value of

explicit_defaults_for_timestamp:

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MySQL 5.6 Release Notes

1. Bring down the slaves, upgrade them, configure them with the desired value of

explicit_defaults_for_timestamp, and bring them back up.

The slaves will recognize from the format of the binary logs received from the master that the master

is older (predates the introduction of explicit_defaults_for_timestamp) and that operations

on TIMESTAMP columns coming from the master use the old TIMESTAMP behavior.

2. Bring down the master, upgrade it, and configure it with the same

explicit_defaults_for_timestamp value used on the slaves, and bring it back up.

(Bug #63034, Bug #13344629, Bug #55131, Bug #11762529, WL #6292)

• Performance; InnoDB: Many DDL operations on InnoDB tables can now be performed online, without

making the tables unavailable for queries. Some operations, such as creating or dropping indexes, even

allow DML statements (INSERT, UPDATE, DELETE) on the table while the operation is in progress. A

single online DDL operation can also take the place of a sequence of statements, such as several DROP

INDEX statements, ALTER TABLE ... ADD COLUMN, and then several CREATE INDEX statements.

See InnoDB and Online DDL for full details.

An additional effect of this change occurs for consistent-read transactions that try to re-read data from a

table which was changed by ALTER TABLE in another session. Instead of receiving an empty set, the

transaction will receive an error (ER_TABLE_DEF_CHANGED, “Table definition has changed, please retry

transaction”). (Bug #58368, Bug #11765404, Bug #11872643, Bug #12325508, Bug #11765266, Bug

#60689, WL #5526, WL #5545, WL #6251, WL #6255)

• Performance; InnoDB: The persistent statistics feature for InnoDB tables is now enabled

by default, and can be controlled at the level of individual tables. This feature involves the

configuration options innodb_stats_persistent, innodb_stats_auto_recalc, and

innodb_stats_persistent_sample_pages, and the clauses STATS_PERSISTENT,

STATS_AUTO_RECALC, and STATS_SAMPLE_PAGES of the CREATE TABLE and ALTER TABLE

statements. See Configuring Persistent Optimizer Statistics Parameters for usage details. (WL #6175,

WL #6189)

• Performance; InnoDB: The MySQL server now includes the widely used memcached in-memory

caching system, and a plugin that allows fast NoSQL-style access to InnoDB tables through the

memcached protocol. This access method avoids the overhead of SQL parsing and constructing a

query optimization plan. You can store the underlying data in a single InnoDB table, or spread it across

multiple tables. You can read and write data through both memcached and SQL. For example, you can

do fast single-key lookups through memcached get calls, and do statistical reports across all the data

through SQL.

Several configuration options let you fine-tune this system, in particular to balance raw

performance against durability and consistency of data. The main new configuration

options are daemon_memcached_option, daemon_memcached_r_batch_size,

daemon_memcached_w_batch_size, innodb_api_trx_level, innodb_api_enable_mdl, and

innodb_api_enable_binlog.

See InnoDB memcached Plugin for full details. (WL #5824, WL #6218)

• InnoDB: For systems with constant heavy workloads, or workloads that fluctuate widely,

several new configuration options let you fine-tune the flushing behavior for InnoDB

tables: innodb_adaptive_flushing_lwm, innodb_max_dirty_pages_pct_lwm,

innodb_max_io_capacity (changed in subsequent point releases to innodb_io_capacity_max),

and innodb_flushing_avg_loops. These options feed into an improved formula used by the

innodb_adaptive_flushing option. See Configuring Buffer Pool Flushing. (WL #5666)

198

MySQL 5.6 Release Notes

• InnoDB: InnoDB tables now support the notion of “transportable tablespaces”, allowing .ibd files to be

exported from a running MySQL instance and imported into another running instance. The FOR EXPORT

clause of the FLUSH TABLES statement writes any unsaved changes from InnoDB memory buffers to

the .ibd file. After copying the .ibd file and a separate metadata file to the other server, you can use

the DISCARD TABLESPACE and IMPORT TABLESPACE clauses of the ALTER TABLE statement to

bring the table data into a different MySQL instance.

For more information, see Importing InnoDB Tables. (WL #5522, WL #6168, WL #6169)

• InnoDB: InnoDB now supports the DATA DIRECTORY='directory' clause of the CREATE TABLE

statement, which permits creating tables outside the data directory. For more information, see Creating

Tables Externally. (WL #5980)

• Replication: The STOP SLAVE option SQL_BEFORE_GTIDS did not function correctly, and the

SQL_AFTER_GTIDS option for the same statement did not function at all. (Bug #13810456)

• Replication: Added the slave_rows_search_algorithms system variable for mysqld,

which determines the search algorithms used for finding matches for slave updates when

slave_allow_batching is enabled, including whether or not table or index hashing is used with

searches employing a primary or unique key, some other key, or no key.

• The Performance Schema has a new system variable,

performance_schema_session_connect_attrs_size, and new status variable,

Performance_schema_session_connect_attrs_lost. The system variable is the amount of

preallocated memory per thread reserved to hold connection attribute key/value pairs. If the aggregate

size of connection attribute data sent by a client is larger than this amount, the Performance Schema

truncates the attribute data and increments the status variable. See Performance Schema Connection

Attribute Tables. (Bug #14076427)

• yaSSL was upgraded from version 1.7.2 to 2.1.4. (Bug #13713205)

References: See also: Bug #13706828.

• The optimizer's cost model for disk-sweep Multi-Read Range (DS-MRR) has been improved. The

improved cost model makes it more likely that DSMRR will be used for queries that read much data from

disk. (WL #6082)

• Previously, the default value for the bind_address system variable was 0.0.0.0, which causes the

server to accept TCP/IP connections on all server host IPv4 interfaces. To make it easier to use IPv6

connections without special configuration, the default bind_address value now is *. This is similar to

0.0.0.0, but causes the server to also accept TCP/IP connections on all IPv6 interfaces if the server

host supports IPv6. (Another way to accept IPv4 and IPv6 connections is by using bind_address=::,

but in this case an error occurs if the server host does not support IPv6.) (WL #6301)

• It is now possible for client programs to pass connection attributes to the server in the form of

key/value pairs. Attributes are manipulated using the MYSQL_OPT_CONNECT_ATTR_RESET

and MYSQL_OPT_CONNECT_ATTR_DELETE options for the mysql_options() C API

function, and the MYSQL_OPT_CONNECT_ATTR_ADD option for the new mysql_options4()

function. Connection attributes are exposed through the session_connect_attrs and

session_account_connect_attrs Performance Schema tables.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the performance_schema database.

For more information, see C API Function Reference, and MySQL Performance Schema. (WL #5924)

199

MySQL 5.6 Release Notes

• Previously, for semijoin processing the outer query specification was limited to simple table scans or

inner joins using comma syntax, and view references were not possible. Now outer join and inner join

syntax is permitted in the outer query specification, and the restriction that table references must be base

tables has been lifted. (WL #5561)

• To improve scalability by reducing contention among sessions for the global lock on the open tables

cache, the cache now can be partitioned into several smaller cache instances. A session now need

lock only one instance to access it for DML statements. This segments cache access among instances,

permitting higher performance for operations that need to use the cache when many there are many

sessions accessing tables. (DDL statements still require a lock on the entire cache, but such statements

are much less frequent than DML statements.)

A new system variable, table_open_cache_instances, permits control over the number of cache

instances. Each instance has a size of table_open_cache / table_open_cache_instances. By

default, the number of instances is 1.

Three new status variables provide information about the operation of the open tables cache.

Table_open_cache_hits and Table_open_cache_misses indicate the number of hits and

misses or lookups in the cache. Table_open_cache_overflows indicates how many times, after a

table is opened or closed, an instance has an unused entry and the size of the instance is larger than

table_open_cache / table_open_cache_instances. (WL #5772)

• The generic “procedure API” has been removed from the server. This was formerly present as a means

of writing server procedures, but went unused except for PROCEDURE ANALYSE(). Removing the

interface simplifies aspects of the internal procedure representation that were related to code no longer

in the server but had a negative effect on its operation, in the sense that these aspects hindered the

ability of the optimizer to perform better on more common query types. In addition, this code hindered

future optimizer development and its removal will have benefit that development.

PROCEDURE ANALYSE() remains available, but is no longer implemented using a public interface.

(For information, see Using PROCEDURE ANALYSE.) One consequence of removing the procedure

interface is that EXPLAIN SELECT ... PROCEDURE ANALYSE() now works where previously it

produced an error. (WL #6242)

Bugs Fixed

• Incompatible Change: Metadata was handled incorrectly for objects such as tables or views that were

used in a stored program. Metadata for each such object was gathered at the beginning of program

execution, but not updated if DDL statements modified the object during program execution (or modified

it between executions of the program if the program remained in the stored program cache). This

resulted in mismatches between the actual object structure and the structure the stored program

believed the object to have during execution, and caused problems such as data errors or server

crashes.

Now metadata changes to objects used in a stored program are detected during execution and affected

statements within the program are reparsed so that they use the updated metadata.

Example: Suppose that a stored program executes this statement in a loop and that the columns in the

table t1 are altered during loop execution:

SELECT * FROM t1;

Previously, errors occurred because program execution did not detect that SELECT * evaluates to a

different set of columns after the change. Now the table change is detected and the SELECT is reparsed

to determine the new set of columns.

200

MySQL 5.6 Release Notes

Reparsing occurs for other cases as well, such as t1 being changed from a base table to a view or a

TEMPORARY table. For more information, see Caching of Prepared Statements and Stored Programs.

There is a possible incompatibility regarding the new behavior: Application code that assumed the

previous behavior and implemented a workaround may need to be changed.

Other instances of corrected problems:

• SELECT * within a stored program could fail for TEMPORARY tables created within the program using

prepared statements.

• “Unknown column” errors or bad data could result from changing the set of columns in a table used

within a stored program between executions of the program or while the table was used within a

program loop. Errors could also occur under similar circumstances for a view if the view definition was

changed, for a TEMPORARY table if the table was dropped.

• Failure of triggers to notice metadata changes in objects accessed within the program could cause

trigger malfunction.

• Failure of a stored program to notice metadata changes in objects accessed within the program could

cause replication to fail.

(Bug #61434, Bug #12652835, Bug #55678, Bug #11763018, Bug #64574, Bug #13840615, Bug

#33843, Bug #11747732, Bug #33289, Bug #11747626, Bug #33255, Bug #11747619, Bug #33000, Bug

#11747566, Bug #27011, Bug #11746530, Bug #33083, Bug #11747581, Bug #32868, Bug #11747537,

Bug #12257, Bug #11745236, WL #4179)

• Important Change; NDB Cluster: mysqld_safe now traps Signal 13 (SIGPIPE) so that this signal no

longer kills the MySQL server process. (Bug #33984)

• Performance; InnoDB; Partitioning: The statistics used by the optimizer for queries against partitioned

InnoDB tables were based only on the first partition of each such table, leading to use of the wrong

execution plan. (Bug #13694811)

References: This issue is a regression of: Bug #11756867.

• Performance; InnoDB: Improved the efficiency of InnoDB code with regard to CPU cache coherency.

(Bug #14034087)

• Performance; InnoDB: Improved the efficiency of the system calls to get the system time to record the

start time for a transaction. This fix reduces potential cache coherency issues that affected performance.

(Bug #13993661)

• Performance; InnoDB: Improved the algorithm related to adaptive flushing. This fix increases the rate

of flushing in cases where compression is used and the data set is larger than the buffer pool, leading to

eviction. (Bug #13990648, Bug #65061)

• Performance; InnoDB: Improved the efficiency of the COMMIT operation for InnoDB tables, by reducing

the potential for context switching and acquiring/re-acquiring mutexes while the operation is in progress.

(Bug #13989037)

• Performance; InnoDB: The order in which flushes are performed when the

innodb_flush_neighbors configuration option is enabled was improved. The algorithm makes the

neighbor-flushing technique faster on HDD storage, while reducing the performance overhead on SSD

storage. (innodb_flush_neighbors typically is not needed for SSD hardware.) (Bug #13798956)

201

MySQL 5.6 Release Notes

• Performance; InnoDB: This fix improves the speed of DROP TABLE for InnoDB tables by removing

a scan of the buffer pool to remove entries for the adaptive hash index. This improvement is most

noticeable on systems with very large buffer pools and the innodb_adaptive_hash_index option

enabled. (Bug #13704145, Bug #64284)

• Performance; Replication: All changes made as part of a given transaction are cached; when the

transaction is committed, the contents of this cache are written to the binary log. When using global

transaction identifiers, the GTID identifying this transaction must be the first event among all events in

the cache belonging to the transaction.

Previously, a portion of the cache was preallocated as a buffer when the transaction began; upon

commit it was completed with a valid GTID. However, because it was not possible to perform a seek in

the cache, it was necessary to flush it to a temporary file, and then seek within this file. When the cache

buffer is not big enough to accommodate all changes comprising a given transaction, it swapped the

data to disk, then reinitialized the cache to have the buffer properly filled with the correct data again.

The buffer was actually flushed and the cache reinitialized every time a GTID event was written, even

in those cases in which all events making up a given transaction fit within the cache buffer, which could

negatively impact the performance of binary logging (and thus replication) when using GTIDs.

Now the cache is reinitialized only when it is actually necessary—in other words, only when the cache is

in fact swapped to disk.

In addition, the fix for this issue addresses a missing unlock operation when the server failed to write

an empty transaction group and reduces the amount of code needed for prepending the GTID to the

contents of the cache before flushing the cache to disk. (Bug #13877432)

References: See also: Bug #13738296.

• Performance: Within stored programs, the overhead of making statements log friendly was incurred

even when the corresponding log was not enabled. (Bug #12884336)

• Performance: The MD5() and SHA1() functions had excessive overhead for short strings. (Bug

#49491, Bug #11757443, Bug #60227, Bug #14134662)

• InnoDB; Replication: When binary log statements were replayed on the slave, the Com_insert,

Com_update, and Com_delete counters were incremented by BEGIN statements initiating transactions

affecting InnoDB tables but not by COMMIT statements ending such transactions. This affected these

statements whether they were replicated or they were run using mysqlbinlog. (Bug #12662190)

• InnoDB: Dropping an InnoDB temporary table could leave behind the .ibd file if the table was created

with the innodb_file_per_table setting enabled. On Windows systems, this could cause an

additional problem: repeated attempts to drop the file for 2000 seconds. In addition to resolving the

incorrect path name used to drop the file, this fix also limits the retry loop to 10 seconds, for example if

the file cannot be removed because it is locked by a backup process. (Bug #14169459)

• InnoDB: When importing an InnoDB tablespace representing a compressed table, unnecessary

checksum calculations were being performed. (Bug #14161424)

• InnoDB: If MySQL crashed during an ALTER TABLE t DISCARD TABLESPACE operation, it could

leave InnoDB in a state where it crashes at the next startup. The error message was:

InnoDB: Error: a record lock wait happens in a dictionary operation!

(Bug #14146981)

• InnoDB: A race condition could cause a crash during an online CREATE INDEX statement for an

InnoDB table. This bug only affected very small tables. It required a DML operation to be in progress

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MySQL 5.6 Release Notes

for the table, affecting the primary key columns, at the same time the CREATE INDEX statement was

issued. (Bug #14117641)

• InnoDB: An assertion error could occur if an XA transaction was created within a session designated as

read-only. (Bug #14108709)

• InnoDB: If a row was deleted from an InnoDB table, then another row was re-inserted with the same

primary key value, an attempt by a concurrent transaction to lock the row could succeed when it should

have waited. This issue occurred if the locking select used a WHERE clause that performed an index scan

using a secondary index. (Bug #14100254, Bug #65389)

• InnoDB: This fix improves the accuracy of the data in the INFORMATION_SCHEMA table

innodb_metrics for systems with innodb_buffer_pool_instances set to greater than 1. The

improved information applies to the number of pages flushed from the buffer pool, specifically these

entries in the table:

buffer_flush_batch_total_pages

buffer_flush_neighbor_total_pages

buffer_flush_adaptive_total_pages

buffer_flush_sync_total_pages

buffer_flush_background_total_pages

buffer_LRU_batch_total_pages

(Bug #14037167)

• InnoDB: In a transaction using the REPEATABLE READ isolation level, an UPDATE or DELETE statement

for an InnoDB table could sometimes overlook rows recently committed by other transactions. As

explained in Consistent Nonlocking Reads, DML statements within a REPEATABLE READ transaction

apply to rows committed by other transactions, even if a query could not see those rows. (Bug

#14007649, Bug #65111)

• InnoDB: During an ANALYZE TABLE statement for an InnoDB table, the server could hang (in non-

debug builds), or an assertion error could occur, indicating recursive acquisition of a lock (in debug

builds). (Bug #14007109)

• InnoDB: An assertion could be raised if an InnoDB table was moved to a different database using

ALTER TABLE ... RENAME while the database was being dropped by DROP DATABASE. (Bug

#13982017)

• InnoDB: Querying the INFORMATION_SCHEMA.INNODB_TRX or related tables while the server was

running a heavy InnoDB workload could cause a crash, with messages in the error log referring to the

function fetch_data_into_cache_low. This issue arose during new feature work and only affected

MySQL 5.6. (Bug #13966453)

• InnoDB: Fixes a recently introduced issue with InnoDB persistent statistics, that could cause a crash

(non-debug builds) or assertion error (debug builds). (Bug #13946118)

• InnoDB: Including a % character in a query using an InnoDB FULLTEXT index could cause a crash.

(FULLTEXT indexes for InnoDB tables are a new feature, still under development.) (Bug #13940669,

Bug #64901)

• InnoDB: Using the KILL statement to terminate a query could cause an unnecessary message in the

error log:

[ERROR] Got error -1 when reading table table_name

(Bug #13933132)

203

MySQL 5.6 Release Notes

• InnoDB: When a table was renamed, the InnoDB persistent statistics were not associated with the new

table name. (Bug #13920437)

• InnoDB: If the server crashed while dropping an InnoDB temporary table or an index on a temporary

table, further errors could occur during crash recovery, preventing the server from restarting. (Bug

#13913670)

• InnoDB: A FULLTEXT query for an InnoDB table could filter the search terms incorrectly if a term using

the minus operator was followed by another term using the plus operator. (Bug #13907075)

• InnoDB: The performance_schema counters for InnoDB RW-locks did not record some cases where

mini-transactions acquired locks. (Bug #13860722)

• InnoDB: Deleting a huge amount of data from InnoDB tables within a short time could cause the

purge operation that removes delete-marked records to stall. This issue could result in unnecessary

disk space use, but does not cause any problems with data integrity. If this issue causes a disk space

shortage, restart the server to work around it. This issue is only likely to occur on 32-bit platforms. (Bug

#13847885)

• InnoDB: A slave server in a replication configuration could exit while creating an InnoDB temporary

table. (Bug #13838761)

• InnoDB: The server could crash when using the SAVEPOINT statement in conjunction with InnoDB

tables containing FULLTEXT indexes. (Bug #13831840)

• InnoDB: With the innodb_force_recovery configuration option set to 2 or greater, a shutdown could

hang after the message:

InnoDB: Waiting for purge thread to be suspended

This issue was introduced during recent changes within the MySQL 5.6 development cycle. (Bug

#13830371)

• InnoDB: Running concurrent bulk inserts on a server with auto_increment_offset=1,

auto_increment_increment greater than 1, and innodb_autoinc_lock_mode=1 could result in

intermittent errors like the following, even with the primary key set to auto_increment and omitted from

the INSERT statement:

Duplicate entry 'value' for key 'PRIMARY'

The workaround was to set auto_increment_offset=1 or innodb_autoinc_lock_mode=0

(“traditional”). (Bug #13817703, Bug #61209)

• InnoDB: The server could halt with an assertion error when DDL and DML operations were run on the

same InnoDB table simultaneously:

InnoDB: Error: a record lock wait happens in a dictionary operation!

This fix stems from the online DDL feature in MySQL 5.6. (Bug #13641926)

• InnoDB: During an ALTER TABLE statement to create a primary key for an InnoDB table, some column

characteristics could be set incorrectly, leading to errors during subsequent queries. The incorrect data

could be the maximum length for a column prefix, or the state of the NOT NULL flag.

In MySQL 5.1, this fix applies to the InnoDB Plugin, but not the built-in InnoDB storage engine. (Bug

#13641275)

204

MySQL 5.6 Release Notes

• InnoDB: An ALTER TABLE statement for an InnoDB table that dropped one index and create

another could fail with an error code 1280, and displaying the wrong index name in the message. (Bug

#13029445, Bug #62544)

• InnoDB: If the innodb_undo_tablespaces and innodb_undo_logs configuration options were

specified to refer to separate undo tablespaces, and the associated tablespaces did not exist, that error

condition was not being correctly detected during startup. (Bug #13016100)

• InnoDB: The error handling and message was improved for attempting to create a foreign key with a

column referencing itself. The message suggested a potential problem with the data dictionary, when no

such problem existed. (Bug #12902967)

• InnoDB: For an InnoDB table with a trigger, under the setting innodb_autoinc_lock_mode=1,

sometimes auto-increment values could be interleaved when inserting into the table from two sessions

concurrently. The sequence of auto-increment values could vary depending on timing, leading to data

inconsistency in systems using replication. (Bug #12752572, Bug #61579)

• InnoDB: An ALTER TABLE with both IGNORE and ADD UNIQUE KEY clauses produced an error if

duplicates were found, rather than removing all duplicate rows after the first one. With this fix, the ALTER

TABLE IGNORE syntax automatically enables the ALGORITHM=COPY clause if the ALTER TABLE

statement creates an index. (Bug #12622150)

• InnoDB: When data was removed from an InnoDB table, newly inserted data might not reuse the freed

disk blocks, leading to an unexpected size increase for the system tablespace or .ibd file (depending

on the setting of innodb_file_per_table. The OPTIMIZE TABLE could compact a .ibd file in

some cases but not others. The freed disk blocks would eventually be reused as additional data was

inserted. (Bug #11766634, Bug #59783)

• InnoDB: The CHECK TABLE statement could fail for a large InnoDB table due to a timeout value of 2

hours. For typical storage devices, the issue could occur for tables that exceeded approximately 200

or 350 GB, depending on I/O speed. The fix relaxes the locking performed on the table being checked,

which makes the timeout less likely. It also makes InnoDB recognize the syntax CHECK TABLE QUICK,

which avoids the possibility of the timeout entirely. (Bug #11758510, Bug #50723)

• InnoDB: Full-text search in InnoDB tried to follow foreign key references without keeping track of which

ones it had already seen. With circular and other complex setups, this could loop forever or a very long

time, leading to the appearance of the query thread hanging. (Bug #64274, Bug #13701973)

• Partitioning: If a partitioned table t1 was created using the ROW_FORMAT option, attempting to perform

ALTER TABLE t1 EXCHANGE PARTITION ... WITH TABLE t2 failed with the error Tables have

different definitions even if the definition for table t2 was identical to that for t1. This occurred

because a check was made for an explicit ROW_FORMAT setting in the table definition, and if this was set,

the operation was rejected.

Now in such cases the row format actually used for each table is checked explicitly and the EXCHANGE

PARTITION operation is permitted to execute if both row formats are the same. (Bug #11894100)

• Partitioning: The PARTITION_COMMENT column of the INFORMATION_SCHEMA.PARTITIONS table

truncated partition comments, displaying only the first 80 characters.

As part of the fix for this issue, the maximum length for a partition comment is now set at 1024

characters, and this width is honored by INFORMATION_SCHEMA.PARTITIONS.PARTITION_COMMENT.

(Bug #11748924, Bug #37728)

• Replication: When a complete global transaction spanned relay logs such that only its GTID appeared

in a given relay log while the body of the transaction (including BEGIN and COMMIT statements)

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MySQL 5.6 Release Notes

appeared in the next relay log, the GTID was interpreted incorrectly as belonging to an empty group.

(Bug #14136654)

• Replication: It was possible in some cases when using semisynchronous replication for log rotation to

take place before an ongoing transaction was committed or rolled back. (Bug #14123372)

• Replication: If the relay logs were removed after the server was stopped, without stopping replication

first, the server could not be started correctly. (Bug #14029212, Bug #65152)

References: See also: Bug #13971348.

• Replication: The --bootstrap option for mysqld is used by mysql_install_db when it initializes

the system tables. Now, whenever this option is used, GTIDs (see Replication with Global Transaction

Identifiers) and replication are automatically disabled. (Bug #13992602)

• Replication: It was theoretically possible for concurrent execution of more than one instance of SHOW

BINLOG EVENTS to crash the MySQL Server. (Bug #13979418)

• Replication: If errors were encountered while trying to initialize the mysql.slave_master_info or

mysql.slave_relay_log_info tables, the server refused to start. Now in such cases, the warning

message Error while checking replication metadata. This might also happen when

doing a live upgrade from a version that did not make use of the replication

metadata tables is issued to advise the user that this has happened, but the server is permitted to

continue starting. (Bug #13893363)

• Replication: The text for the error ER_AUTO_POSITION_REQUIRES_GTID_MODE_ON referred to

AUTO_POSITION = 1 although this should be MASTER_AUTO_POSITION = 1. The text has been

corrected. (Bug #13868465)

• Replication: A CHANGE MASTER TO statement could alter the effective value of relay_log_purge.

In addition, the relay_log_recovery system variable is now read-only, and can be changed only by

starting the server with --relay-log-recovery. (Bug #13840948)

• Replication: When binlog_rows_query_log_events = 1 and a statement is written to the binary

log using the row-based logging format, the server generates a an additional log event containing

the text of the original statement. If mysqlbinlog is executed on this log using the --verbose --

verbose, the original statement is printed. To prevent the statement from being executed in addition to

the row event (which would in effect cause the statement to be excuted twice), it is commented out with

a leading # character.

This was implemented with the assumption that such a statement would consist of a single line, which

meant that a statement covering multiple lines was handled incorrectly, in that only the first line of the

statement actually commented out. Now in such cases, every line of the statement is commented out

with a leading #. (Bug #13799555)

• Replication: Queries that were more than 255 characters in length were truncated when viewed in

the output of SHOW BINLOG EVENTS or mysqlbinlog. This was due to the length of the query being

stored in Rows_query_log_events using a single byte. (Bug #13799489)

• Replication: Replication locks and some of the protocols controlling the use of these locks were not well

implemented or enforced. In particular, this fix improves lock handling for statements such as CHANGE

MASTER TO, SHOW SLAVE STATUS, and FLUSH LOGS. (Bug #13779291)

• Replication: When logging transactions that affected both transactional and nontransactional tables, the

following statements could sometimes be written into the binary log in the wrong order or on the wrong

side of a transaction boundary:

• SET,

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MySQL 5.6 Release Notes

• CREATE FUNCTION,

• SHOW BINLOG EVENTS,

• REVOKE ALL PRIVILEGES.

(Bug #13627921)

• Replication: Setting binlog_checksum on the master to a value that was unknown on the slave

caused replication to fail. Now in such cases, replication checksums are disabled on the slave and

replication stops with an appropriate error message. (Bug #13553750, Bug #61096)

• Replication: To provide a crash-safe slave, it was previously necessary to change the storage engine

for the slave_master_info, slave_relay_log_info, and slave_worker_info tables from

MyISAM to InnoDB manually, by issuing ALTER TABLE. To simplify the setup of replication using these

slave log tables, they are now created using the InnoDB storage engine. (Bug #13538891)

• Replication: When the slave had been set using CHANGE MASTER TO with the MASTER_DELAY option

equal to any permitted value greater than zero, then stopped using STOP SLAVE, pointed at the current

relay log position (as shown by SHOW SLAVE STATUS), and started again, START SLAVE failed with

the error Could not initialize master info structure. (Bug #12995174)

• Replication: The --relay-log-space-limit option was sometimes ignored.

More specifically, when the SQL thread went to sleep, it allowed the I/O thread to queue additional

events in such a way that the relay log space limit was bypassed, and the number of events in the queue

could grow well past the point where the relay logs needed to be rotated. Now in such cases, the SQL

thread checks to see whether the I/O thread should rotate and provide the SQL thread a chance to purge

the logs (thus freeing space).

Note that, when the SQL thread is in the middle of a transaction, it cannot purge the logs; it can only ask

for more events until the transaction is complete. Once the transaction is finished, the SQL thread can

immediately instruct the I/O thread to rotate. (Bug #12400313, Bug #64503)

References: See also: Bug #13806492.

• Replication: An event whose length exceeded the size of the master dump thread's

max_allowed_packet caused replication to fail. This could occur when updating many large rows and

using row-based replication.

As part of this fix, a new slave_max_allowed_packet system variable is added, which permits

max_allowed_packet to be exceeded by the slave SQL and I/O threads. Now the size of a packet

transmitted from the master to the slave is checked only against this value, and not against the value of

max_allowed_packet. (Bug #12400221, Bug #60926)

• Replication: Statements using AUTO_INCREMENT, LAST_INSERT_ID(), RAND(), or user variables

could be applied in the wrong context on the slave when using statement-based replication and

replication filtering server options (see How Servers Evaluate Replication Filtering Rules). (Bug

#11761686, Bug #54201)

References: See also: Bug #11754117, Bug #45670, Bug #11746146, Bug #23894.

• Replication: An INSERT into a table that has a composite primary key that includes an

AUTO_INCREMENT column that is not the first column of this composite key is not safe for statement-

based binary logging or replication. Such statements are now marked as unsafe and fail with an error

207

MySQL 5.6 Release Notes

when using the STATEMENT binary logging format. For more information, see Determination of Safe and

Unsafe Statements in Binary Logging, as well as Replication and AUTO_INCREMENT.

Note

This issue does not affect tables using the InnoDB storage engine, since an

InnoDB table with an AUTO_INCREMENT column requires at least one key

where the auto-increment column is the only or leftmost column.

(Bug #11754117, Bug #45670)

References: See also: Bug #11761686, Bug #54201, Bug #11746146, Bug #23894.

• Replication: After upgrading a replication slave to MySQL 5.6.2 or later, enabling the query cache

eventually caused the slave to fail. (Bug #64624, Bug #14005409)

• Microsoft Windows: On Windows, mysqlslap crashed for attempts to connect using shared memory.

(Bug #31173, Bug #11747181, Bug #59107, Bug #11766072)

• Microsoft Windows: For Microsoft Windows, the deprecated MySQL Configuration Wizard is no longer

distributed, and instead the newer MySQL Installer is available and preferred.

• After running ALTER TABLE tbl DISCARD TABLESPACE for an InnoDB table, certain other ALTER

TABLE operations such as renaming the table or rebuilding the primary key could cause a crash. (Bug

#14213568)

• For conditions of the form WHERE p1 AND (p2 OR p3), the optimizer now uses the index merge

access method on (p2,p3) if it is more efficient than a range scan on p1. Previously, index merge was

not considered when a range scan was possible. (Bug #14208922)

• Error messages that should have said "YEAR(2)" said "YEAR(0)" instead. (Bug #14167585)

• For debug builds, INSERT IGNORE INTO ... SELECT that selected more than max_join_size

rows could raise an assertion. (Bug #14145442)

• With logging of the general query log to a table, logging was disabled within a read-only transaction

because write lock acquisition on the log table was blocked. (Bug #14136866)

• The ARCHIVE storage engine could not be built unless the Performance Schema was also built. (Bug

#14116252)

• If a nonexistent page was requested to be loaded into the InnoDB buffer pool by the

innodb_buffer_pool_load_at_startup configuration option, a subsequent shutdown operation

could hang. (Bug #14106082)

• In debug builds, the server failed to check for error status from the storage engine and raised an

assertion. (Bug #14101852)

• In debug builds, warnings occurring during creation of an InnoDB table with ROW_FORMAT=DYNAMIC

and innodb_file_per_table disabled could raise an assertion. (Bug #14101563)

• Derived tables and tables created with CREATE TABLE ... SELECT using the output from single-row

queries with NULL in the first column could change the value to 0. (Bug #14069831)

• Incorrect assessment of column nullability for a subquery result within a trigger could cause “column

cannot be null” errors. (Bug #14069810, Bug #14005353)

• The Performance Schema did not generate consistent digest values for CALL statements. (Bug

#14069132)

208

MySQL 5.6 Release Notes

• The LooseScan semijoin strategy could fail to remove duplicates from the result set. (Bug #14053325)

• Certain arguments to RPAD() could lead to “uninitialized variable” warnings. (Bug #14039955)

• For debug builds compiled with gcov, tests that used DBUG_SUICIDE lost gcov data. (Bug #14028421)

• When the index enforcing a foreign key constraint was dropped while foreign_key_checks=0,

further operations involving the foreign key column could cause a serious error after the

foreign_key_checks option was re-enabled. (Bug #14025221)

• Mishandling of failed internal commits in administrative statements such as ANALYZE TABLE could

cause an assertion to be raised. (Bug #14001091)

• Improper calculation of decimals for TIME values given as arguments to IF() or IFNULL() could cause

a server crash. (Bug #13988413, Bug #14042545)

• Some arguments to MAKETIME() could cause a buffer overflow. (Bug #13982125)

• For debug builds, conversion of a double-precision value to the lldiv_t type could raise an assertion.

(Bug #13976233)

• Mishandling of failure during multiple-table UPDATE IGNORE statements could cause an assertion to be

raised. (Bug #13974815)

• Queries that grouped by an outer BLOB column in a subquery caused a server crash. (Bug #13966809)

• Selecting MIN() or MAX() from a left or right join involving an INFORMATION_SCHEMA table could

cause a server crash. (Bug #13966514)

• Queries containing references to user variables were not written to the general query log with some

rewriting, not as received. (Bug #13958454)

• For debug builds, the optimizer could change the query plan when checking sort order and return

incorrect results. (Bug #13949068)

• An infinite thread loop could develop within Performance Schema, causing the server to become

unresponsive. (Bug #13898343)

• Overhead for Performance Schema table aggregation operations was excessive. (Bug #13862186)

• The version_compile_machine system variable sometimes did not include the value 64 for server

binaries compiled on a 64-bit system. (Bug #13859866)

• With subquery materialization enabled, some queries with a subquery in the HAVING clause caused a

server crash. (Bug #13848789)

• When the InnoDB persistent statistics feature was turned on, an ALTER TABLE statement on an

InnoDB table with delete-marked records could cause a crash (non-debug builds) or assertion error

(debug builds). (Bug #13838962, Bug #13867915)

• In bootstrap mode, the server signal handler thread did not shut down if the server aborted early. (Bug

#13837221)

• Some errors in MySQL 5.6 had different numbers than in MySQL 5.5. (Bug #13833438)

• If KILL QUERY interrupted an INSERT or UPDATE that had the IGNORE modifier, OK was incorrectly

returned to the client rather than an error code. Now an error (“Query execution was interrupted”) is

returned instead. (Bug #13822652)

209

MySQL 5.6 Release Notes

• If KILL QUERY interrupted a statement during derived table materialization, the server crashed later

trying to read the nonexistent materialized table. (Bug #13820776)

• Incorrect cost calculations for two-table joins could lead to incorrect join order. (Bug #13810048)

References: This issue is a regression of: Bug #26106.

• The Performance Schema stored identifiers in digest tables as utf8 without converting them from the

original character set first. (Bug #13809293)

• Incorrect stored program caching could cause statements within a stored program that included a GROUP

BY clause to return different results across multiple program invocations. (Bug #13805127)

• For comparison of a temporal value to and indexed character column, the optimizer could apply the

range access method and thus perform an indexed search that found only literal matches. This is

incorrect because MySQL permits a variety of delimiters in temporal values represented as strings. (Bug

#13803810)

• Several clarifications were made to optimizer trace output. (Bug #13799348)

• viosslfactories did not compile on Oracle Linux 6.0 with CMake options -DWITH_SSL=system and

-DWITH_DEBUG=1. (Bug #13799126)

• In debug builds, a race condition in a signal handler during shutdown caused a server crash. (Bug

#13793813)

• A prepared statement that referenced views and were executed using semijoin transformation could

return different results for different executions. (Bug #13773979)

References: See also: Bug #14641759.

• Outer join queries with ALL could return incorrect results because the optimizer incorrectly rewrote them

to use inner join. (Bug #13735712)

• (a,b) IN (SELECT c,d FROM t1 WHERE ...) could produce incorrect results if t1 had an index

on (c, d) and c or d contained NULL values. (Bug #13731417)

• For open ranges that effectively resulted in a full index scan, the optimizer did not discard the range

predicate as unneeded. (Bug #13731380)

• The range optimizer sometimes did not treat equivalent expressions the same, depending on the order

of the operands. For example, it could treat a <= b and b >= a differently. (Bug #13701206)

• With semijoin optimization enabled, an assertion was raised for queries for which the number of tables

was greater than the search depth. (Bug #13685026)

• Truncating a table partition did not invalidate queries in the query cache that used the table. (Bug

#13485448)

• Setting max_sort_length to small values could cause a server crash. (Bug #13485416)

• A query executed with literal values in the WHERE clause could return results different from the same

query written to select the same literal values from a separate table using a SELECT statement in the

WHERE clause. (Bug #13468414)

• Condition handler code could assume that after handler execution, control would pass up a single level

to the parent, sometimes leading to a server crash. (Bug #13431226)

• If a GROUP_CONCAT() result was calculated using intermediate results (for example, if ORDER BY or

DISTINCT was present), individual intermediate results were each truncated to a maximum of 64K,

210

MySQL 5.6 Release Notes

even if the group_concat_max_len system variable was set to a larger value. Now the length of any

intermediate result and the final result are controlled by the group_concat_max_len value. (Bug

#13387020, WL #6098)

• Queries with ALL subquery predicates could return incorrect results due to a faulty query transformation.

(Bug #13330886)

• Switching between index scans and random scans using the HANDLER interface could result in failure of

the interface to properly reinitialize scans. (Bug #13008220)

• The presence of a file named .empty in the test database prevented that database from being

dropped. (Bug #12845091)

• For queries with ORDER BY COUNT(*) and LIMIT, the optimizer could choose an execution plan that

produced incorrect results. (Bug #12713907)

• For some subqueries that should be executed using a range scan on a nonprimary index and required

use of filesort, only the first execution of the subquery was done as a range scan. All following

executions were done as full table scans, resulting in poor performance. In addition, if index condition

pushdown was used, incorrect results could be returned. (Bug #12667154)

• IPv6 functions such as IS_IPV6() produced Valgrind warnings with arguments that used a multibyte

character set. (Bug #12635232, Bug #14040277)

• Queries that used STRAIGHT_JOIN and were executed using Multi-Range Read optimization could

result in a memory leak. (Bug #12365385)

• Overhead for the Performance Schema was reduced. (Bug #12346211)

• IN subqueries that used a variance or standard deviation aggregate function could return a different

result depending on whether the optimizer_switch materialization flag was enabled.

Note

Those aggregate functions may now return a result with a different number of

decimals from previously.

(Bug #11766758)

• On Windows, initial database creation failed during bootstrapping. (Bug #11766342)

• A regression bug in the optimizer could cause excessive disk usage for UPDATE statements on InnoDB

tables. For tables created with innodb_file_per_table enabled, OPTIMIZE TABLE can be used

to recover excessive space used. For tables created in the InnoDB system tablespace,it is necessary

to perform a dump and restore into a new instance of the system tablespace. (Bug #65745, Bug

#14248833)

• Parse errors that occurred while loading UCA or LDML collation descriptions were not written to the error

log. (Bug #65593, Bug #14197426)

• Incorrect metadata could be produced for columns returned from some views. (Bug #65379, Bug

#14096619)

• If an account had a nonzero MAX_USER_CONNECTIONS value, that value was not always respected.

(Bug #65104, Bug #14003080)

• When an ALTER TABLE operation was performed with an invalid foreign key constraint, the error

reported was ER_CANT_CREATE_TABLE rather than ER_CANNOT_ADD_FOREIGN. (Bug #64617, Bug

#13840553)

211

MySQL 5.6 Release Notes

• SAVEPOINT statements were incorrectly disallowed within XA transactions. (Bug #64374, Bug

#13737343)

References: See also: Bug #11766752.

• The server crashed at shutdown if the slow query log file was a named pipe. (Bug #64345, Bug

#13733221)

• Some Czech error messages contained invalid characters. (Bug #64310, Bug #13726075)

• With lower_case_table_names=2 on systems with case-insensitive file systems such as Windows or

OS X, CREATE TABLE ... LIKE did not preserve lettercase of the destination table name as given in

the statement. (Bug #64211, Bug #13702397)

• File access by the ARCHIVE storage engine was not instrumented and thus not shown in Performance

Schema tables. (Bug #63340, Bug #13417440)

• The Performance Schema incorrectly displayed some backslashes in Windows file names (by doubling

them). (Bug #63339, Bug #13417446)

• An inappropriate mutex was used to protect random number generation, causing contention during

connect operations. (Bug #62282, Bug #12951609)

• mysql_store_result() and mysql_use_result() are not for use with prepared statements and

are not intended to be called following mysql_stmt_execute(), but failed to return an error when

invoked that way in libmysqld. (Bug #62136, Bug #13738989)

References: See also: Bug #47485.

• Under some conditions, the effect of RENAME USER was not recognized until FLUSH PRIVILEGES was

used (which should not be necessary). (Bug #61865, Bug #12766319)

• If the bind_address system variable was given a host name value and the host name resolved to

more than one IP address, the server failed to start. For example, with bind_address=localhost,

if localhost resolved to both 127.0.0.1 and ::1, startup failed. Now the server prefers the IPv4

address in such cases. (Bug #61713, Bug #12762885)

• SHOW TABLES was very slow unless the required information was already in the disk cache. (Bug

#60961, Bug #12427262)

• On Windows, the mysql client crashed when invoked using its full path name. (Bug #60858, Bug

#12402882)

• Sessions could end up deadlocked when executing a combination of SELECT, DROP TABLE, KILL, and

SHOW ENGINE INNODB STATUS. (Bug #60682, Bug #12636001)

• For debug builds, errors occurring during processing of INSERT DELAYED statements could crash the

server. (Bug #60114, Bug #11827404)

• Using CONCAT() to construct a pattern for a LIKE pattern match could result in memory corrupting and

match failure. (Bug #59140, Bug #11766101)

• Due to a race condition, it was possible for two threads to end up with the same query ID for different

queries. (Bug #58785, Bug #11765785)

• For queries with range predicates, the optimizer could miscalculate the number of key parts used,

possibly leading to a server crash. (Bug #58731, Bug #11765737)

212

MySQL 5.6 Release Notes

• SHOW statements treated stored procedure, stored function, and event names as case sensitive. (Bug

#56224, Bug #11763507)

• mysqlbinlog exited with no error code if file write errors occurred. (Bug #55289, Bug #11762667)

• yaSSL rejected valid SSL certificates that OpenSSL accepts. (Bug #54348, Bug #11761822)

• If the server held a global mutex while doing network I/O, client disconnections could be slow. (Bug

#53096, Bug #11760669)

• A multiple-table UPDATE with the IGNORE keyword resulted in an inappropriate and not meaningful Got

error 0 from storage engine message. (Bug #49539, Bug #11757486)

• When dumping the mysql database, mysqldump did not include the general_log and

slow_query_log tables because they cannot be locked. This caused a problem after reloading the

dump file if that file contained a DROP DATABASE statement for the mysql database: The database no

longer contained the log tables and attempts to log to them failed. Now mysqldump includes statements

to re-create the general_log and slow_query_log tables so that they exist after loading the dump

file. Log table contents still are not dumped. (Bug #45740, Bug #11754178)

• When a query was killed, the error code was not always properly propagated up through the server

code. (Bug #43353, Bug #11752226)

• The optimizer could chose a worse execution plan for a condition that used a quoted number compared

to the unquoted number. (Bug #43319, Bug #11752201)

• Queries that used WHERE (col1, col2) IN ((const, const)) were optimized for SELECT, but

not for DELETE or UPDATE. (Bug #43187, Bug #11752097)

• For ALTER TABLE with the IGNORE keyword, IGNORE is now part of the information provided to the

storage engine. It is up to the storage engine whether to use this when choosing between the in-place

or copy algorithm for altering the table. For InnoDB index operations, IGNORE is not used if the index is

unique, so the copy algorithm is used. (Bug #40344, Bug #11750045)

• LEFT JOIN on derived tables was very slow. This is now addressed through the use of subquery

materialization. (Bug #34364, Bug #11747876)

• MySQL was overly agressive in enforcing the NO_ZERO_DATE and NO_ZERO_IN_DATE SQL modes

for default values in column definitions for CREATE TABLE and ALTER TABLE statements. Previously,

default dates that were invalid with those SQL modes enabled produced an error, even when strict

mode was not enabled. Now with NO_ZERO_DATE or NO_ZERO_IN_DATE enabled, invalid default dates

produce a warning if strict SQL mode is not enabled, and an error if strict mode is enabled. (Bug #34280,

Bug #11747847)

• Redundant “Specified key was too long” messages could be produced by index-creation operations.

(Bug #31149, Bug #11747177)

• Code for the storage engine API did not check the return value from the ha_rnd_init(),

ha_index_init(), and index_init() functions. (Bug #26040, Bug #11746399, Bug #54166, Bug

#11761652)

• For table or database names that are longer than 64 characters, the error “Incorrect table name” was

returned rather than “Identifier too long”. (Bug #25168, Bug #11746295)

• During the startup process, mysqld could incorrectly remove the PID file of an already running mysqld.

(Bug #23790, Bug #11746142)

References: See also: Bug #14726272.

213

MySQL 5.6 Release Notes

• Using ALTER TABLE to add a TIMESTAMP column containing DEFAULT CURRENT_TIMESTAMP in the

definition resulted in a column containing '0000-00-00 00:00:00', not the current timestamp. (Bug

#17392, Bug #11745578)

Changes in MySQL 5.6.5 (2012-04-10, Milestone 8)

Note

This is a milestone release, for use at your own risk. Upgrades between milestone

releases (or from a milestone release to a GA release) are not supported.

Significant development changes take place in milestone releases and you may

encounter compatibility issues, such as data format changes that require attention

in addition to the usual procedure of running mysql_upgrade. For example, you

may find it necessary to dump your data with mysqldump before the upgrade and

reload it afterward. (Making a backup before the upgrade is a prudent precaution in

any case.)

Beginning with MySQL 5.6.5, Oracle no longer provides binaries for OS X 10.5. This aligns with Apple no

longer providing updates or support for this platform.

• Data Type Notes

• Replication with GTIDs

• Host Cache Notes

• Optimizer Notes

• Performance Schema Notes

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

Data Type Notes

• Previously, at most one TIMESTAMP column per table could be automatically initialized or updated to the

current date and time. This restriction has been lifted. Any TIMESTAMP column definition can have any

combination of DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP clauses. In

addition, these clauses now can be used with DATETIME column definitions. For more information, see

Automatic Initialization and Updating for TIMESTAMP and DATETIME. (WL #5874)

Replication with GTIDs

• Important Change; Replication: This release introduces global transaction identifiers (GTIDs) for

MySQL Replication. A GTID is a unique identifier that is assigned to each transaction as it is committed;

this identifier is unique on the MySQL Server where the transaction originated, as well as across all

MySQL Servers in a given replication setup. Because GTID-based replication depends on tracking

transactions, it cannot be employed with tables that employ a nontransactional storage engine such as

MyISAM; thus, it is currently supported only with InnoDB tables.

Because each transaction is uniquely identified, it is not necessary when using GTIDs to specify

positions in the master's binary log when starting a new slave or failing over to a new master. This

is reflected in the addition of a new MASTER_AUTO_POSITION option for the CHANGE MASTER TO

214

MySQL 5.6 Release Notes

statement which takes the place of the MASTER_LOG_FILE and MASTER_LOG_POS options when

executing this statement to prepare a MySQL Server to act as a replication slave.

To enable GTIDs on a MySQL Server, the server must be started with the options --gtid-mode=ON

--disable-gtid-unsafe-statements --log-bin --log-slave-updates. These options are

needed whether the server acts as a replication master or as a replication slave; the --gtid-mode and

--disable-gtid-unsafe-statements options are new in this release. Once the master and slave

have each been started with these options, it is necessary only to issue a CHANGE MASTER TO ...

MASTER_AUTO_POSITION=1 followed by START SLAVE on the slave to start replication.

A number of new server system variables have also been added for monitoring GTID usage. For more

information about these options and variables, see Global Transaction ID Options and Variables.

As part of these changes, three new mysqlbinlog options—--include-gtids, --exclude-gtids,

and --skip-gtids—have been added for reading binary logs produced when the server participates in

replication with GTIDs.

Important

Due to an issue discovered just prior to release, you cannot import a dump made

using mysqldump from a MySQL 5.5 server to a MySQL 5.6.5 server and then

use mysqlupgrade on the MySQL 5.6.5 server while GTIDs are enabled; doing

so makes it impossible to connect to the server normally following the upgrade.

Instead, you should import the dump and run mysqlupgrade while the MySQL

5.6.5 server is running with --gtid-mode=OFF, then restart it with --gtid-

mode=ON. (Bug #13833710) (mysqlupgrade can be executed when the server

is running with --gtid-mode set either to OFF, or to ON.)

For additional information about GTIDs and setting up GTID-based replication, see Replication with

Global Transaction Identifiers. (WL #3584)

Host Cache Notes

• MySQL now provides improved access to the host cache, which contains client IP address and host

name information and is used to avoid DNS lookups, as well as more information about the causes of

errors that occur when clients connect to the server. These changes have been implemented:

• A new Performance Schema host_cache table exposes the contents of the host cache so that it

can be examined using SELECT statements. Access to host cache contents makes it possible to

answer questions such as how many hosts are cached, what kinds of connection errors are occurring

for which hosts, or how close host error counts are to reaching the max_connect_errors system

variable limit. The Performance Schema must be enabled or this table is empty.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate this change into the performance_schema database.

• The host cache has additional counters to track errors that do apply to specific IP addresses.

• The host cache size now is configurable using the host_cache_size system variable. This variable

also controls the maximum size of the host_cache table because that table is the cache visible

representation. Setting the size to 0 disables the host cache. This is similar to disabling the cache

by starting the server with --skip-host-cache, but using host_cache_size is more flexible

because it can also be used to resize, enable, and disable the host cache at runtime, not just at server

startup. If you start the server with --skip-host-cache, the host cache cannot be re-enabled at

runtime.

215

MySQL 5.6 Release Notes

• New Connection_errors_xxx status variables provide information about connection errors that do

not apply to specific client IP addresses.

For more information, see DNS Lookups and the Host Cache, and The host_cache Table. (Bug #22821,

Bug #24906, Bug #45817, Bug #59404, Bug #11746048, Bug #11746269, Bug #11754244, Bug

#11766316, WL #5259)

Optimizer Notes

• Reporting of how to sort a result set in EXPLAIN has been improved for some statements. This sorting

decision could be reported incorrectly, causing Using filesort or Using temporary to be reported

when they should not have been or vice versa. This could occur for statements that included index hints,

that had the form SELECT SQL_BIG_RESULT ... GROUP BY, that used SQL_CALC_FOUND_ROWS

with LIMIT, or that used GROUP BY, ORDER BY, and LIMIT. (Bug #11744768, Bug #1560, WL #5558)

• These query optimizer improvements were implemented:

• The EXPLAIN statement now can produce output in JSON format. To select this, use EXPLAIN

FORMAT = JSON explainable_stmt syntax. With FORMAT = JSON, the output includes regular

EXPLAIN information, as well as extended and partition information.

Traditional EXPLAIN output has also changed so that empty columns contain NULL rather the empty

string. In addition, UNION RESULT rows have Using filesort in the Extra column because a

temporary table is used to buffer UNION results.

To work for both Optimizer Trace and JSON-format EXPLAIN output, the end_marker parameter for

the optimizer_trace system variable has been moved to a separate end_markers_in_json

system variable. This is an incompatible change to the optimizer_trace variable. For more

information, see MySQL Internals: Tracing the Optimizer.

• The optimizer tries to find the best query execution plan by beginning with the most promising table

and recursively adding to the plan the most promising of the remaining tables. Partial execution plans

with a higher cost than an already found plan are pruned. The optimizer now attempts to improve

the order in which it adds tables to the plan, resulting in a reduction of the number of partial plans

considered.

Queries that are likely to have improved performance are joins of many tables, where most tables use

eq_ref or ref join types (as indicated by EXPLAIN output).

A new status variable, Last_query_partial_plans, counts the number of iterations the optimizer

makes in execution plan construction for the previous query.

• The optimizer uses semijoin and materialization strategies to optimize subquery execution. See

Optimizing Subqueries with Semijoin Transformations, and Optimizing Subqueries with Materialization.

In addition, the Batched Key Access (BKA) Join and Block Nested-Loop (BNL) Join algorithms used

for inner join and outer join operations have been extended to support semijoin operations. For more

information, see Block Nested-Loop and Batched Key Access Joins.

Several flags have been added to the optimizer_switch system variable to enable control over

semijoin and subquery materialization strategies. The semijoin flag controls whether semijoins are

used. If it is set to on, the firstmatch and loosescan flags enable finer control over the permitted

semijoin strategies. The materialization flag controls whether subquery materialization is used. If

semijoin and materialization are both on, semijoins also use materialization where applicable.

These flags are on by default. See Switchable Optimizations.

216

MySQL 5.6 Release Notes

• For expressions such as col_name IN(values) that compare a column to a list of values, the

optimizer previously made row estimates using index dives for each value in the list. This becomes

inefficient as the number of values becomes large. The optimizer now can make row estimates for

such expressions using index statistics instead, which is less accurate but quicker for a large number

of values. The point at which the optimizer switches from index dives to index statistics is configurable

using the new eq_range_index_dive_limit system variable. For more information, see Equality

Range Optimization of Many-Valued Comparisons.

(WL #5729, WL #5855, WL #5957, WL #6158)

Performance Schema Notes

• The Performance Schema has these additions:

• The Performance Schema now has a host_cache table that exposes the contents of the host

cache so that it can be examined using SELECT statements. See Host Cache Notes elsewhere in this

changelog.

• The Performance Schema now maintains statement digest information. This normalizes and groups

statements with the same “signature” and permits questions to be answered about the types of

statements the server is executing and how often they occur.

• A statement_digest consumer in the setup_consumers table controls whether the

Performance Schema maintains digest information.

• The statement event tables (events_statements_current, events_statements_history,

and events_statements_history_long) have DIGEST and DIGEST_TEXT columns that

contain digest MD5 values and the corresponding normalized statement text strings.

• A events_statements_summary_by_digest table provides aggregated statement digest

information.

For more information, see The host_cache Table, Performance Schema Statement Event Tables, and

Statement Summary Tables.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the performance_schema database. (WL #5767)

Security Notes

• Passwords stored in the older hash format used before MySQL 4.1 are less secure than passwords

that use the native password hashing method and should be avoided. Pre-4.1 passwords and the

mysql_old_password authentication plugin are now deprecated. To prevent connections using

accounts that have pre-4.1 password hashes, the secure_auth system variable is now enabled by

default. (To permit connections for accounts that have such password hashes, start the server with --

secure_auth=0.) (Bug #13586336)

• MySQL client programs now issue a warning if a password is given on the command line that this can be

insecure.

Functionality Added or Changed

• Incompatible Change: The obsolete OPTION modifier for the SET statement has been removed. (WL

#5185, WL #6311)

217

MySQL 5.6 Release Notes

• InnoDB: --ignore-builtin-innodb is now ignored if used. (Bug #13586262)

• OS X; Microsoft Windows: A new CMake option, MYSQL_PROJECT_NAME, can be set on Windows or

OS X to be used in the project name. (Bug #13551687)

• Microsoft Windows: A new server option, --slow-start-timeout, controls the Windows service

control manager's service start timeout. The value is the maximum number of milliseconds that the

service control manager waits before trying to kill the MySQL service during startup. The default value is

15000 (15 seconds). If the MySQL service takes too long to start, you may need to increase this value. A

value of 0 means there is no timeout. (Bug #45546, Bug #11754011)

• The MySQL-shared-compat RPM package enables users of Red Hat-provided mysql-*-5.1 RPM

packages to migrate to Oracle-provided MySQL-*-5.5 packages. MySQL-shared-compat now

replaces the Red Hat mysql-libs package by replacing libmysqlclient.so files of the latter

package, thus satisfying dependencies of other packages on mysql-libs. This change affects only

users of Red Hat (or Red Hat-compatible) RPM packages. Nothing is different for users of Oracle RPM

packages. (Bug #13867506)

• Temporary tables for INFORMATION_SCHEMA queries now use dynamic MyISAM row format if they

contain sufficiently large VARCHAR columns, resulting in space savings. (Bug #13627632)

• As of MySQL 5.5.3, the LOW_PRIORITY modifier for LOCK TABLES ... LOW_PRIORITY WRITE has

no effect. This modifier is now deprecated. Its use should be avoided and now produces a warning. Use

LOCK TABLES ... WRITE instead. (Bug #13586314)

• If the log_queries_not_using_indexes system variable is enabled, slow queries that do not use

indexes are written to the slow query log. In this case, it is now possible to put a logging rate limit on

these queries by setting the new log_throttle_queries_not_using_indexes system variable,

so that the slow query log does not grow too quickly. By default, this variable is 0, which means there

is no limit. Positive values impose a per-minute limit on logging of queries that do not use indexes. The

first such query opens a 60-second window within which the server logs queries up to the given limit,

then suppresses additional queries. If there are suppressed queries when the window ends, the server

logs a summary that indicates how many there were and the aggregate time spent in them. The next 60-

second window begins when the server logs the next query that does not use indexes. (Bug #55323,

Bug #11762697)

• Several subquery performance issues were resolved through the implementation of semijoin subquery

optimization strategies. See Optimizing Subqueries with Semijoin Transformations. (Bug #47914, Bug

#11756048, Bug #58660, Bug #11765671, Bug #10815, Bug #11745162, Bug #9021, Bug #13519134,

Bug #48763, Bug #11756798, Bug #25130, Bug #11746289)

• The mysql client now supports an --init-command=str option. The option value is an SQL

statement to execute after connecting to the server. If auto-reconnect is enabled, the statement is

executed again after reconnection occurs. (Bug #45634, Bug #11754087)

• New utf8_general_mysql500_ci and ucs2_general_mysql500_ci collations have been

added that preserve the behavior of utf8_general_ci and ucs2_general_ci from versions of

MySQL previous to 5.1.24. Bug #27877 corrected an error in the original collations but introduced an

incompatibility for columns that contain German 'ß' LATIN SMALL LETTER SHARP S. (As a result

of the fix, that character compares equal to characters with which it previously compared different.) A

symptom of the problem after upgrading to MySQL 5.1.24 or newer from a version older than 5.1.24 is

that CHECK TABLE produces this error:

Table upgrade required.

218

MySQL 5.6 Release Notes

Please do "REPAIR TABLE `t`" or dump/reload to fix it!

Unfortunately, REPAIR TABLE could not fix the problem. The new collations permit older tables created

before MySQL 5.1.24 to be upgraded to current versions of MySQL.

To convert an affected table after a binary upgrade that leaves the table files in place, alter the table to

use the new collation. Suppose that the table t1 contains one or more problematic utf8 columns. To

convert the table at the table level, use a statement like this:

ALTER TABLE t1

CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_mysql500_ci;

To apply the change on a column-specific basis, use a statement like this (be sure to repeat the column

definition as originally specified except for the COLLATE clause):

ALTER TABLE t1

MODIFY c1 CHAR(N) CHARACTER SET utf8 COLLATE utf8_general_mysql500_ci;

To upgrade the table using a dump and reload procedure, dump the table using mysqldump, modify the

CREATE TABLE statement in the dump file to use the new collation, and reload the table.

After making the appropriate changes, CHECK TABLE should report no error. (Bug #43593, Bug

#11752408)

References: See also: Bug #27877.

• The SET TRANSACTION and START TRANSACTION statements now support READ WRITE and READ

ONLY modifiers to set the transaction access mode for tables used in transactions. The default mode is

read/write, which is the same mode as previously. Read/write mode now may be specified explicitly with

the READ WRITE modifier. Using READ ONLY prohibits table changes and may enable storage engines

to make performance improvements that are possible when changes are not permitted.

In addition, the new --transaction-read-only option and tx_read_only system variable permit

the default transaction access mode to be set at server startup and runtime.

For more information, see SET TRANSACTION Statement, and START TRANSACTION, COMMIT, and

ROLLBACK Statements. (WL #5968)

• MySQL distributions no longer include the GPL readline input-editing library. This results in simpler

maintenance and support, and simplifies licensing considerations.

Bugs Fixed

• Incompatible Change; Replication: CHANGE MASTER TO statements were written into the error log

using quoted numeric values, although the syntax for this statement does not allow such option values to

be quoted. This meant that such statements could not be copied from the error log and re-run verbatim.

Now CHANGE MASTER TO statements are written to the error log without the extraneous quotation

marks, and so are syntactically correct as logged.

• Incompatible Change: A change in MySQL 5.6.3 caused LAST_DAY() to be more strict and reject

incomplete dates with a day part of zero. For this function, a nonzero day part is not necessary, so the

change has been reverted. (Bug #13458237)

• Important Change; InnoDB: When a row grew in size due to an UPDATE operation, other (non-

updated) columns could be moved to off-page storage so that information about the row still fit within

the constraints of the InnoDB page size. The pointer to the new allocated off-page data was not set

up until the pages were allocated and written, potentially leading to lost data if the system crashed

while the column was being moved out of the page. The problem was more common with tables using

219

MySQL 5.6 Release Notes

ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED along with the Barracuda file format, particularly

with the innodb_file_per_table setting enabled, because page allocation operations are more

common as the .ibd tablespace files are extended. Still, the problem could occur with any combination

of InnoDB version, file format, and row format.

A related issue was that during such an UPDATE operation, or an INSERT operation that reused a delete-

marked record, other transactions could see invalid data for the affected column, regardless of isolation

level.

The fix corrects the order of operations for moving the column data off the original page and replacing it

with a pointer. Now if a crash occurs at the precise moment when the column data is being transferred,

the transfer will not be re-run during crash recovery.

In MySQL 5.1, this fix applies to the InnoDB Plugin, but not the built-in InnoDB storage engine. (Bug

#13721257, Bug #12612184, Bug #12704861)

• Important Change; Partitioning: The query cache did not always function correctly with partitioned

tables in a transactional context. For this reason, the query cache is now disabled for any queries using

partitioned tables, and such queries can no longer be cached. For more information, see Restrictions

and Limitations on Partitioning. (Bug #11761296, Bug #53775)

• Important Change; Replication: The CHANGE MASTER TO statement was not checked for invalid

characters in values for options such as MASTER_HOST and MASTER_USER. In addition, when the

server was restarted, a value containing certain characters was trimmed, causing the loss of its original

value. Now such values are validated, and in cases where the value contains invalid characters,

including linefeed (\n or 0x0A) characters, the statement fails with an error (ER_MASTER_INFO). (Bug

#11758581, Bug #50801)

• Important Change; Replication: Moving the binary log file, relay log file, or both files to a new location,

then restarting the server with a new value for --log-bin, --relay-log, or both, caused the server to

abort on start. This was because the entries in the index file overrode the new location. In addition, paths

were calculated relative to datadir (rather than to the --log-bin or --relay-log values).

The fix for this problem means that, when the server reads an entry from the index file, it now checks

whether the entry contains a relative path. If it does, the relative part of the path is replaced with the

absolute path set using the --log-bin or --relay-log option. An absolute path remains unchanged;

in such a case, the index must be edited manually to enable the new path or paths to be used. (Bug

#11745230, Bug #12133)

• Performance; InnoDB: The optimizer now takes into account InnoDB page sizes other than 16KB,

which can be configured with the innodb_page_size option when creating a MySQL instance. This

change improves the estimates of I/O costs for queries on systems with non-default InnoDB page sizes.

(Bug #13623078)

• Performance; InnoDB: Memory allocation for InnoDB tables was reorganized to reduce the memory

overhead for large numbers of tables or partitions, avoiding situations where the “resident set size” could

grow regardless of FLUSH TABLES statements. The problem was most evident for tables with large row

size. Some of the memory that was formerly allocated for every open table is now allocated only when

the table is modified for the first time. (Bug #11764622, Bug #57480)

• Performance: Temporary MyISAM tables (unlike normal MyISAM tables) did not use the dynamic row

format when they contained VARCHAR columns, resulting in larger temporary files (and more file I/O) than

necessary. Dynamic row format now is used, which results in smaller tables that are faster to process.

(Bug #13350136, Bug #78840, Bug #22023218)

• InnoDB: An erroneous assertion could occur, in debug builds only, when creating an index on a column

containing zero-length values (that is, ''). (Bug #13654923)

220

MySQL 5.6 Release Notes

• InnoDB: A DDL operation such as ALTER TABLE ... ADD COLUMN could stall, eventually timing out

with an Error 1005: Can't create table message referring to fil_rename_tablespace.

(Bug #13636122, Bug #62100, Bug #63553)

• InnoDB: If InnoDB was started with innodb_force_recovery set to a value of 3 or 4, and there are

transactions to roll back, normal shutdown would hang waiting for those transactions to complete. Now

the shutdown happens immediately, without rolling back any transactions, because nonzero values for

innodb_force_recovery are only appropriate for troubleshooting and diagnostic purposes. (Bug

#13628420)

• InnoDB: The MySQL server could hang in some cases if the configuration option

innodb_use_native_aio was turned off. (Bug #13619598)

• InnoDB: A Valgrind error was fixed in the function os_aio_init(). (Bug #13612811)

• InnoDB: The configuration option innodb_sort_buf_size was renamed to

innodb_sort_buffer_size for consistency. This work area is used while creating an InnoDB index.

(Bug #13610358)

• InnoDB: The server could crash when creating an InnoDB temporary table under Linux, if the $TMPDIR

setting points to a tmpfs filesystem and innodb_use_native_aio is enabled, as it is by default in

MySQL 5.5.4 and higher. The entry in the error log looked like:

101123 2:10:59 InnoDB: Operating system error number 22 in a file operation.

InnoDB: Error number 22 means 'Invalid argument'.

The crash occurred because asynchronous I/O is not supported on tmpfs in some Linux kernel versions.

The workaround was to turn off the innodb_use_native_aio setting or use a different temporary

directory. The fix causes InnoDB to turn off the innodb_use_native_aio setting automatically if

it detects that the temporary file directory does not support asynchronous I/O. (Bug #13593888, Bug

#11765450, Bug #58421)

• InnoDB: During startup, the status variable Innodb_buffer_pool_dump_status could be empty for

a brief time before being initialized to the correct value not started. (Bug #13513676)

• InnoDB: Valgrind errors when referencing the internal function buf_LRU_scan_and_free_block()

were fixed. (Bug #13491704)

• InnoDB: The MySQL error log could contain messages like:

InnoDB: Ignoring strange row from mysql.innodb_index_stats WHERE ...

The fix makes the contents of the innodb_index_stats and innodb_table_stats tables case-

sensitive, to properly distinguish the statistics for tables whose names differ only in lettercase. Other

cases were fixed where the wrong name could be selected for an index while retrieving persistent

statistics. (Bug #13432465)

• InnoDB: References to C preprocessor symbols and macros HAVE_purify,

UNIV_INIT_MEM_TO_ZERO, and UNIV_SET_MEM_TO_ZERO were removed from the InnoDB source

code. They were only used in debug builds instrumented for Valgrind. They are replaced by calls to the

UNIV_MEM_INVALID() macro. (Bug #13418934)

• InnoDB: The MySQL server could halt with an assertion error:

InnoDB: Failing assertion: page_get_n_recs(page) > 1

Subsequent restarts could fail with the same error. The error occurred during a purge operation

involving the InnoDB change buffer. The workaround was to set the configuration option

innodb_change_buffering=inserts. (Bug #13413535, Bug #61104)

221

MySQL 5.6 Release Notes

• InnoDB: A discrepancy could arise between the number of available InnoDB undo logs and the number

of undo logs that were currently active. Now the innodb_undo_logs system variable reports the

number of active undo logs, and the new Innodb_available_undo_logs status variable reports the

total number of undo logs. (Bug #13255225)

• InnoDB: When doing a live downgrade from MySQL 5.6.4 or later, with innodb_page_size set to a

value other than 16384, now the earlier MySQL version reports that the page size is incompatible with

the older version, rather than crashing or displaying a “corruption” error. (Bug #13116225)

• InnoDB: Certain CREATE TABLE statements could fail for InnoDB child tables containing

foreign key definitions. This problem affected Windows systems only, with the setting

lower_case_table_names=0. It was a regression from MySQL bug #55222. (Bug #13083023, Bug

#60229)

• InnoDB: If the server crashed during a TRUNCATE TABLE or CREATE INDEX statement for an InnoDB

table, or a DROP DATABASE statement for a database containing InnoDB tables, an index could be

corrupted, causing an error message when accessing the table after restart:

InnoDB: Error: trying to load index index_name for table table_name

InnoDB: but the index tree has been freed!

In MySQL 5.1, this fix applies to the InnoDB Plugin, but not the built-in InnoDB storage engine. (Bug

#12861864, Bug #11766019)

• InnoDB: A DDL operation for an InnoDB table could cause a busy MySQL server to halt with an

assertion error:

InnoDB: Failing assertion: trx->error_state == DB_SUCCESS

The error occurred if the DDL operation was run while all 1023 undo slots were in use by concurrent

transactions. This error was less likely to occur in MySQL 5.5 and 5.6, because raising the number of

InnoDB undo slots increased the number of simultaneous transactions (corresponding to the number of

undo slots) from 1K to 128K. (Bug #12739098, Bug #62401)

• InnoDB: InnoDB persistent statistics gave less accurate estimates for date columns than for columns

of other data types. The fix changes the way cardinality is estimated for nonunique keys, and avoids

situations where identical values could be counted twice if they occurred on different index pages. (Bug

#12429443)

• InnoDB: The innodb_max_purge_lag variable controls how to delay DML operations when purge

operations are lagging. Previously, if an old consistent read view was detected, DML operations would

not be delayed even though the purge lag exceeded the innodb_max_purge_lag setting.

Additionally, if the innodb_max_purge_lag setting was used, situations could arise in which the

DML delay time would continue to increase but not be applied right away due to the presence an old

consistent read view. This could result in a lengthy DML delay when the accumulated DML delay time is

eventually applied.

This fix caps the DML delay at a maximum value, removes the consistent read check, and revises the

DML delay calculation. (Bug #12407434, Bug #60776)

• InnoDB: With 1024 concurrent InnoDB transactions running concurrently and the

innodb_file_per_table setting enabled, a CREATE TABLE operation for an InnoDB table could fail.

222

MySQL 5.6 Release Notes

The .ibd file from the failed CREATE TABLE was left behind, preventing the table from being created

later, after the load had dropped.

The fix adds error handling to delete the erroneous .ibd file. This error was less likely to occur in

MySQL 5.5 and 5.6, because raising the number of InnoDB undo slots increased the number of

simultaneous transactions needed to trigger the bug, from 1K to 128K. (Bug #12400341)

• InnoDB: Improved the accuracy of persistent InnoDB statistics for large tables. The estimate of distinct

records could be inaccurate if the index tree was more than 3 levels deep. (Bug #12316365)

• InnoDB: Shutdown could hang with messages like this in the log:

Waiting for purge thread to be suspended

After 1 hour, the shutdown times out and mysqld quits. This problem is most likely to occur with a high

value for innodb_purge_threads. (Bug #11765863, Bug #58868, Bug #60939)

• InnoDB: When DROP TABLE failed due to all undo slots being in use, the error returned was Unknown

table '...' rather than the expected Too many active concurrent transactions. (Bug

#11764724, Bug #57586)

References: See also: Bug #11764668, Bug #57529.

• InnoDB: Server startup could produce an error for temporary tables using the InnoDB storage engine, if

the path in the $TMPDIR variable ended with a / character. The error log would look like:

120202 19:21:26 InnoDB: Operating system error number 2 in a file operation.

InnoDB: The error means the system cannot find the path specified.

InnoDB: If you are installing InnoDB, remember that you must create

InnoDB: directories yourself, InnoDB does not create them.

120202 19:21:26 InnoDB: Error: trying to open a table, but could not

InnoDB: open the tablespace file './t/#sql7750_1_0.ibd'!

InnoDB: Have you moved InnoDB .ibd files around without using the

InnoDB: commands DISCARD TABLESPACE and IMPORT TABLESPACE?

InnoDB: It is also possible that this is a temporary table #sql...,

InnoDB: and MySQL removed the .ibd file for this.

The workaround for the problem was to create a similar temporary table again, copy its .frm file to

tmpdir under the name mentioned in the error message (for example, #sql123.frm) and restart

mysqld with tmpdir set to its normal value without a trailing slash, for example /var/tmp. On

startup, MySQL would see the .frm file and issue DROP TABLE for the orphaned temporary table. (Bug

#11754376, Bug #45976)

• Partitioning: When creating a view from a SELECT statement that used explicit partition selection, the

partition selection portion of the query was ignored. (Bug #13559657)

• Partitioning: Adding a partition to an already existing LIST-partitioned table did not work correctly if

the number of items in the new partition was greater than 16. This could happen when trying to add

a partition using an ALTER TABLE ... ADD PARTITION statement, or an ALTER TABLE ...

REORGANIZE PARTITION statement.

This 16-item limit was not apparent when using either CREATE TABLE ... PARTITION BY LIST or

ALTER TABLE ... PARTITION BY LIST. (Bug #13029508, Bug #62505)

• Partitioning: A function internal to the code for finding matching subpartitions represented an unsigned

number as signed, with the result that matching subpartitions were sometimes missed in results of

queries. (Bug #12725206, Bug #61765)

References: See also: Bug #20257.

223

MySQL 5.6 Release Notes

• Partitioning: An ALTER TABLE ... ADD PARTITION statement subsequent to ALTER TABLE ...

REORGANIZE PARTITION failed on a table partitioned by HASH or KEY. (Bug #11764110, Bug #56909)

• Replication: Executing mysqlbinlog with the --start-position=N option, where N was equal

either to 0 or to a value greater than the length of the dump file, caused it to crash.

This issue was introduced in MySQL 5.5.18 by the fix for Bug #32228 and Bug #11747416. (Bug

#13593869, Bug #64035)

References: This issue is a regression of: Bug #32228, Bug #11747416.

• Replication: When starting the server, replication repositories were checked even when the server_id

system variable was equal to 0 (the default), in spite of the fact that a valid nonzero value for

server_id must be supplied for a server that acts as either a master or a slave in MySQL replication.

This could cause problems when trying to perform a live upgrade from MySQL 5.5, although it was

possible to work around the issue by starting the server with --skip-slave-start (in addition to any

other required options).

To avoid this problem, replication repositories are now checked only when the server is started with --

server-id using a nonzero value. (Bug #13427444, Bug #13504821)

• Replication: Formerly, the default value shown for the Port column in the output of SHOW SLAVE

HOSTS was 3306 whether the port had been set incorrectly or not set at all. Now, when the slave port is

not set, the actual port used by the slave is shown. This change also affects the default shown for the --

report-port server option. (Bug #13333431)

• Replication: A race condition could occur when running multiple instances of mysqld on a single

machine, when more than slave thread was started at the same time, and each such thread tried to use

the same temporary file concurrently. (Bug #12844302, Bug #62055)

• Replication: It was possible on replication slaves where FEDERATED tables were in use to get

timeouts on long-running operations, such as Error 1160 Got an error writing communication

packets. The FEDERATED tables did not need to be replicated for the issue to occur. (Bug #11758931,

Bug #51196)

References: See also: Bug #12896628, Bug #61790.

• Replication: Statements that wrote to tables with AUTO_INCREMENT columns based on an unordered

SELECT from another table could lead to the master and the slave going out of sync, as the order in

which the rows are retrieved from the table may differ between them. Such statements include any

INSERT ... SELECT, REPLACE ... SELECT, or CREATE TABLE ... SELECT statement. Such

statements are now marked as unsafe for statement-based replication, which causes the execution of

one to throw a warning, and forces the statement to be logged using the row-based format if the logging

format is MIXED. (Bug #11758263, Bug #50440)

• Replication: On Windows replication slave hosts, STOP SLAVE took an excessive length of time to

complete when the master was down. (Bug #11752315, Bug #43460)

• Replication: mysqlbinlog --database=dbname included all SET INSERT_ID=n assignments from

the binary log in its output, even if database dbname was never referenced in the binary log. This was

due to the fact that COMMIT statements were not associated with any database in the binary log. Now in

such cases, the current database is tracked so that only those SET INSERT_ID assignments that are

224

MySQL 5.6 Release Notes

made in the context of changes to tables in database dbname are actually printed in the mysqlbinlog

output. (Bug #11746146, Bug #23894)

References: See also: Bug #23890, Bug #46998, Bug #11761686, Bug #54201, Bug #11754117, Bug

#45670.

• Microsoft Windows: On Windows, rebuilds in a source distribution failed to create the initial database

due to insufficient cleanup from the previous run or failure to find the proper server executable. (Bug

#13431251)

• Microsoft Windows: On Windows, the server incorrectly constructed the full path name of the plugin

binary for INSTALL PLUGIN and CREATE FUNCTION ... SONAME. (Bug #45549, Bug #11754014)

• mysqldump tried to execute SET statements as SET OPTION, which failed when used against 5.6 or

higher servers because the deprecated OPTION keyword has been removed from SET syntax. (Bug

#13813473)

• The optimizer did not perform constant propagation for views, so a query containing views resulted in a

less efficient execution plan than the corresponding query using only base tables. (Bug #13783777)

• A memory leak could occur for queries containing a subquery that used GROUP BY on an outer column.

(Bug #13724099)

• After using an ALTER TABLE statement to change the KEY_BLOCK_SIZE property for an InnoDB table,

for example when switching from an uncompressed to a compressed table, subsequent server restarts

could fail with a message like:

InnoDB: Error: data file path/ibdata2 uses page size 1024,

InnoDB: but the only supported page size in this release is=16384

This issue is a regression introduced in MySQL 5.5.20. (Bug #13698765, Bug #64160)

• In debug builds, a Debug Sync timeout warning was treated as an error, causing an assertion to be

raised. (Bug #13688248)

• _mi_print_key() iterated one time too many when there was a NULL bit, resulting in Valgrind

warnings. (Bug #13686970)

• Pushing down to InnoDB an index condition that called a stored function resulted in a server crash. This

kind of condition is no longer pushed down. (Bug #13655397)

• A SELECT from a subquery that returned an empty result could itself fail to return an empty result as

expected. (Bug #13651009, Bug #13650418)

• For debug builds, negative values with a zero integer part and nonzero fractional part (such as -0.1111)

were not detected, so the negative fractional part was later cast to a large unsigned number and raised

an assertion. (Bug #13616434)

• If during server startup a signal such as SIGHUP was caught prior to full server initialization, the server

could crash. This was due to a race condition between the signal handler thread and the main thread

performing server initialization. To prevent this from happening, signal processing is now suspended

until full initialization of all server subsystems has been completed successfully. (Bug #13608371, Bug

#62311)

• The shared version of libmysqlclient did not export these functions for linking by client programs:

get_tty_password(), handle_options(), my_print_help(). (Bug #13604121)

225

MySQL 5.6 Release Notes

• An aggregated expression of type MIN() or MAX() should return NULL but could instead return the

empty set if the query was implicitly grouped and there was no HAVING clause that evaluates to FALSE.

(Bug #13599013)

• Left join queries could be incorrectly converted to inner joins and return erroneous result sets. (Bug

#13595212)

• Date-handling code could raise an assertion attempting to calculate the number of seconds since the

epoch. (Bug #13545236)

• For queries that used a join type of ref_or_null, the optimizer could skip the filesort operation and

sort the results incorrectly. (Bug #13531865)

• For some queries, a filesort operation was done even when the result contained only a single row and

needed no sorting. (Bug #13529048)

• The optimizer could return an incorrect select limit in some cases when a query included no explicit

LIMIT clause. (Bug #13528826)

• In some cases, the optimizer failed to use a covering index when that was possible and read data rows

instead. (Bug #13514959)

• SELECT statements failed for the EXAMPLE storage engine. (Bug #13511529)

References: This issue is a regression of: Bug #11746275.

• The Performance Schema instrumentation for stages did not fully honor the ENABLED column in the

schema.setup_instruments table. (Bug #13509513)

• Converting a string ending with a decimal point (such as '1.') to a floating-point number raised a data

truncation warning. (Bug #13500371)

• Use of an uninitialized TABLE_SHARE member could cause a server crash. (Bug #13489996)

• Some outer joins that used views as inner tables did not evaluate conditions correctly. (Bug #13464334)

• A query that used an index on a CHAR column referenced in a BETWEEN clause could return invalid

results. (Bug #13463488, Bug #63437)

• Expressions that compared a BIGINT column with any non-integer constant were performed using

integers rather than decimal or float values, with the result that the constant could be truncated. This

could lead to any such comparison that used <, >, <=, >=, =, !=/<>, IN, or BETWEEN yielding false

positive or negative results. (Bug #13463415, Bug #11758543, Bug #63502, Bug #50756)

• An application linked against libmysqld could crash in debug mode with a stack smashing

detected error if it tried to connect without specifying the user name. (Bug #13460909)

• Instantiating a derived table for a query with an empty result caused a server crash. (Bug #13457552)

• When the optimizer performed conversion of DECIMAL values while evaluating range conditions, it could

produce incorrect results. (Bug #13453382)

• Implicitly grouped queries with a const table and no matching rows could return incorrect results. (Bug

#13430588)

• For debug builds, enabling optimizer_trace could cause an assertion to be raised. (Bug #13430443)

• Enabling index condition pushdown could cause performance degradation. (Bug #13430436)

226

MySQL 5.6 Release Notes

• When a fixed-width row was inserted into a MyISAM temporary table, the entire content of the record

buffer was written to the table, including any trailing space contained in VARCHAR columns, the issue

being that this trailing space could be uninitialized. This problem has been resolved by insuring that only

the bytes actually used to store the VARCHAR (and none extra) are copied and inserted in such cases.

(Bug #13389854, Bug #79028, Bug #22123583)

• Fractional seconds parts were lost for certain UNION ALL queries. (Bug #13375823)

• When merging ranges that effectively resulted in a full index scan, the optimizer did not discard the

range predicate as unneeded. (Bug #13354910)

• When executing EXPLAIN, it was assumed that only the default multi-range read implementation could

produce an ordered result; this meant that when a query on a table that used a storage engine providing

its own sorted MRR, it was ignored, so that EXPLAIN failed to report Using MRR even when a multi-

range read was used. (Bug #13330645)

• Some multiple-table updates could update a row twice. (Bug #13095459)

• Performance Schema idle event timings were not normalized to the same units as wait timings. (Bug

#13018537)

• In MySQL 5.6.3, a number of status variables were changed to longlong types so that they would

roll over much later. However, the format string used by mysqladmin status to print Queries per

second values did not reflect this, causing such values to be misreported. (Bug #12990746)

References: See also: Bug #42698. This issue is a regression of: Bug #11751727.

• For debug builds, two assertions could be raised erroneously for UPDATE statements. (Bug #12912171)

• When the result of a stored function returning a non-integer type was evaluated for NULL, an incorrect

type warning (Warning 1292 Truncated incorrect INTEGER value) is generated, although such

a test for NULL should work with any type. This could cause stored routines not handling the warning

correctly to fail.

The issue could be worked around by wrapping the result in an expression, using a function such as

CONCAT(). (Bug #12872824, Bug #62125)

• When running mysqldump with both the --single-transaction and --flush-logs options, the

flushing of the log performed an implicit COMMIT (see Statements That Cause an Implicit Commit),

causing more than one transaction to be used and thus breaking consistency. (Bug #12809202, Bug

#61854)

• A query that used an aggregate function such as MAX() or MIN() of an index with NOT BETWEEN in the

WHERE clause could fail to match rows, thus returning an invalid result. (Bug #12773464, Bug #61925)

• With ONLY_FULL_GROUP_BY SQL mode enabled, columns that were not aggregated in the select list or

named in a GROUP BY were incorrectly permitted in ORDER BY. (Bug #12626418)

• Mishandling of NO_BACKSLASH_ESCAPES SQL mode within stored procedures on slave servers could

cause replication failures. (Bug #12601974)

• Passing a user variable as an argument to GROUP_CONCAT() could cause a server exit if the variable

value changed during query execution. (Bug #12408412)

• LOAD INDEX INTO CACHE could cause a server exit if the index cache was too small. (Bug

#12361113)

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MySQL 5.6 Release Notes

• With ONLY_FULL_GROUP_BY SQL mode enabled, a query that uses GROUP BY on a column derived

from a subquery in the FROM clause failed with a column isn't in GROUP BY error, if the query was

in a view. (Bug #11923239)

• Attempting to execute ALTER TABLE on a temporary MERGE table having an underlying temporary table

rendered the MERGE table unusable, unless the ALTER TABLE specified a new list of underlying tables.

(Bug #11764786, Bug #57657)

• It was possible in the event of successive failures for mysqld_safe to restart quickly enough to

consume excessive amounts of CPU. Now, on systems that support the sleep and date system

utilities, mysqld_safe checks to see whether it has restarted more than 5 times in the current second,

and if so, waits 1 second before attempting another restart. (Bug #11761530, Bug #54035)

• A HAVING clause in a query using MIN() or MAX() was sometimes ignored. (Bug #11760517, Bug

#52935)

References: See also: Bug #11758970, Bug #51242, Bug #11759718, Bug #52051.

• When used with the --xml option, mysqldump --routines failed to dump any stored routines,

triggers, or events. (Bug #11760384, Bug #52792)

• If an attempt to initiate a statement failed, the issue could not be reported to the client because it was not

prepared to receive any error messages prior to the execution of any statement. Since the user could not

execute any queries, they were simply disconnected without providing a clear error.

After the fix for this issue, the client is prepared for an error as soon as it attempts to initiate a statement,

so that the error can be reported prior to disconnecting the user. (Bug #11755281, Bug #47032)

• Previously, .OLD files were not included among the files deleted by DROP DATABASE. Files with this

extension are now also deleted by the statement. (Bug #11751736, Bug #42708)

• A prepared statement using a view whose definition changed between preparation and execution

continued to use the old definition, which could cause the prepared statement to return incorrect results.

(Bug #11748352, Bug #36002)

• Some debugging information was written to the buffer after a flush, resulting in the information not

appearing until the next flush. (Bug #64048, Bug #13608112)

• Locale information for FORMAT() function instances was lost in view definitions. (Bug #63020, Bug

#13344643)

• mysqlhotcopy failed for databases containing views. (Bug #62472, Bug #13006947, Bug #12992993)

• The VIO description string was initialized even for connections where it was unneeded. (Bug #62285,

Bug #12951586)

• On Windows, pasting multiple-line input including a CRLF terminator on the last line into the mysql

client resulted in the first character of the last line being changed, resulting in erroneous statements.

Handling of newlines in pasted input was also incorrect. (Bug #60901, Bug #12589167, Bug #64104,

Bug #13639107)

• The contents of the shared and shared-compat RPM packages had been changed in versions

5.5.6 and 5.6.1 to avoid the overlap which they traditionally had (and still have in MySQL 5.0 and 5.1).

However, the RPM meta information had not been changed in accordance, and so RPM still assumed a

conflict between shared and shared-compat RPM packages. This has been fixed. (Bug #60855, Bug

#12368215)

References: See also: Bug #56150.

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MySQL 5.6 Release Notes

• The result of SUBSTRING_INDEX() could be missing characters when used as an argument to

conversion functions such as LOWER(). (Bug #60166, Bug #11829861)

• UPDATE IGNORE returned an incorrect count for number of rows updated when there were duplicate-key

conflicts in a multiple-table update. (Bug #59715, Bug #11766576)

• The optimizer mishandled STRAIGHT_JOIN used with nested joins; for example, by not evaluating

tables in the specified order. (Bug #59487, Bug #11766384, Bug #43368, Bug #11752239, Bug #60080,

Bug #11766858)

• A subquery involved in a comparison requiring a character set conversion caused an error that resulted

in a server crash. (Bug #59185, Bug #11766143)

• The embedded server crashed when argc = 0. (Bug #57931, Bug #12561297)

• If tables were locked by LOCK TABLES ... READ in another session, SET GLOBAL read_only = 1

failed to complete. (Bug #57612, Bug #11764747)

• Invalid memory reads could occur when cmp_item_sort_string::store_value() tried to refer to

a temporary value that could be changed or deleted by other functions. (Bug #57510, Bug #11764651)

• Assigning the result of a subquery to a user variable raised an assertion when the outer query included

DISTINCT and GROUP BY. (Bug #57196, Bug #11764371)

• For comparisons containing out-of-range constants, the optimizer permitted warnings to leak through to

the client, even though it accounted for the range issue internally. (Bug #56962, Bug #11764155)

• A confusing CREATE TABLE error message was improved. (Bug #54963, Bug #11762377)

• The handle_segfault() signal-handler code in mysqld could itself crash due to calling unsafe

functions. (Bug #54082, Bug #11761576)

• Using myisamchk with the sort recover method to repair a table having fixed-width row format could

cause the row pointer size to be reduced, effectively resulting in a smaller maximum data file size. (Bug

#48848, Bug #11756869)

• Enabling myisam_use_mmap could cause the server to crash. (Bug #48726, Bug #11756764)

• For MEMORY tables, a scan of a HASH index on a VARCHAR column could fail to find some rows if the

index was on a prefix of the column. (Bug #47704, Bug #11755870)

• myisam_sort_buffer_size could not be set larger than 4GB on 64-bit systems. (Bug #45702, Bug

#11754145)

• The stored routine cache was subject to a small memory leak that over time or with many routines being

used could result in out-of-memory errors.

The fix for this issue also introduces a new global server system variable stored_program_cache

which can be used for controlling the size of the stored routine cache. (Bug #44585, Bug #11753187)

• Under some circumstances, the result of SUBSTRING_INDEX() incorrectly depended on the contents of

the previous row. (Bug #42404, Bug #11751514)

• Setting an event to DISABLED status and with the ON COMPLETION NOT PRESERVE attribute caused it

to be dropped at the next server restart. (Bug #37666, Bug #11748899)

• Due to improper locking, concurrent inserts into an ARCHIVE table at the same time as repair and check

operations on the table resulted in table corruption. (Bug #37280, Bug #11748748)

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MySQL 5.6 Release Notes

• Stored functions could produce an error message that referred to ORDER BY even though the offending

statement within the function had no such clause. (Bug #35410, Bug #11748187)

Changes in MySQL 5.6.4 (2011-12-20, Milestone 7)

Note

This is a milestone release, for use at your own risk. Upgrades between milestone

releases (or from a milestone release to a GA release) are not supported.

Significant development changes take place in milestone releases and you may

encounter compatibility issues, such as data format changes that require attention

in addition to the usual procedure of running mysql_upgrade. For example, you

may find it necessary to dump your data with mysqldump before the upgrade and

reload it afterward. (Making a backup before the upgrade is a prudent precaution in

any case.)

• Condition Handler Changes

• Fractional Seconds Handling

• InnoDB Notes

• Optimizer Notes

• Performance Schema Notes

• Functionality Added or Changed

• Bugs Fixed

Condition Handler Changes

• Incompatible Change: MySQL now supports the GET DIAGNOSTICS statement. GET DIAGNOSTICS

provides applications a standardized way to obtain information from the diagnostics area, such as

whether the previous SQL statement produced an exception and what it was. See GET DIAGNOSTICS

Statement.

In addition, several deficiencies in condition handler processing rules were corrected so that MySQL

behavior is more like standard SQL:

• Block scope is used in determining which handler to select. Previously, a stored program was treated

as having a single scope for handler selection.

• Condition precedence is more accurately resolved.

• Diagnostics area clearing has changed. Bug #55843 caused handled conditions to be cleared from the

diagnostics area before activating the handler. This made condition information unavailable within the

handler. Now condition information is available within the handler, which can inspect it with the GET

DIAGNOSTICS statement. The condition information is cleared when the handler exits, if it has not

already been cleared during handler execution.

• Previously, handlers were activated as soon as a condition occurred. Now they are not activated until

the statement in which the condition occurred finishes execution, at which point the most appropriate

handler is chosen. This can make a difference for statements that raise multiple conditions, if a

condition raised later during statement execution has higher precedence than an earlier condition and

there are handlers in the same scope for both conditions. Previously, the handler for the first condition

raised would be chosen, even if it had a lower precedence than other handlers. Now the handler for

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MySQL 5.6 Release Notes

the condition with the highest precedence is chosen, even if it is not the first condition raised by the

statement.

• Issues that caused the server to exit due to incorrect handler call stack processing were fixed.

The work just described involved several condition-handler bug fixes:

• The RETURN statement did not clear the diagnostics area as it should have. Now the diagnostics area

is cleared before executing RETURN. This prevents a condition in a nested function call from incorrectly

propagating to an outer scope. It also means there is no way to return an SQL warning from a stored

function. This change is not backward compatible, but the resulting behavior is more like standard

SQL.

• When an SQL HANDLER was activated, the handled condition was immediately removed from the

diagnostics area. Consequently, any SQL diagnostic statement executed in the handler was unable

to examine the condition that activated the handler. Now condition information is available within the

handler.

• If multiple handlers existed at the same level within a stored program, the wrong one could be chosen.

Now the handler for the highest precedence condition is chosen.

• If an error occurred in a context where different handlers were present at different levels of nesting, an

outer handler could be chosen rather than the innermost one.

For more information, see Scope Rules for Handlers. (Bug #12951117, Bug #38806, Bug #11749343,

Bug #55852, Bug #11763171, Bug #61392, Bug #12652873, Bug #11660, Bug #11745196, Bug #48637,

Bug #11756690, WL #2111, WL #5986)

Fractional Seconds Handling

• Incompatible Change: MySQL now permits fractional seconds for TIME, DATETIME, and TIMESTAMP

values, with up to microseconds (6 digits) precision. To define a column that includes a fractional

seconds part, use the syntax type_name(fsp), where type_name is TIME, DATETIME, or

TIMESTAMP, and fsp is the fractional seconds precision. For example:

CREATE TABLE t1 (t TIME(3), dt DATETIME(6));

The fsp value, if given, must be in the range 0 to 6. A value of 0 signifies that there is no fractional part.

If omitted, the default precision is 0. (This differs from the standard SQL default of 6, for compatibility

with previous MySQL versions.)

The following items summarize the implications of this change. See also Fractional Seconds in Time

Values.

• For TIME, DATETIME, and TIMESTAMP columns, the encoding and storage requirements in new

tables differ from such columns in tables created previously because these types now include a

fractional seconds part. This can affect the output of statements that depend on the row format, such

as CHECKSUM TABLE.

• Due to these changes in encoding and storage requirements for MySQL's DATETIME and TIMESTAMP

types, importing pre-MySQL 5.6.4 InnoDB tables using ALTER TABLE ... IMPORT TABLESPACE

that contain DATETIME and TIMESTAMP types into MySQL 5.6.4 (or later) requires a workaround

procedure which is described in the “Server Changes” section of Changes in MySQL 5.6 .

• Syntax for temporal literals now produces temporal values: DATE 'str', TIME 'str', and

TIMESTAMP 'str', and the ODBC-syntax equivalents. The resulting value includes a trailing

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MySQL 5.6 Release Notes

fractional seconds part if specified. Previously, the temporal type keyword was ignored and these

constructs produced the string value. See Standard SQL and ODBC Date and Time Literals

• Functions that take temporal arguments accept values with fractional seconds. Return values from

temporal functions include fractional seconds as appropriate.

• Three INFORMATION_SCHEMA tables, COLUMNS, PARAMETERS, and ROUTINES, now have a

DATETIME_PRECISION column. Its value is the fractional seconds precision for TIME, DATETIME,

and TIMESTAMP columns, and NULL for other data types.

• The C API accommodates fractional seconds as follows:

• In the MYSQL_FIELD column metadata structure, the decimals member indicates the fractional

seconds precision for TIME, DATETIME, and TIMESTAMP columns. Clients can determine whether

a result set temporal column has a fractional seconds part by checking for a nonzero decimals

value in the corresponding MYSQL_FIELD structure. Previously, the decimals member indicated

the precision for numeric columns and was zero otherwise.

• In the MYSQL_TIME structure used for the binary protocol, the second_part member indicates the

microseconds part for TIME, DATETIME, and TIMESTAMP columns. Previously, the second_part

member was unused.

In some cases, previously accepted syntax may produce different results. The following items indicate

where existing code may need to be changed to avoid problems:

• Some expressions produce results that differ from previous results. Examples: The timestamp

system variable returns a value that includes a microseconds fractional part rather than an integer

value. Functions that return a result that includes the current time (such as CURTIME(), SYSDATE(),

or UTC_TIMESTAMP()) interpret an argument as an fsp value and the return value includes a

fractional seconds part of that many digits. Previously, these functions permitted an argument but

ignored it.

• TIME values are converted to DATETIME by adding the time to the current date. (This means that

the date part of the result differs from the current date if the time value is outside the range from

'00:00:00' to '23:59:59'.) Previously, conversion of TIME values to DATETIME was unreliable.

See Conversion Between Date and Time Types.

• TIMESTAMP(N) was permitted in old MySQL versions, but N was a display width rather than fractional

seconds precision. Support for this behavior was removed in MySQL 5.5.3, so applications that are

reasonably up to date should not be subject to this issue. Otherwise, code must be rewritten.

Note

There may be problems replicating from a master server that understands

fractional seconds to an older slave that does not:

• For CREATE TABLE statements containing columns that have an fsp value

greater than 0, replication will fail due to parser errors.

• Statements that use temporal data types with an fsp value of 0 will work for

with statement-based logging but not row-based logging. In the latter case, the

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MySQL 5.6 Release Notes

data types have binary formats and type codes on the master that differ from

those on the slave.

• Some expression results will differ on master and slave. For example,

expressions that involve the timestamp system variable or functions that

return the current time have different results, as described earlier.

(Bug #8523, Bug #11745064, WL #946)

InnoDB Notes

• MySQL now supports FULLTEXT indexes for InnoDB tables. The core syntax is very similar to

the FULLTEXT capability from earlier releases, with the CREATE TABLE and CREATE INDEX

statements, and MATCH() AGAINST() clause in the SELECT statement. The new @ operator

allows proximity searches for terms that are near each other in the document. The detailed search

processing is controlled by a new set of configuration options: innodb_ft_enable_stopword,

innodb_ft_server_stopword_table, innodb_ft_user_stopword_table,

innodb_ft_cache_size, innodb_ft_min_token_size, and innodb_ft_max_token_size.

You can monitor the workings of the InnoDB full-text search system by querying new

INFORMATION_SCHEMA tables: innodb_ft_default_stopword, innodb_ft_index_table,

innodb_ft_index_cache, innodb_ft_config, innodb_ft_deleted, and

innodb_ft_being_deleted. (WL #5538)

Optimizer Notes

• These query optimizer improvements were implemented:

• The optimizer detects and optimizes away these useless query parts within IN/ALL/SOME/EXISTS

subqueries:

• DISTINCT

• GROUP BY, if there is no HAVING clause and no aggregate functions

• ORDER BY, which has no effect because LIMIT is not supported in these subqueries

(WL #5953)

Performance Schema Notes

• The Performance Schema has these additions:

• The Performance Schema now permits instrument and consumer configuration at server

startup, which previously was possible only at runtime using UPDATE statements for the

setup_instruments and setup_consumers tables. This change was made because configuration

at runtime is too late to disable instruments that have already been initialized during server startup. For

example, the wait/sync/mutex/sql/LOCK_open mutex is initialized once during server startup, so

attempts to disable the corresponding instrument at runtime have no effect.

To control an instrument at server startup, use an option of this form:

--performance-schema-instrument='instrument_name=value'

Here, instrument_name is an instrument name such as wait/sync/mutex/sql/LOCK_open,

and value is one of these values:

• off, false, or 0: Disable the instrument

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MySQL 5.6 Release Notes

• on, true, or 1: Enable and time the instrument

• counted: Enable and count (rather than time) the instrument

Each --performance-schema-instrument option can specify only one instrument name, but

multiple instances of the option can be given to configure multiple instruments. In addition, patterns

are permitted in instrument names to configure instruments that match the pattern. To configure all

condition synchronization instruments as enabled and counted, use this option:

--performance-schema-instrument='wait/synch/cond/%=counted'

To disable all instruments, use this option:

--performance-schema-instrument='%=off'

Longer instrument name strings take precedence over shorter pattern names, regardless of order. For

information about specifying patterns to select instruments, see Naming Instruments or Consumers for

Filtering Operations.

An unrecognized instrument name is ignored. It is possible that a plugin installed later may create the

instrument, at which time the name is recognized and configured.

To control a consumer at server startup, use an option of this form:

--performance-schema-consumer_consumer_name=value

Here, consumer_name is a consumer name such as events_waits_history, and value is one of

these values:

• off, false, or 0: Do not collect events for the consumer

• on, true, or 1: Collect events for the consumer

For example, to enable the events_waits_history consumer, use this option:

--performance-schema-consumer-events-waits-history=on

The permitted consumer names can be found by examining the setup_consumers table. Patterns

are not permitted.

Along with the preceding changes to permit configuration at server startup, the default instrument and

consumer configuration has changed. Previously, all instruments and consumers were enabled by

default. Now, instruments are disabled except the statement, I/O, and idle instruments. Consumers

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MySQL 5.6 Release Notes

are disabled except the global, thread, and current-statement consumers. These changes produce a

default configuration with a low overhead.

• Tables that have an EVENT_ID column now also have an END_EVENT_ID column to support

determination of nested event relationships:

• events_waits_current, events_waits_history, events_waits_history_long

• events_stages_current, events_stages_history, events_stages_history_long

• events_statements_current, events_statements_history,

events_statements_history_long

As before, EVENT_ID is populated with the thread current event counter when an event starts. In

addition, END_EVENT_ID is NULL until the event ends, at which point it is set to the new thread current

event counter. This permits the relationship “event B is included in event A” to be determined using the

following expression, without having to follow each inclusion relationship using NESTING_EVENT_ID:

A.EVENT_ID <= B.EVENT_ID AND B.END_EVENT_ID <= A.END_EVENT_ID

• The Performance Schema aggregates file I/O operations in two places, the

events_waits_summary_xxx tables and the file_summary_xxx tables. It was

possible to join the events_waits_summary_global_by_event_name table to the

file_summary_by_event_name by using the EVENT_NAME column. However, it was not possible to

do the same with the events_waits_summary_by_instance and file_summary_by_instance

tables because the former uses OBJECT_INSTANCE_BEGIN as the instance identifier and the latter

uses FILE_NAME. This means that it was possible to obtain both file I/O latency and usage per file, but

not to correctly correlate latency to usage when there was more than one form of file (such as multiple

redo logs, table files, and so forth).

To address this issue, the file_summary_by_instance table now has an

OBJECT_INSTANCE_BEGIN column. In addition, both file_summary_by_instance and

file_summary_by_event_name have additional aggregation columns (such as timer wait

information), which in many cases makes it possible to obtain the desired summary information

without need for a join at all.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the performance_schema database.

For more information, see MySQL Performance Schema. (WL #5863, WL #5908, WL #5461)

Functionality Added or Changed

• Performance; InnoDB: New optimizations apply to read-only InnoDB transactions. See Optimizing

InnoDB Read-Only Transactions for details. The new optimizations make autocommit more applicable

to InnoDB queries than before, as a way to signal that a transaction is read-only because it is a single-

statement SELECT. (WL #6046)

• Performance; InnoDB: You can now set the InnoDB page size for uncompressed tables to 8KB

or 4KB, as an alternative to the default 16KB. This setting is controlled by the innodb_page_size

configuration option. You specify the size when creating the MySQL instance. All InnoDB tablespaces

within an instance share the same page size. Smaller page sizes can help to avoid redundant or

inefficient I/O for certain combinations of workload and storage devices, particularly SSD devices with

small block sizes. (WL #5756)

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MySQL 5.6 Release Notes

• Replication: Previously, replication slaves could connect to the master server only through master

accounts that use native authentication. Now replication slaves can also connect through master

accounts that use nonnative authentication if the required client-side plugin is installed on the slave side

in the directory named by the slave plugin_dir system variable. (Bug #12897501)

• The optimizer trace capability now tracks temporary tables created by the server during statement

execution. (Bug #13400713)

• Performance of metadata locking operations on Windows XP systems was improved by instituting a

cache for metadata lock objects. This permits the server to avoid expensive operations for creation and

destruction of synchronization objects on XP. A new system variable, metadata_locks_cache_size,

permits control over the size of the cache. The default size is 1024. (Bug #12695572)

• Upgrading from an Advanced GPL RPM package to an Advanced RPM package did not work. Now

on Linux it is possible to use rpm -U to replace any installed MySQL product by any other of the same

release family. It is not necessary to remove the old produce with rpm -e first. (Bug #11886309)

• The make_win_bin_dist script is no longer used and has been removed from MySQL distributions

and the manual. (Bug #58241)

• MEMORY table creation time is now available in the CREATE_TIME column of the

INFORMATION_SCHEMA.TABLES table and the Create_time column of SHOW TABLE STATUS output.

(Bug #51655, Bug #11759349)

• Previously, MySQL servers from 5.1 and up refused to open ARCHIVE tables created in 5.0 because

opening them caused a server crash. The server now can open 5.0 ARCHIVE tables, and REPAIR

TABLE updates them to the format used in 5.6. However, the recommended upgrade procedure is still

to dump 5.0 ARCHIVE tables before upgrading and reload them after upgrading. (Bug #48633, Bug

#11756687)

• Error messages that referred only to an error code now also include the corresponding error description.

(Bug #48348, Bug #11756433)

• The MySQL code base was changed to permit use of the C++ Standard Library and to enable

exceptions and runtime type information (RTTI). This change has the following implications:

• Libraries and executables depend on some C++ standard library. On Linux, this has not been the case

previously. On Solaris, the default dependency has changed from the default library to libstlport,

which is now included with binary distributions for users whose system does not have it.

• The -fno-rtti and -fno-exceptions options are no longer used to build plugins, such as storage

engines. Users who write their own plugins should omit these options if they were using tem.

• C++ users who compile from source should set CXX to a C++ compiler rather than a C compiler. For

example, use g++ rather than gcc. This includes the server as well as client programs.

• mysql_config now has a --cxxflags option. This is like the --cflags option, but produces flags

appropriate for a C++ compiler rather than a C compiler.

• Loadable functions can be written in C++ using standard library features.

(WL #5825)

Bugs Fixed

• Security Enhancement; Replication: The START SLAVE statement now accepts USER and PASSWORD

options. By default, MySQL native authentication is used, and the user name and password are stored

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MySQL 5.6 Release Notes

in the master.info repository. This behavior can be overridden by additionally specifying the name

(DEFAULT_AUTH) and location (PLUGIN_DIR) of an authentication plugin when issuing START SLAVE. .

As part of this change, warnings are now issued in the following cases:

1. If START SLAVE USER="..." PASSWORD="..." or CHANGE MASTER TO

MASTER_USER="..." MASTER_PASSWORD="..." is executed using an unencrypted connection,

the warning message Sending passwords in plain text without SSL/TLS is

extremely insecure is generated (ER_INSECURE_PLAIN_TEXT).

2. If the user name and password are stored in or read from the master.info repository in the course

of executing CHANGE MASTER TO, a warning message is printed out to the error log: Storing

MySQL user name or password information in the master.info repository is

not secure and is therefore not recommended (ER_INSECURE_CHANGE_MASTER).

Note

The text of a running START SLAVE statement, including values for USER and

PASSWORD, can be seen in the output of a concurrent SHOW PROCESSLIST

statement. The complete text of a CHANGE MASTER TO statement is also visible

to SHOW PROCESSLIST.

See also Pluggable Authentication. (Bug #13083642, WL #4143)

• Incompatible Change; Replication: The statements in the following list are now marked as unsafe for

statement-based replication. This is due to the fact that each of these statements depends on the results

of a SELECT statement whose order cannot always be determined. When using STATEMENT logging

mode, a warning is issued in the binary log for any of these statements; when using MIXED logging

mode, the statement is logged using the row-based format.

• INSERT ... SELECT ... ON DUPLICATE KEY UPDATE

• REPLACE ... SELECT

• CREATE TABLE ... IGNORE SELECT

• CREATE TABLE ... REPLACE SELECT

• INSERT IGNORE ... SELECT

• UPDATE IGNORE

When upgrading, you should note the use of these statements in your applications, keeping in mind that

a statement that inserts or replaces rows obtained from a SELECT can take up many times as much

space in the binary log when logged using row-based format than when only the statement itself is

logged. Depending on the number and size of the rows selected and inserted (or replaced) by any such

statements, the difference in size of the binary log after the logging of these statements is switched from

statement-based to row-based can potentially be several orders of magnitude. See Advantages and

Disadvantages of Statement-Based and Row-Based Replication. (Bug #11758262, Bug #50439)

• Incompatible Change: Previously, “Aborted connection” errors were written to the error log based on

the session value of log_warnings, which permitted users with minimal privileges to cause many

messages to be written to the log unless restricted by the MAX_CONNECTIONS_PER_HOUR resource

limit. Now this logging is based on the global log_warnings variable. There are no remaining uses of

the session log_warnings variable, so it has been removed and the variable now has only a global

value. (Bug #53466, Bug #11761014)

237

MySQL 5.6 Release Notes

• Important Change; InnoDB: If an ALTER TABLE statement failed for an InnoDB table due to an error

code from an underlying file-renaming system call, InnoDB could lose track of the .ibd file for the table.

This issue only occurred when the innodb_file_per_table configuration option was enabled, and

when the low-level error persisted through thousands of retry attempts. In MySQL 5.1, this issue applied

to the InnoDB Plugin but not the built-in InnoDB storage engine.

For example, if you encounter an error like the following:

mysql> ALTER TABLE sb2 ADD COLUMN d2 INT;

ERROR 1025 (HY000): Error on rename of './sbtest/#sql-1eb9_1' to

'./sbtest/sb2' (errno: -1)

you might be able to access the #sql* table by copying an .frm file from a table with an identical

schema. The table name to use for the .frm filewould be `sbtest.#mysql50##sql-1eb9_1` in the

preceding example. (Bug #12884631, Bug #62146)

• Important Change; Replication: Setting an empty user in a CHANGE MASTER TO statement caused

an invalid internal result and is no longer permitted. Trying to use MASTER_USER='' or setting

MASTER_PASSWORD while leaving MASTER_USER unset causes the statement to fail with an error. (Bug

#13427949)

• Performance; InnoDB: The process of deallocating the InnoDB Adaptive Hash Index was made faster,

during shutdown or when turning off the AHI with the statement:

SET GLOBAL innodb_adaptive_hash_index=OFF;

(Bug #13006367, Bug #62487)

• Performance; InnoDB: This fix improves the performance of instrumentation code for InnoDB buffer

pool operations. (Bug #12950803, Bug #62294)

• Performance; InnoDB: This fix improved the efficiency and concurrency of freeing pages in the InnoDB

buffer pool when performing a DROP TABLE for an InnoDB table when the innodb_file_per_table

option is enabled.

This change is most noticeable for systems with large buffer pools. During the drop operation, one

traversal of the buffer pool memory structure is changed from the LRU list (the entire buffer pool) to the

flush list (a much smaller structure). The LRU scanning is reduced, but not entirely eliminated. The buffer

pool mutex is also released periodically, so that if the drop operation takes significant time, other threads

can proceed concurrently. (Bug #11759044, Bug #51325)

• InnoDB: An internal deadlock could occur within InnoDB, on a server doing a substantial amount of

change buffering for DML operations, particularly DELETE statements. (Bug #13340047)

• InnoDB: Fixed a compilation problem that affected the InnoDB source code with gcc 4.6.1. The

affected InnoDB source file was btr/btr0cur.c. (Bug #13116045)

• InnoDB: Querying the INFORMATION_SCHEMA.INNODB_SYS_TABLESTATS table could cause the

server to halt with an assertion error, in debug builds only. (Bug #12960058)

• InnoDB: Valgrind errors when building with the settings innodb_checksum_algorithm=innodb and

innodb_checksum_algorithm=crc32 were fixed. (Bug #12939557)

• InnoDB: Unused functions were removed from the internal InnoDB code related to mini-transactions, to

clarify the logic. (Bug #12626794, Bug #61240)

• InnoDB: Lookups using secondary indexes could give incorrect matches under a specific set of

conditions. The conditions involve an index defined on a column prefix, for a BLOB or other long column

238

MySQL 5.6 Release Notes

stored outside the index page, with a table using the Barracuda file format. (Bug #12601439, Bug

#12543666)

• InnoDB: An UPDATE statement for an InnoDB table could hang. The issue affects tables using the

Barracuda file format and having multiple indexes on column prefixes. The size of an undo log record

could exceed the page size, even though the total size of the column prefixes was less than the

page size (usually 16KB). In MySQL 5.5 and higher, this error is now reported using the new code

ER_UNDO_RECORD_TOO_BIG. In MySQL 5.1 with the InnoDB Plugin, this error is reported using the

existing code ER_TOO_BIG_ROWSIZE. (Bug #12547647)

• InnoDB: This fix corrects cases where the MySQL server could hang or abort with a long semaphore

wait message. (This is a different issue than when these symptoms occurred during a CHECK TABLE

statement.) (Bug #11766591, Bug #59733)

• InnoDB: Issuing INSERT...ON DUPLICATE KEY statements for InnoDB tables from concurrent

threads could cause a deadlock, particularly with the INSERT...ON DUPLICATE KEY UPDATE form.

The problem could also be triggered by issuing multiple INSERT IGNORE statements. The fix avoids

deadlocks caused by the same row being accessed by more than one transaction. Deadlocks could

still occur when multiple rows are inserted and updated simultaneously by different transactions in

inconsistent order; those types of deadlocks require the standard error handling on the application side,

of re-trying the transaction. (Bug #11759688, Bug #52020, Bug #12842206)

• Partitioning: CHECKSUM TABLE returned 0 for a partitioned table unless the statement was used with

the EXTENDED option. (Bug #11933226, Bug #60681)

• Partitioning: Error 1214 (ER_TABLE_CANT_HANDLE_FT), given when trying to use a FULLTEXT

index with a partitioned table, displayed the misleading text The used table type doesn't

support FULLTEXT indexes was misleading and has been replaced with Error 1752

(ER_FULLTEXT_NOT_SUPPORTED_WITH_PARTITIONING) which shows the more accurate FULLTEXT

index is not supported for partitioned tables. (Bug #11763825, Bug #56590)

• Partitioning: Using ALTER TABLE to remove partitioning from a valid MyISAM table could corrupt it.

(Bug #52599, Bug #11760213)

• Replication: The value set for the slave_parallel_workers system variable was not always

honored correctly; in such cases a random value was used. (Bug #13334470)

• Replication: Execution of LOAD DATA on a MyISAM table having an after-insert trigger which wrote into

an InnoDB table caused multithreaded statement-based replication to abort with error 1742 (Cannot

execute the current event group in the parallel mode). (Bug #12982188)

• Replication: Several warnings and informational messages were revised for typographic errors and

clarity. (Bug #12947248, Bug #12978113)

• Replication: When a statement containing a large number of rows to be applied on a slave table that

does not contain a primary key, a considerable amount of time can be needed to find and change all the

rows that are to be changed. The current fix helps diagnose this issue by printing a message to the error

log if the execution time for a given statement replicated using row-based replication takes more than 60

seconds. log_warnings must be greater than 1 for this message to be printed to the error log. (Bug

#11760927, Bug #53375)

• Replication: mysqlbinlog --hexdump printed the last row of the hex dump incorrectly, in two ways:

1. If the length of the last row was eight bytes, the end of the previous row was copied to the end of the

last row, padding the last row to full length.

2. If the length of the last row was less than sixteen bytes, its textual representation was not aligned

with that of previous rows.

239

MySQL 5.6 Release Notes

(Bug #11747887, Bug #34386)

• Replication: A replication master could send damaged events to slaves after the binary log disk on the

master became full. To correct this issue, only complete events are now pushed by the master dump

thread to the slave I/O thread. In addition, the error text that the master sends to the slave when an

incomplete event is found now states that the incomplete event may have been caused by running out

of disk space on the master, and provides coordinates of the first and the last event bytes read. (Bug

#11747416, Bug #32228)

References: See also: Bug #64035, Bug #13593869.

• Replication: --replicate-rewrite-db=from_name->to_name did not work correctly when the

name of the source database (from_name) consisted of only a single character. (Bug #34332, Bug

#11747866)

• An incorrect InnoDB assertion could cause the server to halt. This issue only affected debug builds.

The assertion referenced the source file btr0pcur.ic and the variable cursor->pos_state. (Bug

#13358468)

• A derived table with more than 64 columns caused a server crash. (Bug #13354889)

• With InnoDB change buffering enabled and innodb_page_size set to an 8K or 4K page size, an

UPDATE statement could fail if a column being updated contained a value longer than 1/8th of the page

size. (Bug #13336585)

• Writes to the slow log involved a call to thd->current_utime() even if no log entries ended up being

written, unnecessarily reducing performance. (Bug #13326965)

• Rounding DBL_MAX returned DBL_MAX, not 'inf'. (Bug #13261955)

• For materialized temporary tables, a missing key length check could cause incorrect query results. (Bug

#13261277)

• Access privileges were checked for each stored program instruction, even if the instruction used no

tables, resulting in reduced performance. (Bug #13251277)

• The error message for ER_EVENT_CANNOT_ALTER_IN_THE_PAST was incorrect. (Bug #13247871)

• During the table-opening process, memory was allocated and later freed that was needed view loading,

even for statements that did not use views. These unnecessary allocation and free operations are no

longer done. (Bug #13116518)

• Subqueries with OUTER JOIN could return incorrect results if the subquery referred to a column from

another SELECT. (Bug #13068506)

• Writes to MyISAM temporary tables could include uninitialized data, which could contain sensitive

information. Now only bytes containing initialized data are copied, which also improves performance.

(Bug #12997905)

• The Performance Schema nested some network I/O events within the wrong statement. (Bug

#12981100)

• mysql_plugin mishandled the --plugin-ini, --mysqld, and --my-print-defaults options

under some circumstances. (Bug #12968815)

• mysql_plugin returned the wrong error code from failed server bootstrap execution. (Bug #12968567)

240

MySQL 5.6 Release Notes

• Internal conversion of zero to binary and back could yield a result with incorrect precision. (Bug

#12911710)

• Valgrind warnings generated by filesort operations were fixed. (Bug #12856915)

• An IN-to-EXISTS subquery transformation could yield incorrect results if the outer value list contained

NULL. (Bug #12838171)

• With index condition pushdown enabled, STRAIGHT_JOIN queries could produce incorrect results. (Bug

#12822678, Bug #12724899)

• The result of ROUND() was incorrect for certain numbers. (Bug #12744991)

• A warning resulting from use of SPACE() referred to REPEAT() in the warning message. (Bug

#12735829)

• IN and EXISTS subqueries with DISTINCT and ORDER BY could return incorrect results. (Bug

#12709738)

• A memory leak occurred due to failure to clean up after QUICK_INDEX_MERGE_SELECT/Unique. (Bug

#12694872, Bug #14542543)

• Several improvements were made to the libedit library bundled with MySQL distributions, and that is

available for all platforms that MySQL supports except Windows.

• Navigation keys did not work for UTF-8 input.

• Word navigation and delete operations did not work for UTF-8 input with Cyrillic characters.

• Nonlatin characters were corrupted in overwrite mode for UTF-8 input.

• Long queries caused the statement history file to become corrupted.

• The Alt key caused history operations to fail.

(Bug #12605400, Bug #12613725, Bug #12618092, Bug #12624155, Bug #12617651, Bug #12605388)

• SELECT SQL_BUFFER_RESULT query results included too many rows if a GROUP BY clause was

optimized away. (Bug #12578908)

• decimal_round() could cause a server exit when processing long numeric strings. (Bug #12563865)

• mysqldump --all-databases did not dump the replication log tables. (They could be dumped only by

naming them explicitly when invoking mysqldump, and using the --master-data option.)

As a result of the fix for this problem, it is now possible to execute statements requiring read locks on

the replication log tables at any time, while any statements requiring a write lock on either or both of

these tables are disallowed whenever replication is in progress. For more information, see Relay Log

and Replication Metadata Repositories. (Bug #12402875, Bug #60902)

• The client-server protocol now has the client send authentication data as length-

encoded strings so that data longer than 256 bytes can be sent. This is done using the

CLIENT_PLUGIN_AUTH_LENENC_CLIENT_DATA client capability. (Bug #11878962)

• mysqld_safe did not properly check for an already running instance of mysqld. (Bug #11878394)

• SUM(DISTINCT) incorrectly converted DATE, DATETIME, TIME, and TIMESTAMP arguments to YEAR.

(Bug #73543, Bug #19427648)

241

MySQL 5.6 Release Notes

• If index condition pushdown access was chosen and then abandoned, some variables were not cleared,

leading to incorrect query results. (Bug #62533)

• The CMake configuration checks did not properly test whether the C compiler supports the inline

keyword. (Bug #61708, Bug #12711108)

• For a lower_case_table_names value of 1 or 2 and a database having a mixed-case name, calling

a stored function using a fully qualified name including the database name failed. (Bug #60347, Bug

#11840395)

• mysql_upgrade did not upgrade the system tables or create the mysql_upgrade_info file when run

with the --write-binlog or --skip-write-binlog option. (Bug #60223, Bug #11827359)

• A multiple-table UPDATE statement required the UPDATE privilege on a view which was only read if the

view was processed using the merge algorithm. (Bug #59957, Bug #11766767)

• When a join operation contained a view, the optimizer sometimes failed to associate the view's WHERE

clause with the first table or view in a join when it was possible to do so, resulting in a less efficient

query. (Bug #59696, Bug #11766559)

• An assertion was raised when selecting from a view that selects from a view that used a loadable

function that had been deleted. (Bug #59546, Bug #11766440)

• The help message for mysql_install_db did not indicate that it supports the --defaults-file, --

defaults-extra-file and --no-defaults options. (Bug #58898, Bug #11765888)

• mysql_install_db printed the --skip-grant-tables server option as --skip-grant in one of

its error messages. (Bug #58534, Bug #11765553)

• An assertion designed to detect zero-length sort keys also was raised when the entire key set fit in

memory. (Bug #58200, Bug #11765254)

• During optimization, ZEROFILL values may be converted to string constants. However, CASE

expressions did not handle switching data types after the planning stage, leading to CASE finding a null

pointer instead of its argument. (Bug #57135, Bug #11764313)

• If a plugin was uninstalled, thread local variables for plugin variables of string type with wth

PLUGIN_VAR_MEMALLOC flag were not freed. (Bug #56652, Bug #11763882)

• Deadlock could occur when these four things happened at the same time: 1) An old dump thread was

waiting for the binary log to grow. 2) The slave server that replicates from the old dump thread tried

to reconnect. During reconnection, the new dump thread tried to kill the old dump thread. 3) A KILL

statement tried to kill the old dump thread. 4) An INSERT statement caused a binary log rotation. (Bug

#56299, Bug #11763573)

• myisampack could create corrupt FULLTEXT indexes when compressing tables. (Bug #53646, Bug

#11761180)

• The SQL_BIG_RESULT modifier could change the results for queries that included a GROUP BY clause.

(Bug #53534, Bug #11761078)

• ARCHIVE tables with NULL columns could cause server crashes or become corrupt under concurrent

load. (Bug #51252, Bug #11758979)

• InnoDB used incorrect identifier quoting style in an error message that resulted in an error if a user

followed the suggestion in the message. (Bug #49556, Bug #11757503)

• OPTIMIZE TABLE could corrupt MyISAM tables if myisam_use_mmap was enabled. (Bug #49030, Bug

#11757032)

242

MySQL 5.6 Release Notes

• Concurrent access to ARCHIVE tables could cause corruption. (Bug #42784, Bug #11751793)

• A query that selected a GROUP_CONCAT() function result could return different values depending on

whether an ORDER BY of the function result was present. (Bug #41090, Bug #11750518)

• A linking problem prevented the FEDERATED storage engine plugin from loading. (Bug #40942, Bug

#11750417)

• Subqueries could return incorrect results when materialization was enabled. (Bug #40037, Bug

#11749901, Bug #12705660, Bug #12908058)

• For debug builds, an assertion could be raised for ALTER statements that performed a RENAME

operation. This occurred for storage engine handlertons that exposed the HTON_FLUSH_AFTER_RENAME

flag. (Bug #38028, Bug #11749050)

• The estimate of space required for filesort operations could be too high, resulting in inefficient

initialization. (Bug #37359, Bug #11748783)

• An ALTER TABLE that included an ADD ... AFTER operation to add a new column after a column

that had been modified earlier in the statement failed to find the existing column. (Bug #34972, Bug

#11748057)

• For FEDERATED tables, loss of connection to the remote table during some insert operations could cause

a server crash. (Bug #34660, Bug #11747970)

• For some queries, the index_merge access method was used even when more expensive then ref

access. (Bug #32254, Bug #11747423)

• Collation for the SPACE() function was determined by the parse time value of the

collation_connection system variable (instead of the runtime value), which could give unexpected

results from prepared statements, triggers, and stored procedures. (Bug #23637, Bug #11746123)

Changes in MySQL 5.6.3 (2011-10-03, Milestone 6)

Note

This is a milestone release, for use at your own risk. Upgrades between milestone

releases (or from a milestone release to a GA release) are not supported.

Significant development changes take place in milestone releases and you may

encounter compatibility issues, such as data format changes that require attention

in addition to the usual procedure of running mysql_upgrade. For example, you

may find it necessary to dump your data with mysqldump before the upgrade and

reload it afterward. (Making a backup before the upgrade is a prudent precaution in

any case.)

• Parallel Event Execution (Multithreaded Slave)

• Optimizer Notes

• Performance Schema Notes

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

243

MySQL 5.6 Release Notes

Parallel Event Execution (Multithreaded Slave)

• Replication: MySQL replication now supports a multithreaded slave executing replication events

from the master across different databases in parallel, which can result in significant improvements in

application throughput when certain conditions are met. The optimum case is that the data be partitioned

per database, and that updates within a given database occur in the same order relative to one another

as they do on the master. However, transactions do not need to be coordinated between different

databases.

The slave_parallel_workers server system variable (added in this release) sets the number of

slave worker threads for executing replication events in parallel. When parallel execution is enabled,

the slave SQL thread acts as the coordinator for the slave worker threads, among which transactions

are distributed on a per-database basis. This means that a worker thread on the slave can process

successive transactions on a given database without waiting for updates on other databases to

complete.

Due to the fact that transactions on different databases can occur in a different order on the slave

than on the master, checking for the most recently executed transaction does not guarantee that all

previous transactions from the master have been executed on the slave. This has implications for

logging and recovery when using a multithreaded slave. For information about how to interpret binary

logging information when using multithreading on the slave, see SHOW SLAVE STATUS Statement.

(WL #5569)

Optimizer Notes

• These query optimizer improvements were implemented:

• The EXPLAIN statement now provides execution plan information for DELETE, INSERT, REPLACE,

and UPDATE statements. Previously, EXPLAIN provided information only for SELECT statements.

• The optimizer more efficiently handles subqueries in the FROM clause (that is, derived tables):

• Materialization of subqueries in the FROM clause is postponed until their contents are needed

during query execution, which improves performance. Delay of materialization may even enable the

optimizer to avoid it entirely. Consider a query that joins the result of a subquery in the FROM clause

to another table: If the optimizer processes that other table first and finds that it returns no rows, the

join need not be carried out further and the optimizer need not materialize the subquery at all.

Previously, subqueries in the FROM clause were materialized for EXPLAIN SELECT statements.

This resulted in partial SELECT execution, even though the purpose of EXPLAIN is to obtain query

plan information, not to execute the query. This materialization no longer occurs, so EXPLAIN is

faster for such queries.

• During query execution, the optimizer may add an index to a derived table to speed up row retrieval

from it.

For more information, see Optimizing Derived Tables.

• A Batched Key Access (BKA) join algorithm is now available that uses both index access to the joined

table and a join buffer. The BKA algorithm supports inner join and outer join operations, including

nested outer joins. Benefits of BKA include improved join performance due to more efficient table

scanning.

Two flags have been added to the optimizer_switch system variable (block_nested_loop

and batched_key_access). These flags control how the optimizer uses the Block Nested-Loop

244

MySQL 5.6 Release Notes

and Batched Key Access join algorithms. Previously, the optimizer_join_cache_level system

variable was used for join buffer control; this variable has been removed.

For more information, see Block Nested-Loop and Batched Key Access Joins.

• The optimizer now has a tracing capability. This will be of use to optimizer developers, and also to

users who file bugs against the optimizer and want to provide more information that will help resolve

the bug. The interface is provided by a set of optimizer_trace_xxx system variables and the

INFORMATION_SCHEMA.OPTIMIZER_TRACE table, but is subject to change. For details, see MySQL

Internals: Tracing the Optimizer.

(Bug #44802, Bug #11753371, Bug #14295, Bug #11745379, Bug #27975, Bug #11746677, WL #4897,

WL #5274, WL #5285)

Performance Schema Notes

• The Performance Schema has these additions:

• The Performance Schema now instruments stages and statements. Stages are steps during

the statement-execution process, such as parsing a statement, opening a table, or performing a

filesort operation. Stages correspond to the thread states displayed by SHOW PROCESSLIST or

that are visible in the INFORMATION_SCHEMA.PROCESSLIST table. Stages begin and end when state

values change.

Within the event hierarchy, wait events nest within stage events, which nest within statement

events. To reflect this nesting in wait-event tables such as events_waits_current, the

NESTING_EVENT_ID column now can be non-NULL to indicate the EVENT_ID value of the event

within which an event is nested, and NESTING_EVENT_TYPE is a new column indicating the type of

the nesting event.

The setup_instruments table now contains instruments with names that begin with stage and

statement. Corresponding to these instruments, the setup_timers table now contains rows with

NAME values of stage and statement that indicate the unit for stage and statement event timing.

The default unit for each is NANOSECOND.

These new tables store stage and statement events:

• events_stages_current: Current stage events

• events_stages_history: The most recent stage events for each thread

• events_stages_history_long: The most recent stage events overall

• events_statements_current: Current statement events

• events_statements_history: The most recent statement events for each thread

• events_statements_history_long: The most recent statement events overall

The setup_consumers table now contains consumer values with names corresponding to those

table names. These consumers may be used to filter collection of stage and statement events.

There are also summary tables that provide aggregated stage and statement information.

Application developers can use statement instrumentation to see in detail the statements generated

by an application, and how these statements are executed by the server. Stage instrumentation can

245

MySQL 5.6 Release Notes

be used to focus on particular parts of statements. This information may be useful to change how an

application issues queries against the database, to minimize the application footprint on the server,

and to improve application performance and scalability.

For more information, see Performance Schema Stage Event Tables, Stage Summary Tables,

Performance Schema Statement Event Tables, and Statement Summary Tables.

• The Performance Schema now provides statistics about connections to the server. When a client

connects, it does so under a particular user name and from a particular host. The Performance

Schema tracks connections per account (user name plus host name) and separately per user name

and per host name, using these tables:

• accounts: Connection statistics per client account

• hosts: Connection statistics per client host name

• users: Connection statistics per client user name

There are also summary tables that provide aggregated connection information.

It is good security practice to define a dedicated account per application, so that an application is

given privileges to perform only those actions that it needs during its operation. This also facilitates

monitoring because the information in the connection tables can be used by application developers

to see load statistics per application when deploying several applications against a given database

server.

For more information, see Performance Schema Connection Tables.

• Previously, the setup_objects table could be used only to specify by inclusion which objects

to instrument. There was no way to explicitly disable object instrumentation, such as to configure

instrumention for all tables except those in a particular database. Now the setup_objects table

includes an ENABLED column that indicates whether to instrument matching objects. This feature

improves the setup_objects table usability because it permits exclusion patterns.

The default table contents now include a row that disables instrumentation for tables in the mysql

database, which is a change from the previous default object instrumentation. This change is chosen

assuming that end users want to instrument application objects, not internal server tables. The change

reduces the default Performance Schema overhead because I/O and locks on mysql tables are not

instrumented.

The table also includes rows that disable instrumentation for tables in the INFORMATION_SCHEMA and

performance_schema databases. This is not a change in behavior because those tables were not

instrumented before, but these rows make the full object instrumentation defaults explicit.

• The Performance Schema now instruments sockets. This enables monitoring of network

communication to and from the server. Information collected includes network activity such as socket

instances, socket operations, and number of bytes transmitted and received.

The setup_instruments table now contains instruments with names that begin with wait/io/

socket. There is also an idle instrument used for idle events when a socket is waiting for the

next request from the client. Corresponding to the latter instrument, the setup_timers table now

246

MySQL 5.6 Release Notes

contains a row with a NAME value of idle that indicates the unit for idle event timing. The default unit

is MICROSECOND.

These new tables contain socket information:

• socket_instances: A real-time snapshot of the active connections to the MySQL server

• socket_summary_by_instance: Aggregate timer and byte count statistics generated by the

wait/io/socket/* instruments for all socket I/O operations, per socket instance

• socket_summary_by_event_name: Aggregate timer and byte count statistics generated by the

wait/io/socket/* instruments for all socket I/O operations, per socket instrument

The information in the socket tables can be used by application developers, particularly those

developing web-based applications, to assess the volume of network traffic directly attributable

to queries generated by their application. This can be particularly useful during development of

applications intended for large-scale implementations.

For more information, see The socket_instances Table, and Socket Summary Tables.

As a consequence of these changes, the Opening table thread state has been removed. The

Opening tables state remains and can be used instead. (See General Thread States.)

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the performance_schema database. (WL #4813,

WL #2515, WL #5342)

Security Notes

• For temporary tables created with the CREATE TEMPORARY TABLE statement, the privilege model has

changed.

Previously, the CREATE TEMPORARY TABLES privilege enabled users to create temporary tables with

the CREATE TEMPORARY TABLE statement. However, other operations on a temporary table, such

as INSERT, UPDATE, or SELECT, required additional privileges for those operations for the database

containing the temporary table, or for the nontemporary table of the same name.

To keep privileges for temporary and nontemporary tables separate, a common workaround for this

situation was to create a database dedicated to the use of temporary tables. Then for that database,

a user could be granted the CREATE TEMPORARY TABLES privilege, along with any other privileges

required for temporary table operations done by that user.

Now, the CREATE TEMPORARY TABLES privilege enables users to create temporary tables with CREATE

TEMPORARY TABLE, as before. However, after a session has created a temporary table, the server

performs no further privilege checks on the table. The creating session can perform any operation on the

table, such as DROP TABLE, INSERT, UPDATE, or SELECT.

One implication of this change is that a session can manipulate its temporary tables even if the

current user has no privilege to create them. Suppose that the current user does not have the CREATE

TEMPORARY TABLES privilege but is able to execute a DEFINER-context stored procedure that executes

with the privileges of a user who does have CREATE TEMPORARY TABLES and that creates a temporary

table. While the procedure executes, the session uses the privileges of the defining user. After the

procedure returns, the effective privileges revert to those of the current user, which can still see the

temporary table and perform any operation on it. (Bug #27480, Bug #11746602)

247

MySQL 5.6 Release Notes

• Statement logging has been modified so that passwords do not appear in plain text for the following

statements:

CREATE USER ... IDENTIFIED BY ...

GRANT ... IDENTIFIED BY ...

SET PASSWORD ...

Passwords in those statements are rewritten not to appear literally in statement text, for the general

query log, slow query log, and binary log. Rewriting does not apply to other statements.

For the general query log, password rewriting can be suppressed by starting the server with the --log-

raw option. This option may be useful for diagnostic purposes, to see the exact text of statements as

received by the server, but for security reasons is not recommended for production use.

One change you will notice is that statements that cannot be parsed (due, for example, to syntax errors)

are no longer written to the general query log because they cannot be known to be password free. Use

cases that require logging of all statements including those with errors should use the --log-raw

option, bearing in mind that this also bypasses password writing. (WL #5706)

Functionality Added or Changed

• Incompatible Change: In the audit plugin interface, the event_class member was removed from the

mysql_event_general structure and the calling sequence for the notification function was changed.

Originally, the second argument was a pointer to the event structure. The function now receives this

information as two arguments: an event class number and a pointer to the event. Corresponding to these

changes, MYSQL_AUDIT_INTERFACE_VERSION was increased to 0x0300.

The plugin_audit.h header file, and the NULL_AUDIT example plugin in the plugin/audit_null

directory were modified per these changes. See Writing Audit Plugins.

• Important Change; Replication: The RESET SLAVE statement has been extended with an ALL

keyword. In addition to deleting the master.info, relay-log.info, and all relay log files, RESET

SLAVE ALL also clears all connection information otherwise held in memory following execution of

RESET SLAVE. (Bug #11809016, Bug #11763210)

• Performance; InnoDB: At shutdown, MySQL can record the pages that are cached in the

InnoDB buffer pool, then reload those same pages upon restart. This technique can help

to quickly reach consistent throughput after a restart, without a lengthy warmup period. This

preload capability uses a compact save format and background I/O to minimize overhead on the

MySQL server. The basic dump/restore capability is enabled through the configuration options

innodb_buffer_pool_dump_at_shutdown and innodb_buffer_pool_load_at_startup.

Related configuration options such as innodb_buffer_pool_dump_now and

innodb_buffer_pool_load_now offer extra flexibility for advanced users to configure the MySQL

server for different workloads. See Saving and Restoring the Buffer Pool State for details. (Bug

#11765816, Bug #58819, WL #5712)

• Performance; InnoDB: When innodb_file_per_table is enabled, each InnoDB table is created

in its own tablespace file (.ibd file). As data inside the table grows, the .ibd file is extended, which is

an I/O operation that may create a bottleneck for busy systems with many InnoDB tables. For InnoDB

tables that are stored inside the system tablespace, the extension operation happens less frequently, as

space freed by DELETE or TRUNCATE operations within one table can be reused by another table.

MySQL 5.6 improves concurrency for extending InnoDB tablespace files (.ibd files), so that multiple

.ibd files can be extended simultaneously without blocking read or write operations performed by other

threads. (Bug #11763692, Bug #56433, WL #5654)

248

MySQL 5.6 Release Notes

• Performance; InnoDB: You can improve the efficiency of the InnoDB checksum feature by specifying

the configuration option innodb_checksum_algorithm=crc32, which turns on a faster checksum

algorithm. This option replaces the innodb_checksums option. Data written using the old checksum

algorithm (option value innodb) is fully upward-compatible; tablespaces modified using the new

checksum algorithm (option value crc32) cannot be downgraded to an earlier version of MySQL that

does not support the innodb_checksum_algorithm option. (Bug #11757757, Bug #49852, WL

#5652)

• Performance; InnoDB: The code that detects deadlocks in InnoDB transactions has been modified to

use a fixed-size work area rather than a recursive algorithm. The resulting detection operation is faster

as a result. You do not need to do anything to take advantage of this enhancement.

Under both the old and new detection mechanisms, you might encounter a search too deep error

that is not a true deadlock, but requires you to re-try the transaction the same way as with a deadlock.

(WL #5915)

• Performance; InnoDB: The InnoDB thread-scheduling code has been enhanced to work better with

greater than 16 threads. Where possible, atomic instructions are used. You control this feature by setting

the configuration option innodb_thread_concurrency to a nonzero value, and adjusting the value of

innodb_adaptive_max_sleep_delay. See Configuring Thread Concurrency for InnoDB for details.

(WL #5758)

• Performance; InnoDB: Work continues to offload flush operations from the InnoDB main thread,

doing them in the page_cleaner thread instead. The latest changes to the buffer pool flushing

algorithms can improve performance for some I/O-bound workloads, particularly in configurations

with multiple buffer pool instances. You control this feature by adjusting the settings for the

innodb_lru_scan_depth and innodb_flush_neighbors configuration options. To find the

optimal settings, test each combination of the above settings with both the Adaptive Hash Index and the

Doublewrite Buffer turned on and off. See Configuring Buffer Pool Flushing for more details. (WL #5580)

• Performance; InnoDB: This feature optionally moves the InnoDB undo log out of the system

tablespace into one or more separate tablespaces. The I/O patterns for the undo log make

these new tablespaces good candidates to move to SSD storage, while keeping the system

tablespace on hard disk storage. This feature is controlled by the configuration options

innodb_undo_directory, innodb_undo_tablespaces, and innodb_undo_logs (formerly

known as innodb_rollback_segments). Users cannot drop the separate tablespaces created to hold

InnoDB undo logs, or the individual segments inside those tablespaces.

MySQL instances configured this way are not downward-compatible; older versions of MySQL cannot

access the undo logs that reside in their own tablespace.

For details, see Undo Tablespaces. (WL #5535)

• InnoDB: InnoDB now permits concurrent reads while creating a secondary index. (Bug #11853126)

References: See also: Bug #11751388, Bug #11784056, Bug #11815600.

• InnoDB: The InnoDB redo log files now have a maximum combined size of 512GB, increased from

4GB. You can specify the larger values through the innodb_log_file_size option.

There is no special upgrade process or file format to take advantage of this enhancement. The bytes that

record the extra size information were already reserved in the InnoDB system tablespace. However, if

you develop applications that interact with the InnoDB logical sequence number (LSN) value, change

your code to use guaranteed 64-bit variables to store and compare LSN values, rather than 32-bit

variables. (Bug #11765780, Bug #58779, WL #5739)

249

MySQL 5.6 Release Notes

• InnoDB: InnoDB tables can now be created with character sets whose collation ID is greater than 255.

For example, the following InnoDB table can now be created, where formerly the collation ID of 359 was

beyond the range supported by InnoDB.

mysql> show collation like 'ucs2_vn_ci';

+------------+---------+-----+---------+----------+---------+

+------------+---------+-----+---------+----------+---------+

| ucs2_vn_ci | ucs2 | 359 | | | 8 |

+------------+---------+-----+---------+----------+---------+

1 row in set (0.00 sec)

mysql> CREATE TABLE two_byte_collation (c1 char(1) CHARACTER SET UCS2 COLLATE UCS2_VN_CI)

-> ENGINE = INNODB;

Query OK, 0 rows affected (0.16 sec)

This capability opens up InnoDB tables for use with a range of user-defined character sets. MySQL

predefined character sets have previously been limited to a maximum of 255, and now that restriction is

lifted. See Choosing a Collation ID for more information. (WL #5557)

• Replication: MySQL 5.6.1 added timestamps to the error messages shown in the Last_IO_Error

and Last_SQL_Error columns of the output of SHOW SLAVE STATUS. Now these timestamps

are shown in separate columns of their own, named Last_IO_Error_Timestamp and

Last_SQL_Error_Timestamp, respectively. (Bug #11765599, Bug #58584)

References: See also: Bug #43535, Bug #11752361.

• Replication: BEGIN, COMMIT, and ROLLBACK statements are now cached along with the statements

instead of being written when the cache is flushed to the binary log. This change does not affect DDL

statements—which are written into the statement cache, then immediately flushed—or Incident events

(which, along with Rotate events, are still written directly to the binary log). (WL #4832)

References: See also: Bug #57275, Bug #11764443.

• Microsoft Windows: The Windows installer now creates an item in the MySQL menu named MySQL

command line client - Unicode. This item invokes the mysql client with properties set to

communicate through the console to the MySQL server using Unicode. It passes the --default-

character-set=utf8 option to mysql and sets the font to the Lucida Console Unicode-

compatible font. See Unicode Support on Windows. (WL #5826)

• Following EXPLAIN EXTENDED, a change has been made to the transformed query displayed by SHOW

WARNINGS. Each SELECT part now is preceded by the id value from the associated EXPLAIN output

row. This makes it easier to see the correspondence between those rows and parts of the transformed

query. For example, this query:

EXPLAIN EXTENDED SELECT 36 FROM DUAL

results in:

/* select#1 */ select 36 from dual

And this query:

EXPLAIN EXTENDED SELECT a FROM t

WHERE a IN (SELECT b FROM u UNION SELECT c from v)

results in:

/* select#1 */ select a from t where a in (/* select#2 */

select b from u union /* select#3 */ select c from v);

250

MySQL 5.6 Release Notes

(Bug #13035597)

• Several memory allocation calls were eliminated, resulting in improved performance. (Bug #12552221)

• CMake configuration support on Linux now provides a boolean ENABLE_GCOV option to control whether

to include support for gcov. (Bug #12549572)

• Previously, Performance Schema instrumentation for both the binary log and the relay log used these

instruments:

wait/io/file/sql/binlog

wait/io/file/sql/binlog_index

wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_index

wait/synch/cond/sql/MYSQL_BIN_LOG::update_cond

Now instrumentation for the relay log uses these instruments, which makes it possible to distinguish

binary log and relay log events:

wait/io/file/sql/relaylog

wait/io/file/sql/relaylog_index

wait/synch/mutex/sql/MYSQL_RELAY_LOG::LOCK_index

wait/synch/cond/sql/MYSQL_RELAY_LOG::update_cond

(Bug #59658, Bug #11766528)

• A new server option, --plugin-load-add, complements the --plugin-load option. --plugin-

load-add adds a plugin or plugins to the set of plugins to be loaded at startup. The argument format is

the same as for --plugin-load. --plugin-load-add can be used to avoid specifying a large set of

plugins as a single long unwieldy --plugin-load argument.

--plugin-load-add can be given in the absence of --plugin-load, but any instance of --

plugin-load-add that appears before --plugin-load. has no effect because --plugin-load

resets the set of plugins to load.

This change affects the output of mysqld --verbose --help in that a value for plugin-load is no

longer printed. (Bug #59026, Bug #11766001)

• When invoked with the --auto-generate-sql option, mysqlslap dropped the schema specified with

the --create-schema option at the end of the test run, which may have been unexpected by the user.

mysqlslap now has a --no-drop option that prevents any schema created during the test run from

being dropped. (Bug #58090, Bug #11765157)

• The server now exposes SSL certificate expiration dates through the Ssl_server_not_before

and Ssl_server_not_after status variables. Both variables have values in ANSI time format (for

example, Sep 12 16:22:06 2013 GMT), or are blank for non-SSL connections. (Bug #57648, Bug

#11764778)

• Previously, TEMPORARY tables created with CREATE TEMPORARY TABLES used the default storage

engine unless the definition included an explicit ENGINE option. (The default engine is the value of

the default_storage_engine system variable.) Since MySQL 5.5.5, when the default storage

engine was changed from the nontransactional MyISAM engine to the transactional InnoDB engine,

TEMPORARY tables have incurred the overhead of transactional processing.

To permit the default storage engine for TEMPORARY tables to be set independently of the default engine

for permanent tables, the server now supports a default_tmp_storage_engine system variable.

For example, to create TEMPORARY tables as nontransactional tables by default, start the server with

--default_tmp_storage_engine=MyISAM. The storage engine for TEMPORARY tables can still be

251

MySQL 5.6 Release Notes

specified on an individual basis by including an ENGINE option in table definitions. (Bug #49232, Bug

#11757216)

• Previously, for MySQL binaries linked against OpenSSL, if an SSL key file supplied to the MySQL server

or a MySQL client program (using the --ssl-key option) was protected by a passphrase, the program

would prompt the user for the passphrase. This is now also the case for MySQL binaries linked against

yaSSL. (Bug #44559, Bug #11753167)

• The mysql client program now has a --binary-mode option that helps when processing

mysqlbinlog output that may contain BLOB values. By default, mysql translates \r\n in statement

strings to \n and interprets \0 as the statement terminator. --binary-mode disables both features. It

also disables all mysql commands except charset and delimiter in noninteractive mode (for input

piped to mysql or loaded using the source command). (Bug #33048, Bug #11747577)

• MySQL binaries linked against OpenSSL (but not yaSSL) now support certificate revocation lists for SSL

connections:

• The MySQL server supports the ssl_crl and ssl_crlpath system variables, which indicate the

revocation list file or directory containing such files.

• MySQL client programs that support SSL recognize --ssl-crl and --ssl-crlpath options for

specifying a revocation list file or directory containing such files.

• The CHANGE MASTER TO statement has MASTER_SSL_CRL and MASTER_SSL_CRLPATH options

for specifying revocation list information to use when the slave connects to the master. The

mysql.slave_master_info file has two more rows to store the values of these options. The SHOW

SLAVE STATUS statement has two more columns to display the values of these options.

The mysql_options() C API function has MYSQL_OPT_SSL_CRL and MYSQL_OPT_SSL_CRLPATH

options for specifying revocation list information to use when the client connects to the master. In

addition, mysql_options() now also supports MYSQL_OPT_SSL_CA, MYSQL_OPT_SSL_CAPATH,

MYSQL_OPT_SSL_CERT, MYSQL_OPT_SSL_CIPHER, and MYSQL_OPT_SSL_KEY options for

specifying other SSL parameters.

(Bug #31224, Bug #11747191)

• mysqld now has an --ignore-db-dir option that tells the server to ignore a given name for purposes

of the SHOW DATABASES statement or INFORMATION_SCHEMA tables. For example, if a MySQL

configuration locates the data directory at the root of a file system on Unix, the system might create a

lost+found directory there that the server should ignore. Starting the server with --ignore-db-

dir=lost+found causes that name not to be listed as a database.

To specify more than one name, use this option multiple times, once for each name. Specifying the

option with an empty value (that is, as --ignore-db-dir=) resets the directory list to the empty list.

Instances of this option given at server startup are used to set the ignore_db_dirs system variable.

In addition to directories named by --ignore-db-dir, directories having a name that begins with a

period are ignored. (Bug #22615, Bug #11746029)

• Client programs now display more information for SSL errors to aid in diagnosis and debugging of

connection problems. (Bug #21287, Bug #11745920)

• Some plugins operate in such a matter that they should be loaded at server startup, and not loaded or

unloaded at runtime. The plugin API now supports marking plugins this way. The st_mysql_plugin

structure now has a flags member, which can be set to the OR of the applicable flags. The

PLUGIN_OPT_NO_INSTALL flag indicates that the plugin cannot be loaded at runtime with the INSTALL

252

MySQL 5.6 Release Notes

PLUGIN statement. This is appropriate for plugins that must be loaded at server startup with the --

plugin-load option. The PLUGIN_OPT_NO_UNINSTALL flag indicates that the plugin cannot be

unloaded at runtime with the UNINSTALL PLUGIN statement.

The new member changes the interface, so the plugin interface version,

MYSQL_PLUGIN_INTERFACE_VERSION, has been incremented from 0x0102 to 0x0103. Plugins that

require access to the new member must be recompiled to use version 0x0103 or higher. (WL #5973)

• A new utility, mysql_plugin, enables MySQL administrators to manage which plugins a MySQL server

loads. It provides an alternative to manually specifying the --plugin-load option at server startup

or using the INSTALL PLUGIN and UNINSTALL PLUGIN statements at runtime. See mysql_plugin —

Configure MySQL Server Plugins. (WL #5710)

• The following items are deprecated and will be removed in a future MySQL release. Where alternatives

are shown, applications should be updated to use them.

• The innodb_table_monitor table. Similar information can be obtained from InnoDB

INFORMATION_SCHEMA tables. See INFORMATION_SCHEMA InnoDB Tables.

• The innodb_locks_unsafe_for_binlog system variable.

• The innodb_stats_sample_pages system variable. Use

innodb_stats_transient_sample_pages instead.

• The innodb_use_sys_malloc and the innodb_additional_mem_pool_size system variables.

(WL #5533)

• The undocumented --all option for perror has been removed. Also, perror no longer displays

messages for BDB error codes. (WL #5914)

• MySQL now includes support for manipulating IPv6 network addresses and for validating IPv4 and IPv6

addresses:

• The INET6_ATON() and INET6_NTOA() functions convert between string and numeric forms of IPv6

addresses. Because numeric-format IPv6 addresses require more bytes than the largest integer type,

the representation uses the VARBINARY data type.

• The IS_IPV4() and IS_IPV6() functions test whether a string value represents a valid IPv4 or IPv6

address. The IS_IPV4_COMPAT() and IS_IPV4_MAPPED() functions test whether a numeric-format

value represents a valid IPv4-compatible or IPv4-mapped address.

• No changes were made to the INET_ATON() or INET_NTOA() functions that manipulate IPv4

addresses.

IS_IPV4() is more strict than INET_ATON() about what constitutes a valid IPv4 address, so it may

be useful for applications that need to perform strong checks against invalid values. Alternatively, use

INET6_ATON() to convert IPv4 addresses to internal form and check for a NULL result (which indicates

an invalid address). INET6_ATON() is equally strong as IS_IPV4() about checking IPv4 addresses.

(WL #5787)

• The max_allowed_packet system variable now controls the maximum size of parameter values that

can be sent with the mysql_stmt_send_long_data() C API function.

• The NULL_AUDIT example plugin in the plugin/audit_null directory has been updated to count

instances of events in the MYSQL_AUDIT_CONNECTION_CLASS event class. See Writing Audit Plugins.

253

MySQL 5.6 Release Notes

Bugs Fixed

• Security Fix: A security bug was fixed. (Bug #59533)

• Incompatible Change: For socket I/O, an optimization for the case when the server used alarms for

timeouts could cause a slowdown when socket timeouts were used instead.

The fix for this issue results in several changes:

• Previously, timeouts applied to entire packet-level send or receive operations. Now timeouts apply to

individual I/O operations at a finer level, such as sending 10 bytes of a given packet.

• The handling of packets larger than max_allowed_packet has changed. Previously, if an

application sent a packet bigger than the maximum permitted size, or if the server failed to allocate

a buffer sufficiently large to hold the packet, the server kept reading the packet until its end, then

skipped it and returned an ER_NET_PACKET_TOO_LARGE error. Now the server disconnects the

session if it cannot handle such large packets.

• On Windows, the default value for the MYSQL_OPT_CONNECT_TIMEOUT option to mysql_options()

is no longer 20 seconds. Now the default is no timeout (infinite), the same as on other platforms.

• Building and running MySQL on POSIX systems now requires support for poll() and O_NONBLOCK.

These should be available on any modern POSIX system.

(Bug #54790, Bug #36225, Bug #11762221, Bug #51244, Bug #11758972)

• Incompatible Change: The mysql_affected_rows() C API function returned 3 (instead of 2) for

INSERT ... ON DUPLICATE KEY UPDATE statements where there was a duplicated key value.

Now the affected-rows value per row is 1 if the row is inserted as a new row, 2 if an existing row is

updated, and 0 if an existing row is set to its current values. If you specify the CLIENT_FOUND_ROWS

flag to mysql_real_connect() when connecting to mysqld, the affected-rows value is 1 (not 0) if an

existing row is set to its current values. (Bug #46675, Bug #11754979)

• Incompatible Change: Handling of a date-related assertion was modified. A consequence of this

change is that several functions become more strict when passed a DATE() function value as

their argument and reject incomplete dates with a day part of zero. These functions are affected:

CONVERT_TZ(), DATE_ADD(), DATE_SUB(), DAYOFYEAR(), LAST_DAY(), TIMESTAMPDIFF(),

TO_DAYS(), TO_SECONDS(), WEEK(), WEEKDAY(), WEEKOFYEAR(), YEARWEEK().

It was later determined that stricter handling is unnecessary for LAST_DAY(), which was reverted to

permit a zero day part in MySQL 5.6.5.

References: See also: Bug #13458237.

• Performance; InnoDB: This fix improves the performance of operations on VARCHAR(N) columns in

InnoDB tables, where N is declared as a large value but the actual string values in the table are short.

(Bug #12835650)

• Performance; InnoDB: The mechanism that InnoDB uses to detect if the MySQL server is idle was

made more accurate, to avoid slowdown due to flush operations that normally occur when no other

activity is taking place. The mechanism now considers that the server is not idle if there are pending read

requests for the InnoDB buffer pool. (Bug #11766123, Bug #59163)

254

MySQL 5.6 Release Notes

• InnoDB; Replication: Trying to update a column, previously set to NULL, of an InnoDB table with no

primary key caused replication to fail on the slave with Can't find record in 'table'.

Note

This issue was inadvertently reintroduced in MySQL 5.6.6, and fixed again in

MySQL 5.6.12.

(Bug #11766865, Bug #60091)

References: See also: Bug #16566658.

• InnoDB: The DATA_LENGTH column in the INFORMATION_SCHEMA.TABLES table now correctly reports

the on-disk sizes of tablespaces for InnoDB compressed tables. (Bug #12770537)

• InnoDB: A failed CREATE INDEX operation for an InnoDB table could result in some memory being

allocated but not freed. This memory leak could affect tables created with the ROW_FORMAT=DYNAMIC or

ROW_FORMAT=COMPRESSED setting. (Bug #12699505)

• InnoDB: With the configuration settings innodb_file_per_table=1 and

innodb_file_format=Barracuda, inserting a column value greater than half the page size, and

including that column in a secondary index, could cause a crash when that column value was updated.

(Bug #12637786)

• InnoDB: The underlying tables to support the InnoDB persistent statistics feature were renamed and

moved into the mysql database. innodb.table_stats became mysql.innodb_table_stats, and

innodb.index_stats became mysql.innodb_index_stats. (Bug #12604399)

• InnoDB: The server could halt if InnoDB interpreted a very heavy I/O load for 15 minutes or more as

an indication that the server was hung. This change fixes the logic that measures how long InnoDB

threads were waiting, which formerly could produce false positives. (Bug #11877216, Bug #11755413,

Bug #47183)

• InnoDB: With the setting lower_case_table_names=2, inserts into InnoDB tables covered by

foreign key constraints could fail after a server restart. (Bug #11831040, Bug #60196, Bug #60909)

• InnoDB: If the MySQL Server crashed immediately after creating an InnoDB table, attempting to access

the table after restart could cause another crash. The issue could occur if the server halted after InnoDB

created the primary index for the table, but before the index definition was recorded in the MySQL

metadata. (Bug #11766824, Bug #60042)

• InnoDB: If the server crashed while an XA transaction was prepared but not yet committed, the

transaction could remain in the system after restart, and cause a subsequent shutdown to hang. (Bug

#11766513, Bug #59641)

• InnoDB: The MySQL server could hang during CREATE TABLE, OPTIMIZE TABLE, or ALTER TABLE

or other DDL operation that performs a table copy for an InnoDB table, if such operations were

performed by multiple sessions simultaneously. The error was reported as:

InnoDB: Error: semaphore wait has lasted > 600 seconds

(Bug #11760042, Bug #52409)

• InnoDB: With the setting lower_case_table_names=2, inserts into InnoDB tables covered by

foreign key constraints could fail after a server restart. This is a similar problem to the foreign key error in

Bug #11831040 / Bug #60196 / Bug #60909, but with a different root cause and occurring on OS X.

255

MySQL 5.6 Release Notes

• Partitioning: The internal get_partition_set() function did not take into account the possibility that

a key specification could be NULL in some cases. (Bug #12380149)

• Partitioning: When executing a row-ordered retrieval index merge, the partitioning handler used

memory from that allocated for the table, rather than that allocated to the query, causing table object

memory not to be freed until the table was closed. (Bug #11766249, Bug #59316)

• Partitioning: Attempting to use ALTER TABLE ... EXCHANGE PARTITION to exchange a view with

a (nonexistent) partition of a table that was not partitioned caused the server to crash. (Bug #11766232,

Bug #60039)

• Partitioning: Auto-increment columns of partitioned tables were checked even when they were not

being written to. In debug builds, this could lead to a server crash. (Bug #11765667, Bug #58655)

• Partitioning: The UNIX_TIMESTAMP() function was not treated as a monotonic function for purposes

of partition pruning. (Bug #11746819, Bug #28928)

• Partitioning: A problem with a previous fix for poor performance of INSERT ON DUPLICATE KEY

UPDATE statements on tables having many partitions caused the handler function for reading a row from

a specific index to fail to store the ID of the partition last used. This caused some statements to fail with

Can't find record errors. (Bug #59297, Bug #11766232)

References: This issue is a regression of: Bug #52455.

• Replication: A mistake in thread cleanup could cause a replication master to crash. (Bug #12578441)

• Replication: When using row-based replication and attribute promotion or demotion (see Replication of

Columns Having Different Data Types), memory allocated internally for conversion of BLOB columns was

not freed afterwards. (Bug #12558519)

• Replication: A memory leak could occur when re-creating a missing master info repository, because a

new I/O cache used for a reference to the repository was re-created when the repository was re-created,

but the previous cache was never removed. (Bug #12557307)

• Replication: A race condition could occur between a user thread and the SQL thread when both tried to

read the same memory before its value was safely set. This issue has now been corrected.

In addition, internal functions relating to creation of and appending to log events, when storing data, used

memory local to the functions which was freed when the functions returned. As part of the fix for this

problem, the output of SHOW SLAVE STATUS has been modified such that it no longer refers to files

or file names in the accompanying status message, but rather contains one of the messages Making

temporary file (append) before replaying LOAD DATA INFILE or Making temporary

file (create) before replaying LOAD DATA INFILE. (Bug #12416611)

• Replication: The name of the Ssl_verify_server_cert column in the

mysql.slave_master_info table was misspelled as Ssl_verify_servert_cert. (Bug

#12407446, Bug #60988)

• Replication: When mysqlbinlog was invoked using --base64-output=decode-row and --

start-position=pos, (where pos is a point in the binary log past the format description log event), a

spurious error of the type shown here was generated:

malformed binlog: it does not contain any Format_description_log_event...

However, since there is nothing unsafe about not printing the format description log event, the error has

been removed for this case. (Bug #12354268)

256

MySQL 5.6 Release Notes

• Replication: A failed CREATE USER statement was mistakenly written to the binary log. (Bug

#11827392, Bug #60082)

• Replication: It is no longer possible to change the storage engine used by the

mysql.slave_master_info and mysql.slave_relay_log_info tables while replication is

running. This means that, to make replication crash-safe, you must make sure that both of these tables

use a transactional storage engine before starting replication.

For more information, see Relay Log and Replication Metadata Repositories, and Options for Logging

Replica Status to Tables. (Bug #11765887, Bug #58897)

• Replication: A transaction was written to the binary log even when it did not update any

nontransactional tables. (Bug #11763471, Bug #56184)

References: See also: Bug #11763126, Bug #55789.

• Replication: mysqlbinlog using the --raw option did not function correctly with binary logs from

MySQL Server versions 5.0.3 and earlier. (Bug #11763265, Bug #55956)

• Replication: Retrying a transaction on the slave could insert extra data into nontransactional tables.

(Bug #11763126, Bug #55789)

References: See also: Bug #11763471, Bug #56184.

• Replication: Typographical errors appeared in the text of several replication error messages. (The word

“position” was misspelled as “postion”.) (Bug #11762616, Bug #55229)

• Replication: Temporary deadlocks in the slave SQL thread could cause unnecessary Deadlock

found when trying to get lock; try restarting transaction error messages to be

logged on the slave.

Now in such cases, only a warning is logged unless slave_transaction_retries has been

exceeded by the number of such warnings for a given transaction. (Bug #11748510, Bug #36524)

• Replication: When a slave requested a binary log file which did not exist on the master, the slave

continued to request the file regardless. This caused the slave's error log to be flooded with low-level

EE_FILENOTFOUND errors (error code 29) from the master. (Bug #11745939, Bug #21437)

• Replication: If a LOAD DATA statement—replicated using statement-based replication—featured a SET

clause, the name-value pairs were regenerated using a method (Item::print()) intended primarily for

generating output for statements such as EXPLAIN EXTENDED, and which cannot be relied on to return

valid SQL. This could in certain cases lead to a crash on the slave.

To fix this problem, the server now names each value in its original, user-supplied form, and uses that to

create LOAD DATA statements for statement-based replication. (Bug #60580, Bug #11902767)

References: See also: Bug #34283, Bug #11752526, Bug #43746.

• Replication: Error 1590 (ER_SLAVE_INCIDENT) caused the slave to stop even when it was started with

--slave-skip-errors=1590. (Bug #59889, Bug #11768580, Bug #11799671)

• Replication: Using the --server-id option with mysqlbinlog could cause format description log

events to be filtered from the binary log, leaving mysqlbinlog unable to read the remainder of the log.

Now such events are always read without regard to the value of this option.

As part of the fix for this problem, mysqlbinlog now also reads rotate log events without regard to the

value of --server-id. (Bug #59530, Bug #11766427)

257

MySQL 5.6 Release Notes

• Replication: A failed DROP DATABASE statement could break statement-based replication. (Bug

#58381, Bug #11765416)

• Replication: Processing of corrupted table map events could cause the server to crash. This was

especially likely if the events mapped different tables to the same identifier, such as could happen due to

Bug #56226.

Now, before applying a table map event, the server checks whether the table has already been mapped

with different settings, and if so, an error is raised and the slave SQL thread stops. If it has been

mapped with the same settings, or if the table is set to be ignored by filtering rules, there is no change in

behavior: the event is skipped and IDs are not checked. (Bug #44360, Bug #11753004)

References: See also: Bug #56226, Bug #11763509.

• OS X: Compilation failed on OS X 10.7 (Lion) with a warning: Implicit declaration of

function 'pthread_init' (Bug #12779790)

• Microsoft Windows: Adding support for Windows authentication to libmysqlclient introduced a link

dependency on the system Secur32 library. The Microsoft Visual C++ link information now pulls in this

library automatically. (Bug #12612143)

• Microsoft Windows: On Windows, the server rejected client connections if no DNS server was

available. (Bug #12325375)

• Microsoft Windows: On Windows, the authentication_string column recently added to the

mysql.user table caused the Configuration Wizard to fail. (Bug #59038, Bug #11766011)

• The Performance Schema caused a bottleneck for LOCK_open. (Bug #12993572)

• mysqld_safe ignored any value of plugin_dir specified in my.cnf files. (Bug #12925024)

• The metadata locking subsystem added too much overhead for INFORMATION_SCHEMA queries that

were processed by opening only .frm or .TRG files and had to scan many tables. For example, SELECT

COUNT(*) FROM INFORMATION_SCHEMA.TRIGGERS was affected. (Bug #12828477)

• The result for ANY subqueries with nested joins could be missing rows. (Bug #12795555)

• With profiling disabled or not compiled in, set_thd_proc_info() unnecessarily checked file name

lengths. (Bug #12756017)

References: This issue is a regression of: Bug #59273.

• Compiling the server with maintainer mode enabled failed for gcc 4.6 or higher. (Bug #12727287)

• For prepared statements, an OK could be sent to the client if the prepare failed due to being killed. (Bug

#12661349)

• Some Valgrind warnings were corrected:

• For the SUBSTRING(), LEFT(), RIGHT(), LPAD(), RPAD(), and REPEAT() functions, a missing

NULL value check was corrected.

• For the LIKE operator, an attempt to use an uninitialized string buffer in the case of an empty wildcard

was corrected.

(Bug #12634989, Bug #59851, Bug #11766684)

• For debug builds, a field-type check raised an assertion if the type was MYSQL_TYPE_NULL. (Bug

#12620084)

258

MySQL 5.6 Release Notes

• With index condition pushdown enabled, a crash could occur due to an invalid end-of-range value. (Bug

#12601961)

• The option-parsing code for empty strings leaked memory. (Bug #12589928)

• The server could fail to free allocated memory when INSERT DELAYED was used with binary logging

enabled. (Bug #12538873)

• A DBUG_ASSERT added by Bug #11792200 was overly aggressive in raising assertions. (Bug

#12537160)

References: See also: Bug #11792200.

• In some cases, memory allocated for Query_tables_list::sroutines() was not freed properly.

(Bug #12429877)

• After the fix for Bug #11889186, MAKEDATE() arguments with a year part greater than 9999 raised an

assertion. (Bug #12403504)

References: This issue is a regression of: Bug #11889186.

• An assertion could be raised due to a missing NULL value check in

Item_func_round::fix_length_and_dec(). (Bug #12392636)

• Assignments to NEW.var_name within triggers, where var_name had a BLOB or TEXT type, were not

properly handled and produced incorrect results. (Bug #12362125)

• An assertion could be raised if Index Condition Pushdown code pushed down an index condition

containing a subquery. (Bug #12355958)

• XA COMMIT could fail to clean up the error state if it discovered that the current XA transaction had to be

rolled back. Consequently, the next XA transaction could raise an assertion when it checked for proper

cleanup of the previous transaction. (Bug #12352846)

• An assertion could be raised during two-phase commits if the binary log was used as the transaction

coordinator log. (Bug #12346411)

• InnoDB could add temporary index information to INFORMATION_SCHEMA, which could raise an

assertion. (Bug #12340873)

• mysql_list_fields() returned incorrect character set information for character columns of views.

(Bug #12337762)

• A too-strict assertion could cause a server crash. (Bug #12321461)

• mysql_upgrade did not properly upgrade the authentication_string column of the mysql.user

table. (Bug #11936829)

• The optimizer sometimes chose a forward index scan followed by a filesort to reverse the order rather

than scanning the index in reverse order. (Bug #11882131)

• Previously, an inappropriate error message was produced if a multiple-table update for an InnoDB

table with a clustered primary key would update a table through multiple aliases, and perform an update

that may physically move the row in at least one of these aliases. Now the error message is: Primary

key/partition key update is not permitted since the table is updated both as

'tbl_name1' and 'tbl_name2' (Bug #11882110)

References: See also: Bug #11764529.

259

MySQL 5.6 Release Notes

• With index condition pushdown enabled, queries that used STRAIGHT_JOIN on data that included NULL

values could return incorrect results. (Bug #11873324)

• InnoDB invoked some zlib functions without proper initialization. (Bug #11849231)

• Division of large numbers could cause stack corruption. (Bug #11792200)

• Corrected a condition that produced an InnoDB message in the error log, unlock row could not

find a 3 mode lock on the record. This situation could occur with a combination of a subquery

and a FOR UPDATE clause under the READ UNCOMMITTED isolation level. The fix also improves the

debuggability of such messages by including the original SQL statements that caused them. (Bug

#11766322, Bug #59410)

• With Valgrind enabled, InnoDB semaphore wait timeouts were too low and could expire. (Bug

#11765460)

• CHECK TABLE and REPAIR TABLE failed to find problems with MERGE tables that had underlying tables

missing or with the wrong storage engine. Issues were reported only for the first underlying table. (Bug

#11754210)

• (5 DIV 2) and (5.0 DIV 2) produced different results (2 versus 3) because the result of the latter

expression was not truncated before conversion to integer. This differed from the behavior in MySQL 5.0

and 5.1. Now both expressions produce 2. (Bug #61676, Bug #12711164)

• The server failed to compile if partitioning support was disabled. (Bug #61625, Bug #12694147)

• ALTER TABLE {MODIFY|CHANGE} ... FIRST did nothing except rename columns if the old and new

versions of the table had exactly the same structure with respect to column data types. As a result, the

mapping of column name to column data was incorrect. The same thing happened for ALTER TABLE

DROP COLUMN ... ADD COLUMN statements intended to produce a new version of the table with

exactly the same structure as the old version. (Bug #61493, Bug #12652385)

• Incorrect handling of metadata locking for FLUSH TABLES WITH READ LOCK for statements requiring

prelocking caused two problems:

• Execution of any data-changing statement that required prelocking (that is, involved a stored

function or trigger) as part of a transaction slowed down somewhat all subsequent statements in

the transaction. Performance in a transaction that periodically involved such statements gradually

degraded over time.

• Execution of any data-changing statement that required prelocking as part of a transaction prevented

a concurrent FLUSH TABLES WITH READ LOCK from proceeding until the end of the transaction

rather than at the end of the particular statement.

(Bug #61401, Bug #12641342)

• A problem introduced in MySQL 5.5.11 caused very old (MySQL 4.0) clients to be unable to connect to

the server. (Bug #61222, Bug #12563279)

• The fractional part of the “Queries per second” value could be displayed incorrectly in MySQL status

output (for example, in the output from mysqladmin status or the mysql STATUS command). (Bug

#61205, Bug #12565712)

• The mysql-log-rotate script was updated because it referred to deprecated MySQL options. (Bug

#61038, Bug #12546842)

• Using CREATE EVENT IF NOT EXISTS for an event that already existed and was enabled caused

multiple instances of the event to run. (Bug #61005, Bug #12546938)

260

MySQL 5.6 Release Notes

• If a statement ended with mismatched quotes, the server accepted the statement and interpreted

whatever was after the initial quote as a text string. (Bug #60993, Bug #12546960)

• LOAD DATA incorrectly parsed relative data file path names that ascended more than three levels in the

file system and as a consequence was unable to find the file. (Bug #60987, Bug #12403662)

• Fixed “shift count greater than width of type” compilation warnings. (Bug #60908, Bug #12402772)

References: See also: Bug #12561303.

• Table I/O for the table_io_waits_summary_by_index_usage Performance Schema table was

counted as using no index for UPDATE and DELETE statements, even when an index was used. (Bug

#60905, Bug #12370950)

• An internal client macro reference was removed from the client_plugin.h header file. This reference

made the file unusable. (Bug #60746, Bug #12325444)

• Comparison of a DATETIME stored program variable and NOW() resulted in “Illegal mix of collations

error” when character_set_connection was set to utf8. (Bug #60625, Bug #11926811)

• Selecting from a view for which the definition included a HAVING clause failed with an error:

1356: View '...' references invalid table(s) or column(s)

or function(s) or definer/invoker of view lack rights to use them

(Bug #60295, Bug #11829681)

• CREATE TABLE syntax permits specification of a STORAGE {DEFAULT|DISK|MEMORY} option.

However, this value was not written to the .frm file, so that a subsequent CREATE TABLE ... LIKE

for the table did not include that option.

Also, ALTER TABLE of a table that had a tablespace incorrectly destroyed the tablespace. (Bug #60111,

Bug #11766883, Bug #34047, Bug #11747789)

• The mysql_load_plugin() C API function did not clear the previous error. (Bug #60075, Bug

#11766854)

• For repeated invocation of some stored procedures, the server consumed memory that it did not release

until the connection terminated. (Bug #60025, Bug #11848763)

• The server permitted max_allowed_packet to be set lower than net_buffer_length, which does

not make sense because max_allowed_packet is the upper limit on net_buffer_length values.

Now a warning occurs and the value remains unchanged. (Bug #59959, Bug #11766769)

• The server did not check for certain invalid out of order sequences of XA statements, and these

sequences raised an assertion. (Bug #59936, Bug #11766752, Bug #12348348)

• Index condition pushdown code accessed an uninitialized variable. (Bug #59843, Bug #11766678)

• For unknown users, the native password plugin reported incorrectly that no password had been specified

even when it had. (Bug #59792, Bug #11766641)

• SELECT DISTINCT with a deterministic stored function in the WHERE clause could produce incorrect

results. (Bug #59736, Bug #11766594)

• Setting optimizer_join_cache_level to 3 or greater raised an assertion for some queries. (Bug

#59651, Bug #11766522)

261

MySQL 5.6 Release Notes

• Previously, Performance Schema table columns that held byte counts were BIGINT UNSIGNED. These

were changed to BIGINT (signed). This makes it easier to perform calculations that compute differences

between columns. (Bug #59631, Bug #11766504)

• A missing variable initialization for Item_func_set_user_var objects could raise an assertion. (Bug

#59527, Bug #11766424)

• For some queries, the optimizer performed range analysis too many times for the same index. (Bug

#59415, Bug #11766327)

• With the conversion from GNU autotools to CMake for configuring MySQL, the USE_SYMDIR

preprocessor symbol was omitted. This caused failure of symbolic links (described at Using Symbolic

Links). (Bug #59408, Bug #11766320)

• An incorrect max_length value for YEAR values could be used in temporary result tables for UNION,

leading to incorrect results. (Bug #59343, Bug #11766270)

• In Item_func_in::fix_length_and_dec(), a Valgrind warning for uninitialized values was

corrected. (Bug #59270, Bug #11766212)

• An invalid pathname argument for the --defaults-extra-file option of MySQL programs caused a

program crash. (Bug #59234, Bug #11766184)

• In Item_func_month::val_str(), a Valgrind warning for a too-late NULL value check was

corrected. (Bug #59166, Bug #11766126)

• In Item::get_date, a Valgrind warning for a missing NULL value check was corrected. (Bug #59164,

Bug #11766124)

• In extract_date_time(), a Valgrind warning for a missing end-of-string check was corrected. (Bug

#59151, Bug #11766112)

• Some tables were not instrumented by the Performance Schema even though they were listed in the

setup_objects table. (Bug #59150, Bug #11766111)

• In string context, the MIN() and MAX() functions did not take into account the unsignedness of a

BIGINT UNSIGNED argument. (Bug #59132, Bug #11766094)

• In Item_func::val_decimal, a Valgrind warning for a missing NULL value check was corrected.

(Bug #59125, Bug #11766087)

• In ROUND() calculations, a Valgrind warning for uninitialized memory was corrected. (Bug #58937, Bug

#11765923)

References: This issue is a regression of: Bug #33143.

• The range created by the optimizer when OR-ing two conditions could be incorrect, causing incorrect

query results. (Bug #58834, Bug #11765831)

• Valgrind warnings caused by comparing index values to an uninitialized field were corrected. (Bug

#58705, Bug #11765713)

• As a side effect of optimizing condition AND TRUE or condition OR FALSE, MySQL for certain

subqueries forgot that the columns used by the condition needed to be read, which raised an assertion in

debug builds. (Bug #58690, Bug #11765699)

• CREATE TRIGGER and DROP TRIGGER can change the prelocking list of stored routines, but the routine

cache did not detect such changes, resulting in routine execution with an inaccurate locking list. (Bug

#58674, Bug #11765684)

262

MySQL 5.6 Release Notes

• In Item_func_str_to_date::val_str, a Valgrind warning for an uninitialized variable was

corrected. (Bug #58154, Bug #11765216)

• The code for PROCEDURE ANALYSE() had a missing DBUG_RETURN statement, which could cause a

server crash in debug builds. (Bug #58140, Bug #11765202)

• LOAD DATA errors could leak I/O cache memory. (Bug #58072, Bug #11765141)

• For LOAD DATA, multibyte character sequences could be pushed onto a stack too small to

accommodate them. (Bug #58069, Bug #11765139)

• The embedded server crashed when argc = 0. (Bug #57931, Bug #12561297)

• An assertion could be raised in Item_func_int_val::fix_num_length_and_dec() due to

overflow for geometry functions. (Bug #57900, Bug #11764994)

• An assertion was raised if a statement tried to upgrade a metadata lock while there was an active FLUSH

TABLE tbl_list WITH READ LOCK statement. Now if a statement tries to upgrade a metadata lock

in this situation, the server returns an ER_TABLE_NOT_LOCKED_FOR_WRITE error to the client. (Bug

#57649, Bug #11764779)

• The optimizer sometimes requested ordered access from a storage engine when ordered access was

not required. (Bug #57601, Bug #11764737)

• An embedded client aborted rather than issuing an error message if it issued a TEE command (\T

file_name) and the directory containing the file did not exist. This occurred because the wrong error

handler was called. (Bug #57491, Bug #11764633)

• ALTER EVENT could change the event status. (Bug #57156, Bug #11764334)

• For an outer join with a NOT IN subquery in the WHERE clause, a null left operand to the NOT IN

returned was treated differently than a literal NULL operand. (Bug #56881, Bug #11764086)

• Threads blocked in the waiting for table metadata state were not visible in

performance_schema.THREADS or SHOW PROFILE. (Bug #56475, Bug #11763728)

• With prepared statements, the server could attempt to send result set metadata after the table had been

closed. (Bug #56115, Bug #11763413)

• Table objects associated with one session's optimizer structures could be closed after being passed

to another session, prematurely ending the second session's table or index scan. (Bug #56080, Bug

#11763382)

• In some cases, SHOW WARNINGS returned an empty result when the previous statement failed. (Bug

#55847, Bug #11763166)

• A handled condition (error or warning) could be shown as not handled at the end of the statement. (Bug

#55843, Bug #11763162)

References: This issue is a regression of: Bug #23032.

• In debug builds, Field_new_decimal::store_value() was subject to buffer overflows. (Bug

#55436, Bug #11762799)

• For an InnoDB table, dropping and adding an index in a single ALTER TABLE statement could fail. (Bug

#54927, Bug #11762345)

• For a client connected using SSL, the Ssl_cipher_list status variable was empty and did not show

the possible cipher types. (Bug #52596, Bug #11760210)

263

MySQL 5.6 Release Notes

• The mysql client sometimes did not properly close sessions terminated by the user with Control+C.

(Bug #52515, Bug #11760134)

• CREATE TABLE ... LIKE for a MyISAM table definition that included an DATA DIRECTORY or INDEX

DIRECTORY table option failed, instead of creating a table with those options omitted as documented.

(Bug #52354, Bug #11759990)

• Spatial operations on certain corner cases could cause a server crash: Polygons with zero-point

linerings; polygons with touching linerings. (Bug #51979, Bug #11759650, Bug #47429, Bug #11755628)

• Attempts to grant the EXECUTE or ALTER ROUTINE privilege for a nonexistent stored procedure

returned success instead of an error. (Bug #51401, Bug #11759114)

• With lower_case_table_names=2, resolution of objects qualified by database names could fail. (Bug

#50924, Bug #11758687)

• CREATE TABLE without an ENGINE option determined the default engine at parse rather than execution

time. This led to incorrect results if the statement was executed within a stored program and the default

engine had been changed in the meantime. (Bug #50614, Bug #11758414)

• On Linux, the mysql client built using the bundled libedit did not read ~/.editrc. (Bug #49967,

Bug #11757855)

• For some statements such as DESCRIBE or SHOW, views with too many columns produced errors. (Bug

#49437, Bug #11757397)

• The optimizer sometimes incorrectly processed HAVING clauses for queries that did not also have an

ORDER BY clause. (Bug #48916, Bug #11756928)

• PROCEDURE ANALYSE() could leak memory for NULL results, and could return incorrect results if used

with a LIMIT clause. (Bug #48137, Bug #11756242)

• A race condition between loading a stored routine using the name qualified by the database name

and dropping that database resulted in a spurious error message: The table mysql.proc is

missing, corrupt, or contains bad data (Bug #47870, Bug #11756013)

• When used to upgrade tables, mysqlcheck (and mysql_upgrade, which invokes mysqlcheck)

did not upgrade some tables for which table repair was found to be necessary. In particular, it failed

to upgrade InnoDB tables that needed repair, leaving them in a nonupgraded state. This occurred

because:

• mysqlcheck --check-upgrade ---auto-repair checks for tables that are incompatible

with the current version of MySQL. It does this by issuing the CHECK TABLE ... FOR UPGRADE

statement and examining the result.

• For any table found to be incompatible, mysqlcheck issues a REPAIR TABLE statement. But this

fails for storage engines such as InnoDB that do not support the repair operation. Consequently, the

table remained unchanged.

To fix the problem, the following changes were made to CHECK TABLE ... FOR UPGRADE and

mysqlcheck. Because mysql_upgrade invokes mysqlcheck, these changes also fix the problem for

mysql_upgrade.

• CHECK TABLE ... FOR UPGRADE returns a different error if a table needs repair but its storage

engine does not support REPAIR TABLE:

264

MySQL 5.6 Release Notes

Error: ER_TABLE_NEEDS_UPGRADE

Table upgrade required. Please do "REPAIR TABLE `tbl_name`" or

dump/reload to fix it!

Now:

Error: ER_TABLE_NEEDS_REBUILD

Table rebuild required. Please do "ALTER TABLE `tbl_name` FORCE" or

dump/reload to fix it!

• mysqlcheck recognizes the new error and issues an ALTER TABLE ... FORCE statement. The

FORCE option for ALTER TABLE was recognized but did nothing; now it is implemented and acts as a

“null” alter operation that rebuilds the table.

(Bug #47205, Bug #11755431)

• On some platforms, the Incorrect value: xxx for column yyy at row zzz error produced

by LOAD DATA could have an incorrect value of zzz. (Bug #46895, Bug #11755168)

• Upgrades using an RPM package recreated the test database, which is undesirable when the DBA had

removed it. (Bug #45415, Bug #11753896)

• In MySQL 5.1 and up, if a table had triggers that used syntax supported in 5.0 but not 5.1, the table

became unavailable. Now the table is marked as having broken triggers. These should be dropped and

recreated manually. (Bug #45235, Bug #11753738)

• An attempt to install nonexistent files during installation was corrected. (Bug #43247, Bug #11752142)

• Some status variables rolled over to zero after reaching the maximum 32-bit value. They have been

changed to 64-bit values. (Bug #42698, Bug #11751727)

• SHOW EVENTS did not always show events from the correct database. (Bug #41907, Bug #11751148)

• For queries with many eq_ref joins, the optimizer took excessive time to develop an execution plan.

(Bug #41740, Bug #11751026, Bug #58225, Bug #11765274)

• On FreeBSD 64-bit builds of the embedded server, exceptions were not prevented from propagating into

the embedded application. (Bug #38965, Bug #11749418)

• With DISTINCT, CONCAT(col_name,...) returned incorrect results when the arguments to

CONCAT() were columns with an integer data type declared with a display width narrower than the

values in the column. (For example, if an INT(1) column contained 1111.) (Bug #4082)

Changes in MySQL 5.6.2 (2011-04-11, Developer Milestone)

Note

This is a milestone release, for use at your own risk. Upgrades between milestone

releases (or from a milestone release to a GA release) are not supported.

Significant development changes take place in milestone releases and you may

encounter compatibility issues, such as data format changes that require attention

in addition to the usual procedure of running mysql_upgrade. For example, you

may find it necessary to dump your data with mysqldump before the upgrade and

reload it afterward. (Making a backup before the upgrade is a prudent precaution in

any case.)

• INFORMATION_SCHEMA Tables for InnoDB Buffer Pool Information

265

MySQL 5.6 Release Notes

• INFORMATION_SCHEMA Table for InnoDB Metrics

• INFORMATION_SCHEMA Tables for InnoDB Data Dictionary

• Persistent InnoDB Optimizer Statistics

• InnoDB Configurable Data Dictionary Cache

• Optimizer Notes

• Explicit Partition Selection

• Performance Schema Notes

• Pluggable Authentication

• Plugin Notes

• Crash-Safe Binary Log

• Slave Log Tables

• Row Image Control

• Functionality Added or Changed

• Bugs Fixed

INFORMATION_SCHEMA Tables for InnoDB Buffer Pool Information

• InnoDB: The new INFORMATION_SCHEMA tables INNODB_BUFFER_PAGE,

INNODB_BUFFER_PAGE_LRU, and INNODB_BUFFER_POOL_STATS display InnoDB buffer pool

information for tuning on large-memory or highly loaded systems. (WL #5614)

INFORMATION_SCHEMA Table for InnoDB Metrics

• InnoDB: A new INFORMATION_SCHEMA table, INNODB_METRICS, lets you query low-level InnoDB

performance information, getting cumulative counts, averages, and minimum/maximum values for

internal aspects of the storage engine operation. You can start, stop, and reset the metrics counters

using the innodb_monitor_enable, innodb_monitor_disable, innodb_monitor_reset, and

innodb_monitor_reset_all system variables. (WL #5316, WL #5776)

INFORMATION_SCHEMA Tables for InnoDB Data Dictionary

• InnoDB: The InnoDB data dictionary, containing metadata about InnoDB tables, columns, indexes, and

foreign keys, is available for SQL queries through a set of INFORMATION_SCHEMA tables. (WL #5373)

Persistent InnoDB Optimizer Statistics

• Performance; InnoDB: The optimizer statistics for InnoDB tables can now persist across server

restarts, producing more stable query performance. You can also control the amount of sampling

done to estimate cardinality for each index, resulting in more accurate optimizer statistics. This

feature involves the configuration options innodb_analyze_is_persistent (later replaced

by innodb_stats_persistent), innodb_stats_persistent_sample_pages, and

innodb_stats_transient_sample_pages, and the ANALYZE TABLE statement. See Configuring

Persistent Optimizer Statistics Parameters for details. (WL #5520)

266

MySQL 5.6 Release Notes

InnoDB Configurable Data Dictionary Cache

• InnoDB: To ease the memory load on systems with huge numbers of tables, InnoDB now frees up

the memory associated with an opened table using an LRU algorithm to select tables that have gone

the longest without being accessed. To reserve more memory to hold metadata for open InnoDB

tables, increase the value of the table_definition_cache configuration option. InnoDB treats

this value as a “soft limit” for the number of open table instances in the InnoDB data dictionary

cache. The actual number of tables with cached metadata could be higher than the value specified

for table_definition_cache, because metadata for InnoDB system tables, and parent and child

tables in foreign key relationships, is never evicted from memory. For additional information, refer to the

table_definition_cache documentation. (Bug #20877, Bug #11745884, WL #5457)

Optimizer Notes

• The optimizer now more efficiently handles queries (and subqueries) of the following form:

SELECT ...

FROM single_table ...

ORDER BY non_index_column [DESC]

LIMIT [M,]N;

That type of query is common in web applications that display only a few rows from a larger result set.

For example:

SELECT col1, ... FROM t1 ... ORDER BY name LIMIT 10;

SELECT col1, ... FROM t1 ... ORDER BY RAND() LIMIT 15;

The sort buffer has a size of sort_buffer_size. If the sort elements for N rows are small enough to fit

in the sort buffer (M+N rows if M was specified), the server can avoid using a merge file and perform the

sort entirely in memory. For details, see LIMIT Query Optimization. (WL #1393)

• The optimizer implements Disk-Sweep Multi-Range Read. Reading rows using a range scan on a

secondary index can result in many random disk accesses to the base table when the table is large and

not stored in the storage engine's cache. With the Disk-Sweep Multi-Range Read (MRR) optimization,

MySQL tries to reduce the number of random disk access for range scans by first scanning the index

only and collecting the keys for the relevant rows. Then the keys are sorted and finally the rows are

retrieved from the base table using the order of the primary key. The motivation for Disk-sweep MRR is

to reduce the number of random disk accesses and instead achieve a more sequential scan of the base

table data. For more information, see Multi-Range Read Optimization. (WL #5692)

• The optimizer implements Index Condition Pushdown (ICP), an optimization for the case where MySQL

retrieves rows from a table using an index. Without ICP, the storage engine traverses the index to locate

rows in the base table and returns them to the MySQL server which evaluates the WHERE condition for

the rows. With ICP enabled, and if parts of the WHERE condition can be evaluated by using only fields

from the index, the MySQL server pushes this part of the WHERE condition down to the storage engine.

The storage engine then evaluates the pushed index condition by using the index entry and only if this

is satisfied is base row be read. ICP can reduce the number of accesses the storage engine has to do

against the base table and the number of accesses the MySQL server has to do against the storage

engine. For more information, see Index Condition Pushdown Optimization. (WL #5639)

Explicit Partition Selection

• Partitioning: It is now possible to select one or more partitions or subpartitions when querying a

partitioned table. In addition, many data modification statements (DELETE, INSERT, REPLACE, UPDATE,

LOAD DATA, and LOAD XML) that act on partitioned tables also now support explicit partition selection.

For example, assume we have a table named t with some integer column named c, and t has 4

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MySQL 5.6 Release Notes

partitions named p0, p1, p2, and p3. Then the query SELECT * FROM t PARTITION (p0, p1)

WHERE c < 5 returns rows only in partitions p0 and p1 that match the WHERE condition, whereas

partitions p2 and p3 are not checked.

For additional information and examples, see Partition Selection, as well as the descriptions of the

statements just listed. (WL #5217)

Performance Schema Notes

• The Performance Schema has these additions:

• The Performance Schema now has tables that contain summaries for table and index I/O wait events,

as generated by the wait/io/table/sql/handler instrument:

• table_io_waits_summary_by_table: Aggregates table I/O wait events. The grouping is by

table.

• table_io_waits_summary_by_index_usage: Aggregates table index I/O wait events. The

grouping is by table index.

The information in these tables can be used to assess the impact of table I/O performed by

applications. For example, it is possible to see which tables are used and which indexes are used (or

not used), or to identify bottlenecks on a table when multiple applications access it. The results may be

useful to change how applications issue queries against a database, to minimize application footprint

on the server and to improve application performance and scalability.

A change that accompanies the new tables is that the events_waits_current table now

has an INDEX_NAME column to identify which index was used for the operation that generated

the event. The same is true of the event-history tables, events_waits_history, and

events_waits_history_long.

• The Performance Schema now has an instrument named wait/lock/table/sql/handler in the

setup_instruments table for instrumenting table lock wait events. It differs from wait/io/table/

sql/handler, which instruments table I/O. This enables independent instrumentation of table I/O

and table locks.

Accompanying the new instrument, the Performance Schema has a table named

table_lock_waits_summary_by_table that aggregates table lock wait events, as generated by

the new instrument. The grouping is by table.

The information in this table may be used to assess the impact of table locking performed by

applications. The results may be useful to change how applications issue queries against the database

and use table locks, to minimize the application footprint on the server and to improve application

performance and scalability. For example, an application locking tables for a long time may negatively

affect other applications; the instrumentation makes this visible.

• To selectively control which tables to instrument for I/O and locking, use the setup_objects table.

See Pre-Filtering by Object.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the performance_schema database.

For more information, see MySQL Performance Schema. (WL #5379, WL #5420, WL #5371)

268

MySQL 5.6 Release Notes

Pluggable Authentication

• MySQL distributions now include auth_socket, a server-side authentication plugin that authenticates

clients that connect from the local host through the Unix socket file. The plugin uses the SO_PEERCRED

socket option to obtain information about the user running the client program (and thus can be built

only on systems that support this option). For a connection to succeed, the plugin requires a match

between the login name of the connecting client user and the MySQL user name presented by the client

program. For more information, see Socket Peer-Credential Pluggable Authentication. (Bug #59017, Bug

#11765993, Bug #9411, Bug #11745104)

• MySQL distributions now include mysql_clear_password, a client-side authentication plugin that

sends the password to the server without hashing or encryption. Although this is insecure, and thus

appropriate precautions should be taken (such as using an SSL connection), the plugin is useful in

conjunction with server-side plugins that must have access to the original password in clear text. For

more information, see Client-Side Cleartext Pluggable Authentication.

Plugin Notes

• A new plugin service, my_plugin_log_service, enables plugins to report errors and specify error

messages. The server writes the messages to the error log. See MySQL Plugin Services. (WL #2940)

Crash-Safe Binary Log

• Replication: Support for checksums when writing and reading the binary log is added to the MySQL

Server. Writing checksums into the binary log is disabled by default; it can be enabled by starting the

server with the --binlog-checksum option. To cause the server to read checksums from the binary

log, start the server with the master_verify_checksum system variable enabled. The --slave-

sql-verify-checksum option causes the slave to read checksums from the relay log. (WL #2540)

• Replication: The MySQL Server now records and reads back only complete events or transactions to

and from the binary log. By default, the server now logs the length of the event as well as the event itself

and uses this information to verify that the event was written correctly to the log. A master also uses by

default this value to verify events when reading from the binary log.

If you enable writing of checksums (using the binlog_checksum system variable), the master can

use these instead by enabling the master_verify_checksum system variable. The slave I/O thread

also verifies events received from the master. You can cause the slave SQL thread to use checksums

(if available) as well, when reading from the relay log, by enabling the slave_sql_verify_checksum

system variable on the slave. (WL #5493, WL #2540)

Slave Log Tables

• Replication: It is now possible to write information about the slave connection to the master

and about the slave's execution point within the relay log to tables rather than files. Logging

of master connection information and of slave relay log information to tables can be done

independently of one another; this is controlled by the master_info_repository and

relay_log_info_repository system variables. When master_info_repository=TABLE,

connection information is logged in the slave_master_info table in the mysql system

database. When relay_log_info_repository=TABLE, relay log information is logged to the

slave_relay_log_info table, also in the mysql system database. (WL #2775, WL #5125)

Row Image Control

• Replication: Added the binlog_row_image server system variable, which can be used to enable row

image control for row-based replication. This means that you can potentially save disk space, network

269

MySQL 5.6 Release Notes

resources, and memory usage by the MySQL Server by logging only those columns that are required for

uniquely identifying rows, or which are actually changed on each row, as opposed to logging all columns

for each and every row change event. In addition, you can use a “noblob” mode where all columns,

except for unneeded BLOB or TEXT columns, are logged.

For more information, see System Variables Used with Binary Logging. (Bug #47200, Bug #47303, Bug

#56917, Bug #11755426, Bug #11755513, Bug #11764116, WL #5092)

Functionality Added or Changed

• Incompatible Change: The following obsolete constructs have been removed. Where alternatives are

shown, applications should be updated to use them.

• The FLUSH MASTER and FLUSH SLAVE statements. Use the RESET MASTER and RESET SLAVE

statements instead.

(WL #5185, WL #6311)

• Important Change; Replication: Added the binlog_rows_query_log_events system variable

for mysqld. Enabling this variable causes a server logging in row-based mode to write informational

rows query log events (SQL statements, for debugging and other purposes) to the binary log. MySQL

server and MySQL programs from MySQL 5.6.2 and later normally ignore such events, so that they

do not pose an issue when reading the binary log. mysqld and mysqlbinlog from previous MySQL

releases cannot read such events in the binary log, and fail if they attempt to do so. For this reason, you

should never prepare logs for a MySQL 5.6.1 or earlier replication slave server (or other reader such as

mysqlbinlog) with this option enabled on the master. (Bug #50935, Bug #11758695, WL #4033, WL

#5404)

• Performance; InnoDB: A separate InnoDB thread (page_cleaner) now handles the flushing of dirty

pages that was formerly done by the InnoDB master thread. (Bug #11762412, Bug #55004, WL #5579)

• Performance; InnoDB: The innodb_purge_threads system variable can now be set to a value

higher than 1. (WL #5459)

• Performance; InnoDB: The InnoDB kernel mutex, which controls concurrent access to the InnoDB

kernel, has been split into several mutexes and rw-locks, for improved concurrency. (WL #5458)

• InnoDB: InnoDB can optionally log details about all deadlocks that occur, to assist with troubleshooting

and diagnosis. This feature is controlled by the innodb_print_all_deadlocks system variable. (Bug

#1784, Bug #17572, WL #5674)

• Replication: On MySQL replication slaves having multiple network interfaces, it is now possible to set

which interface to use for connecting to the master using the MASTER_BIND='interface' option in a

CHANGE MASTER TO statement.

The value set by this option can be seen in the Master_Bind column of the output from SHOW SLAVE

STATUS or the Bind column of the mysql.slave_master_info table. (Bug #25939, Bug #11746389,

WL #3127)

• Replication: Added the log_bin_basename system variable, which contains the complete file name

and path to the binary log file. (The log_bin system variable shows only whether or not binary logging

is enabled; log_bin_basename, however, reflects the name set with the --log-bin server option.)

Also added relay_log_basename system variable, which shows the file name and complete path to

the relay log file. (WL #5465)

References: See also: Bug #19614, Bug #11745759.

270

MySQL 5.6 Release Notes

• The mysql_upgrade, mysqlbinlog, mysqlcheck, mysqlimport, mysqlshow, and mysqlslap

clients now have --default-auth and --plugin-dir options for specifying which authentication

plugin and plugin directory to use. (Bug #58139)

• The server now includes the thread ID in rows written to the slow query log. In the slow query log file,

the thread ID is the last value in the line. In the mysql.slow_log log table, there is a new thread_id

column.

To update the slow_log table if you are upgrading from an earlier release, run mysql_upgrade

and restart the server. See mysql_upgrade — Check and Upgrade MySQL Tables. (Bug #53630, Bug

#11761166)

• The server now writes thread shutdown messages to the error log during the shutdown procedure. (Bug

#48388, Bug #11756464)

• If the init_file system variable is given, the server now writes messages indicating the beginning and

end of file execution to the error log. (Bug #48387, Bug #11756463)

• Boolean system variables can be enabled at run time by setting them to the value ON or OFF, but

previously this did not work at server startup. Now at startup such variables can be enabled by setting

them to ON or TRUE, or disabled by setting them to OFF or FALSE. Any other nonnumeric value is invalid.

(Bug #46393)

References: See also: Bug #11754743, Bug #51631.

• MySQL distributions now include an INFO_SRC file that contains information about the source

distribution, such as the MySQL version from which it was created. MySQL binary distributions

additionally include an INFO_BIN file that contains information about how the distribution was built, such

as compiler options and feature flags. In RPM packages, these files are located in the /usr/share/

doc/packages/MySQL-server directory. In tar.gz and derived packages, they are located in the

Docs directory under the location where the distribution is unpacked. (Bug #42969, Bug #11751935)

• Multi-read range access is now based on cost estimates and no longer used for simple queries for which

it is not beneficial. (Bug #37576, Bug #11748865)

• Previously, for queries that were aborted due to a sort problem, the server wrote the message Sort

aborted to the error log. Now the server writes more information to provide a more specific message,

such as:

Sort aborted: Out of memory (Needed 24 bytes)

Out of sort memory, consider increasing server sort buffer size

Sort aborted: Out of sort memory, consider increasing server sort

buffer size

Sort aborted: Incorrect number of arguments for FUNCTION test.f1;

expected 0, got 1

In addition, if the server was started with --log-warnings=2, the server writes information about the

host, user, and query. (Bug #36022, Bug #11748358)

• Previously, for queries that were aborted due to a sort problem or terminated with KILL in the middle

of a sort, the server wrote the message Sort aborted to the error log. Now the server writes more

information about the cause of the error. These causes include:

• Insufficient disk space in the temporary file directory prevented a temp file from being created

• Insufficient memory for sort_buffer_size to be allocated

• Somebody ran KILL id in the middle of a filesort operation

271

MySQL 5.6 Release Notes

• The server was shut down while some queries were sorting

• A transaction was rolled back or aborted due to a lock wait timeout or deadlock

• Unexpected errors, such as a source table or even temp table was corrupt

• Processing of a subquery failed which was also sorting

(Bug #30771, Bug #11747102)

• mysqldump --xml now displays comments from column definitions. (Bug #13618, Bug #11745324)

• Windows provides APIs based on UTF-16LE for reading from and writing to the console. MySQL now

supports a utf16le character set for UTF-16LE, and the mysql client for Windows has been modified

to provide improved Unicode support by using these APIs.

To take advantage of this change, you must run mysql within a console that uses a compatible Unicode

font and set the default character set to a Unicode character set that is supported for communication with

the server. For instructions, see Unicode Support on Windows. (WL #5331)

• The undocumented SHOW NEW MASTER statement has been removed, and the

Com_show_new_master status variable along with it. (WL #5670)

Bugs Fixed

• Security Fix: Pre-evaluation of LIKE predicates during view preparation could cause a server crash.

(Bug #54568, Bug #11762026)

• Incompatible Change; Replication: It is no longer possible to issue a CREATE TABLE ... SELECT

statement which changes any tables other than the table being created. Any such statement is not

executed and instead fails with an error.

One consequence of this change is that FOR UPDATE may no longer be used at all with the SELECT

portion of a CREATE TABLE ... SELECT.

This means that, prior to upgrading from a previous release, you should rewrite any CREATE

TABLE ... SELECT statements that cause changes in other tables so that the statements no longer do

so.

This change also has implications for replication between a MySQL 5.6 (or later slave) and a master

running a previous version of MySQL. In such a case, if a CREATE TABLE ... SELECT statement on

the master that causes changes in other tables succeeds on the master, the statement nonetheless fails

on the slave, causing replication to stop. To keep this from happening, you should rewrite the offending

statement before running it on the master. (Bug #11749792, Bug #11745361, Bug #39804, Bug #55876,

WL #5576)

References: See also: Bug #47899.

• Incompatible Change: When auto_increment_increment is greater than one, values generated by

a bulk insert that reaches the maximum column value could wrap around rather producing an overflow

error.

As a consequence of the fix, it is no longer possible for an auto-generated value to be equal to the

maximum BIGINT UNSIGNED value. It is still possible to store that value manually, if the column can

accept it. (Bug #39828, Bug #11749800)

272

MySQL 5.6 Release Notes

• Important Change; Partitioning: Date and time functions used as partitioning functions now have the

types of their operands checked; use of a value of the wrong type is now disallowed in such cases. In

addition, EXTRACT(WEEK FROM col_name), where col_name is a DATE or DATETIME column, is now

disallowed altogether because its return value depends on the value of the default_week_format

system variable. (Bug #54483, Bug #11761948)

References: See also: Bug #57071, Bug #11764255.

• Important Change; Replication: The CHANGE MASTER TO statement required the value for

RELAY_LOG_FILE to be an absolute path, whereas the MASTER_LOG_FILE path could be relative.

The inconsistent behavior is resolved by permitting relative paths for RELAY_LOG_FILE, in which case

the path is assumed to be relative to the slave's data directory. (Bug #12190, Bug #11745232)

• Performance; InnoDB: An UPDATE statement for an InnoDB table could be slower than necessary if it

changed a column covered by a prefix index, but did not change the prefix portion of the value. The fix

improves performance for InnoDB 1.1 in MySQL 5.5 and higher, and the InnoDB Plugin for MySQL 5.1.

(Bug #58912, Bug #11765900)

• InnoDB; Partitioning: The partitioning handler did not pass locking information to a table's storage

engine handler. This caused high contention and thus slower performance when working with partitioned

InnoDB tables. (Bug #59013)

• InnoDB: This fix introduces a new configuration option, innodb_change_buffer_max_size, which

defines the size of the change buffer as a percentage of the size of the buffer pool. Because the change

buffer shares memory space with the buffer pool, a workload with a high rate of DML operations could

cause pages accessed by queries to age out of the buffer pool sooner than desirable. This fix also

devotes more I/O capacity to flushing entries from the change buffer when it exceeds 1/2 of its maximum

size. (Bug #11766168, Bug #59214)

• InnoDB: The presence of a double quotation mark inside the COMMENT field for a column could prevent

a foreign key constraint from being created properly. (Bug #59197, Bug #11766154)

• InnoDB: It was not possible to query the information_schema.INNODB_TRX table while other

connections were running queries involving BLOB types. (Bug #55397, Bug #11762763)

• InnoDB: InnoDB returned values for “rows examined” in the query plan that were higher than expected.

NULL values were treated in an inconsistent way. The inaccurate statistics could trigger “false positives”

in combination with the max_join_size setting, because the queries did not really examine as many

rows as reported.

A new configuration option innodb_stats_method lets you specify how NULL values are treated

when calculating index statistics. Allowed values are nulls_equal (the default), nulls_unequal and

null_ignored. The meanings of these values are similar to those of the myisam_stats_method

option. (Bug #30423)

• Partitioning: Failed ALTER TABLE ... PARTITION statements could cause memory leaks. (Bug

#56380, Bug #11763641)

References: See also: Bug #46949, Bug #11755209, Bug #56996, Bug #11764187.

• Replication: When using the statement-based logging format, INSERT ON DUPLICATE KEY UPDATE

and INSERT IGNORE statements affecting transactional tables that did not fail were not written to the

binary log if they did not insert any rows. (With statement-based logging, all successful statements

should be logged, whether they do or do not cause any rows to be changed.) (Bug #59338, Bug

#11766266)

273

MySQL 5.6 Release Notes

• Replication: Formerly, STOP SLAVE stopped the slave I/O thread first and then stopped the slave SQL

thread; thus, it was possible for the I/O thread to stop after replicating only part of a transaction which the

SQL thread was executing, in which case—if the transaction could not be rolled back safely—the SQL

thread could hang.

Now, STOP SLAVE stops the slave SQL thread first and then stops the I/O thread; this guarantees

that the I/O thread can fetch any remaining events in the transaction that the SQL thread is executing,

so that the SQL thread can finish the transaction if it cannot be rolled back safely. (Bug #58546, Bug

#11765563)

• Replication: mysqlbinlog printed USE statements to its output only when the default database

changed between events. To illustrate how this could cause problems, suppose that a user issued the

following sequence of statements:

CREATE DATABASE mydb;

USE mydb;

CREATE TABLE mytable (column_definitions);

DROP DATABASE mydb;

CREATE DATABASE mydb;

USE mydb;

CREATE TABLE mytable (column_definitions);

When played back using mysqlbinlog, the second CREATE TABLE statement failed with Error: No

Database Selected because the second USE statement was not played back, due to the fact that a

database other than mydb was never selected.

This fix ensures that mysqlbinlog outputs a USE statement whenever it reads one from the binary log.

(Bug #50914, Bug #11758677)

• Replication: The --help text for mysqlbinlog now indicates that the --verbose (-v) option outputs

pseudo-SQL that is not necessarily valid SQL and cannot be guaranteed to work verbatim in MySQL

clients. (Bug #47557, Bug #11755743)

• Microsoft Windows: On Windows, an object in thread local storage could be used before the object

was created. (Bug #55730, Bug #11763065)

• Two unused test files in storage/ndb/test/sql contained incorrect versions of the GNU Lesser

General Public License. The files and the directory containing them have been removed. (Bug

#11810224)

References: See also: Bug #11810156.

• Queries that used COALESCE() with cp1251 strings could result in an “illegal mix of collations” error.

(Bug #60101, Bug #11766874)

• An assertion was raised if an XA COMMIT was issued when an XA transaction had already encountered

an error (such as a deadlock) that required the transaction to be rolled back. (Bug #59986, Bug

#11766788)

• On some systems, debug builds of comp_err could fail due to an uninitialized variable. (Bug #59906,

Bug #11766729)

• Setting the optimizer_switch system variable to an invalid value caused a server crash. (Bug

#59894, Bug #11766719)

• Attempting to create a spatial index on a CHAR column longer than 31 bytes led to an assertion failure if

the server was compiled with safemutex support. (Bug #59888, Bug #11766714)

• Aggregation followed by a subquery could produce an incorrect result. (Bug #59839, Bug #11766675)

274

MySQL 5.6 Release Notes

• The Performance Schema did not update status handler status variables, so SHOW STATUS LIKE

'%handler%' produced undercounted values. (Bug #59799, Bug #11766645)

• Internally, XOR items partially behaved like functions and partially as conditions. This resulted in

inconsistent handling and crashes. The issue is fixed by consistently treating XOR items as functions.

(Bug #59793, Bug #11766642)

• An incorrect character set pointer passed to my_strtoll10_mb2() caused an assertion to be raised.

(Bug #59648, Bug #11766519)

• DES_DECRYPT() could crash if the argument was not produced by DES_ENCRYPT(). (Bug #59632, Bug

#11766505)

• The server and client did not always properly negotiate authentication plugin names. (Bug #59453, Bug

#11766356)

• --autocommit=ON did not work (it set the global autocommit value to 0, not 1). (Bug #59432, Bug

#11766339)

• FIND_IN_SET() could work differently in MySQL 5.5 than in 5.1. (Bug #59405, Bug #11766317)

• mysqldump did not quote database names in ALTER DATABASE statements in its output, which could

cause an error at reload time for database names containing a dash. (Bug #59398, Bug #11766310)

• If filesort fell back to an ordinary sort/merge, it could fail to handle memory correctly. (Bug #59331,

Bug #11766260)

• Comparisons of aggregate values with TIMESTAMP values were incorrect. (Bug #59330, Bug

#11766259)

• The “greedy” query plan optimizer failed to consider the size of intermediate query results when

calculating the cost of a query. This could result in slowly executing queries when there are much faster

execution plans available. (Bug #59326, Bug #11766256)

• A query of the following form returned an incorrect result, where the values for col_name in the result

set were entirely replaced with NULL values:

SELECT DISTINCT col_name ... ORDER BY col_name DESC;

(Bug #59308, Bug #11766241)

• The MYSQL_HOME environment variable was being ignored. (Bug #59280, Bug #11766219)

• SHOW PRIVILEGES did not display a row for the PROXY privilege. (Bug #59275, Bug #11766216)

• SHOW PROFILE could truncate source file names or fail to show function names. (Bug #59273, Bug

#11766214)

• For DIV expressions, assignment of the result to multiple variables could cause a server crash. (Bug

#59241, Bug #11766191)

References: See also: Bug #8457.

• MIN(year_col) could return an incorrect result in some cases. (Bug #59211, Bug #11766165)

• With index condition pushdown enabled, a join could produce an extra row due to parts of the select

condition for the second table in the join not being evaluated. (Bug #59186, Bug #11766144)

• DELETE or UPDATE statements could fail if they used DATE or DATETIME values with a year, month, or

day part of zero. (Bug #59173)

275

MySQL 5.6 Release Notes

• The ESCAPE clause for the LIKE operator permits only expressions that evaluate to a constant at

execution time, but aggregate functions were not being rejected. (Bug #59149, Bug #11766110)

• Valgrind warnings about uninitialized variables were corrected. (Bug #59145, Bug #11766106)

• Memory leaks detected by Valgrind, some of which could cause incorrect query results, were corrected.

(Bug #59110, Bug #11766075)

• mysqlslap failed to check for a NULL return from mysql_store_result() and crashed trying to

process the result set. (Bug #59109, Bug #11766074)

• There was an erroneous restriction on file attributes for LOAD DATA. The requirement that a file be

located in the database directory or world readable is now that the be located in the database directory

or readable by the user account used to run the server. (Bug #59085, Bug #11766052)

• SHOW CREATE TRIGGER failed if there was a temporary table with the same name as the trigger subject

table. (Bug #58996, Bug #11765972)

• The DEFAULT_CHARSET and DEFAULT_COLLATION CMake options did not work. (Bug #58991, Bug

#11765967)

• In a subquery, a UNION with no referenced tables (or only a reference to the DUAL virtual table) did not

permit an ORDER BY clause. (Bug #58970, Bug #11765950)

• OPTIMIZE TABLE for an InnoDB table could raise an assertion if the operation failed because it had

been killed. (Bug #58933, Bug #11765920)

• If max_allowed_packet was set larger than 16MB, the server failed to reject too-large packets with

“Packet too large” errors. (Bug #58887, Bug #11765878)

• With index condition pushdown enabled, incorrect results were returned for queries on MyISAM tables

involving HAVING and LIMIT, when the column in the WHERE condition contained NULL. (Bug #58838,

Bug #11765835)

• An uninitialized variable for the index condition pushdown access method could result in a server crash

or Valgrind warnings. (Bug #58837, Bug #11765834)

• A NOT IN predicate with a subquery containing a HAVING clause could retrieve too many rows, when

the subquery itself returned NULL. (Bug #58818, Bug #11765815)

• Running a query against an InnoDB table twice, first with index condition pushdown enabled and then

with it disabled, could produce different results. (Bug #58816, Bug #11765813)

• An assertion was raised if a stored routine had a DELETE IGNORE statement that failed but due to the

IGNORE had not reported any error. (Bug #58709, Bug #11765717)

• WHERE conditions of the following forms were evaluated incorrectly and could return incorrect results:

WHERE null-valued-const-expression NOT IN (subquery)

WHERE null-valued-const-expression IN (subquery) IS UNKNOWN

(Bug #58628, Bug #11765642)

• Issuing EXPLAIN EXTENDED for a query that would use condition pushdown could cause mysqld to

crash. (Bug #58553, Bug #11765570)

• An OUTER JOIN query using WHERE col_name IS NULL could return an incorrect result. (Bug

#58490, Bug #11765513)

276

MySQL 5.6 Release Notes

• Starting the server with the --defaults-file=file_name option, where the file name had no

extension, caused a server crash. (Bug #58455, Bug #11765482)

• Outer joins with an empty table could produce incorrect results. (Bug #58422, Bug #11765451)

• In debug builds, SUBSTRING_INDEX(FORMAT(...), FORMAT(...)) could cause a server crash.

(Bug #58371, Bug #11765406)

• When mysqladmin was run with the --sleep and --count options, it went into an infinite loop

executing the specified command. (Bug #58221, Bug #11765270)

• Some string-manipulating SQL functions use a shared string object intended to contain an immutable

empty string. This object was used by the SQL function SUBSTRING_INDEX() to return an empty

string when one argument was of the wrong data type. If the string object was then modified by the SQL

function INSERT(), undefined behavior ensued. (Bug #58165, Bug #11765225)

• Condition pushdown optimization could push down conditions with incorrect column references. (Bug

#58134, Bug #11765196)

• injector::transaction did not have support for rollback. (Bug #58082, Bug #11765150)

• Parsing nested regular expressions could lead to recursion resulting in a stack overflow crash. (Bug

#58026, Bug #11765099)

• The fix for Bug #25192 caused load_defaults() to add an argument separator to distinguish options

loaded from option files from those provided on the command line, whether or not the application needed

it. (Bug #57953, Bug #11765041)

References: See also: Bug #25192, Bug #11746296.

• The mysql client went into an infinite loop if the standard input was a directory. (Bug #57450, Bug

#11764598)

• If a multiple-table update updated a row through two aliases and the first update physically moved

the row, the second update failed to locate the row. This resulted in different errors depending on the

storage engine, although these errors did not accurately describe the problem:

• MyISAM: Got error 134 from storage engine

• InnoDB: Can't find record in 'tbl'

For MyISAM, which is nontransactional, the update executed first was performed but the second was

not. In addition, for two equal multiple-table update statements, one could succeed and the other fail

depending on whether the record actually moved, which is inconsistent.

Now such an update returns an error if it will update a table through multiple aliases, and perform an

update that may physically move the row in at least one of these aliases. (Bug #57373, Bug #11764529,

Bug #55385, Bug #11762751)

• SHOW WARNINGS output following EXPLAIN EXTENDED could include unprintable characters. (Bug

#57341, Bug #11764503)

• Outer joins on a unique key could return incorrect results. (Bug #57034, Bug #11764219)

• For a query that used a subquery that included GROUP BY inside a < ANY() construct, no rows were

returned when there should have been. (Bug #56690, Bug #11763918)

277

MySQL 5.6 Release Notes

• Some RPM installation scripts used a hardcoded value for the data directory, which could result in a

failed installation for users who have a nonstandard data directory location. The same was true for other

configuration values such as the PID file name. (Bug #56581, Bug #11763817)

• On FreeBSD and OpenBSD, the server incorrectly checked the range of the system date, causing legal

values to be rejected. (Bug #55755, Bug #11763089)

• If one connection locked the mysql.func table using either FLUSH TABLES WITH READ LOCK or

LOCK TABLE mysql.func WRITE and a second connection tried to either create or drop a loadable

function, a deadlock occurred when the first connection tried to use a loadable function. (Bug #53322,

Bug #11760878)

• DISTINCT aggregates on DECIMAL UNSIGNED fields could trigger an assertion. (Bug #52171, Bug

#11759827)

• On FreeBSD, if mysqld was killed with a SIGHUP signal, it could corrupt InnoDB .ibd files. (Bug

#51023, Bug #11758773)

•

An assertion could be raised if −1 was inserted into an AUTO_INCREMENT column by a statement writing

more than one row. (Bug #50619, Bug #11758417)

• A query that contains an aggregate function but no GROUP BY clause is implicitly grouped. If such a

query also contained an ORDER BY clause, the optimizer could choose to use a temporary table to

perform the ordering. This is unnecessary because implicitly grouped queries return at most one row and

need no ordering. (Bug #47853)

• The parser failed to initialize some internal objects properly, which could cause a server crash in the

cleanup phase after statement execution. (Bug #47511, Bug #11755703)

• When CASE ... WHEN arguments had different character sets, 8-bit values could be referenced as

utf16 or utf32 values, raising an assertion. (Bug #44793, Bug #11753363)

• When using ExtractValue() or UpdateXML(), if the XML to be read contained an incomplete XML

comment, MySQL read beyond the end of the XML string when processing, leading to a crash of the

server. (Bug #44332, Bug #11752979)

• Bitmap functions used in one thread could change bitmaps used by other threads, raising an assertion.

(Bug #43152, Bug #11752069)

• DATE_ADD() and DATE_SUB() return a string if the first argument is a string, but incorrectly returned

a binary string. Now they return a character string with a collation of connection_collation. (Bug

#31384, Bug #11747221)

Changes in MySQL 5.6.1 (Not released, Milestone 5)

Note

This is a milestone release, for use at your own risk. Upgrades between milestone

releases (or from a milestone release to a GA release) are not supported.

Significant development changes take place in milestone releases and you may

encounter compatibility issues, such as data format changes that require attention

in addition to the usual procedure of running mysql_upgrade. For example, you

may find it necessary to dump your data with mysqldump before the upgrade and

reload it afterward. (Making a backup before the upgrade is a prudent precaution in

any case.)

278

MySQL 5.6 Release Notes

• Performance Schema Notes

• Functionality Added or Changed

• Bugs Fixed

Performance Schema Notes

• The Performance Schema has these additions:

• The setup_consumers table contents have changed. Previously, the table used a “flat” structure

with a one-to-one correspondence between consumer name and destination table. This has been

replaced with a hierarchy of consumer settings that enable progressively finer control of which

destinations receive events. The previous xxx_summary_xxx consumers no longer exist. Instead,

the Performance Schema maintains appropriate summaries automatically for the levels for which

settings in the consumer hierarchy are enabled. For example, if only the top-level (global) consumer

is enabled, only global summaries are maintained. Others, such as thread-level summaries, are not.

See Pre-Filtering by Consumer. In addition, optimizations have been added to reduce Performance

Schema overhead.

• It is now possible to filter events by object using the new setup_objects table. Currently, this table

can be used to selectively instrument tables, based on schema names and/or table names. See Pre-

Filtering by Object. A new table, objects_summary_global_by_type, summarizes events for

objects.

• It is now possible to filter events by thread, and the Performance Schema collects more information

for each thread. A new table, setup_actors, can be used to selectively instrument user

connections, based on the user name and/or host name of each connecting session. The

threads table, which contains a row for each active server thread, was extended with several new

columns. With these additions, the information available in threads is like that available from the

INFORMATION_SCHEMA.PROCESSLIST table or the output from SHOW PROCESSLIST. Thus, all three

serve to provide information for thread-monitoring purposes. Use of threads differs from use of the

other two thread information sources in these ways:

• Access to threads does not require a mutex and has minimal impact on server performance.

INFORMATION_SCHEMA.PROCESSLIST and SHOW PROCESSLIST have negative performance

consequences because they require a mutex.

• threads provides additional information for each thread, such as whether it is a foreground or

background thread, and the location within the server associated with the thread.

• threads provides information about background threads. This means that threads can be used to

monitor activity the other thread information sources cannot.

• You can control which threads are monitored by setting the INSTRUMENTED column or by using the

setup_actors table.

For these reasons, DBAs who perform server monitoring using

INFORMATION_SCHEMA.PROCESSLIST or SHOW PROCESSLIST may wish to monitor using threads

instead.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the performance_schema database.

For more information, see MySQL Performance Schema. (WL #4674, WL #4816)

279

MySQL 5.6 Release Notes

Functionality Added or Changed

• Incompatible Change: The following obsolete constructs have been removed. Where alternatives are

shown, applications should be updated to use them.

• The --log server option and the log system variable. Instead, use the general_log system

variable to enable the general query log and the general_log_file system variable to set the

general query log file name.

• The log_slow_queries system variable. Instead, use the slow_query_log system variable to

enable the slow query log and the slow_query_log_file system variable to set the slow query log

file name.

• The --one-thread server option. Use --thread_handling=no-threads instead.

• The --skip-thread-priority server option.

• The engine_condition_pushdown system variable. Use the engine_condition_pushdown flag

of the optimizer_switch variable instead.

• The have_csv, have_innodb, have_ndbcluster, and have_partitioning system variables.

Use SHOW ENGINES instead.

• The sql_big_tables system variable. Use big_tables instead.

• The sql_low_priority_updates system variable. Use low_priority_updates instead.

• The sql_max_join_size system variable. Use max_join_size instead.

• The SLAVE START and SLAVE STOP statements. Use the START SLAVE and STOP SLAVE

statements instead.

• The ONE_SHOT modifier for the SET statement.

(WL #5185, WL #6311)

• Important Change; Replication: Replication filtering options such as --replicate-do-db, --

replicate-rewrite-db, and --replicate-do-table were not consistent with one another in

regard to case sensitivity. Now all --replicate-* options follow the same rules for case sensitivity

applying to names of databases and tables elsewhere in the MySQL server, including the effects of the

lower_case_table_names system variable. (Bug #51639, Bug #11759334)

• Important Change; Replication: Added the MASTER_RETRY_COUNT option to the CHANGE MASTER

TO statement, and a corresponding Master_Retry_Count column to the output of SHOW SLAVE

STATUS. The option sets the value shown in this column. MASTER_RETRY_COUNT is intended eventually

to replace the older (and now deprecated) --master-retry-count server option, and is now the

preferred method for setting the maximum number of times that the slave may attempt to reconnect after

losing its connection to the master. (Bug #44209, Bug #11752887, Bug #44486, Bug #11753110)

• InnoDB: Setting innodb_read_ahead_threshold to 0 disables read-ahead. Prior to 5.6.1, a value

of 0 would trigger a read-ahead upon reading the boundary page of a 64 page extent. (Bug #11763876,

Bug #56646)

280

MySQL 5.6 Release Notes

• InnoDB: InnoDB can now report the total size of the rollback segment, measured in pages. The

value is reported through the information_schema.innodb_metrics table, using the counter

trx_rseg_current_size. You enable and query the counter as follows:

mysql> SET GLOBAL innodb_monitor_enable = 'trx_rseg_current_size';

mysql> SELECT name, count, max_count, comment

-> FROM innodb_metrics WHERE name = 'trx_rseg_current_size';

+-----------------------+-------+-----------+----------------------------------------+

+-----------------------+-------+-----------+----------------------------------------+

| trx_rseg_current_size | 346 | 346 | Current rollback segment size in pages |

+-----------------------+-------+-----------+----------------------------------------+

(Bug #57584)

• Replication: SHOW SLAVE STATUS now displays the actual number of retries for each connection

attempt made by the I/O thread. (Bug #56416, Bug #11763675)

• Replication: Added the Slave_last_heartbeat status variable, which shows when a replication

slave last received a heartbeat signal. The value is displayed using TIMESTAMP format. (Bug #45441)

• Replication: Timestamps have been added to the output of SHOW SLAVE STATUS to show when the

most recent I/O and SQL thread errors occurred. The Last_IO_Error column is now prefixed with

the timestamp for the most recent I/O error, and Last_SQL_Error shows the timestamp for the most

recent SQL thread error. The timestamp values use the format YYMMDD hh:mm:ss in both of these

columns. For more information, see SHOW SLAVE STATUS Statement. (Bug #43535, Bug #11752361,

Bug #64255, Bug #13726435)

• There is now a bind_address system variable containing the value of the --bind-address option.

This enables the address to be accessed at runtime. (Bug #44355, Bug #11752999)

• “Unknown table” error messages that included only the table name now include the database name as

well. (Bug #34750, Bug #11747993)

• Previously, EXPLAIN output for a large union truncated the UNION RESULT row at the end of the list as

follows if the string became too large:

<union1,2,3,4,...>

To make it easier to understand the union boundaries, truncation now occurs in the middle of the string:

<union1,2,3,...,9>

(Bug #30597, Bug #11747073)

• The OpenGIS specification defines functions that test the relationship between two geometry values.

MySQL originally implemented these functions such that they used object bounding rectangles and

returned the same result as the corresponding MBR-based functions. Corresponding versions are now

available that use precise object shapes. These versions are named with an ST_ prefix. For example,

Contains() uses object bounding rectangles, whereas ST_Contains() uses object shapes. For

more information, see Functions That Test Spatial Relations Between Geometry Objects.

There are also now ST_ aliases for existing spatial functions that were already exact. For example,

ST_IsEmpty() is an alias for IsEmpty()

In addition, the IsSimple() and ST_Distance() spatial functions are now implemented, as well as

the set operator functions ST_Difference(), ST_Intersection(), ST_SymDifference(), and

ST_Union(), (Bug #4249, Bug #11744883, WL #1326)

281

MySQL 5.6 Release Notes

• The following items are deprecated and will be removed in a future MySQL release. Where alternatives

are shown, applications should be updated to use them.

• The thread_concurrency system variable.

• The --language server option. Use the lc_messages_dir and lc_messages system variables

instead.

• The --master-retry-count server option. Use the MASTER_RETRY_COUNT option the CHANGE

MASTER TO statement instead.

(WL #5265)

• Support for adding Unicode collations that are based on the Unicode Collation Algorithm (UCA) has

been improved:

• MySQL now recognizes a larger subset of the LDML syntax that is used to write collation descriptions.

In many cases, it is possible to download a collation definition from the Unicode Common Locale Data

Repository and paste the relevant part (that is, the part between the <rules> and </rules> tags)

into the MySQL Index.xml file.

• Character representation in LDML rules is more flexible. Any character can be written literally, not

just basic Latin letters. For collations based on UCA 5.2.0, hexadecimal notation can be used for any

character, not just BMP characters.

• When problems are found while parsing Index.xml, better diagnostics are produced.

• For collations that require tailoring rules, there is no longer a fixed size limit on the tailoring

information.

For more information, see LDML Syntax Supported in MySQL, and Diagnostics During Index.xml

Parsing. (WL #5624)

• TO_BASE64() and FROM_BASE64() functions are now available to perform encoding to and from

base-64 strings. (WL #5510)

282

MySQL 5.6 Release Notes

• The Unicode implementation has been extended to include a utf16le character set, which corresponds

to the UTF-16LE encoding of the Unicode character set. This is similar to utf16 (UTF-16) but is little-

endian rather than big-endian.

Two utf16le collations are available:

• utf16le_general_ci: The default collation, case sensitive (similar to utf16_general_ci).

• utf16le_bin: Case sensitive, with by-codepoint comparison that provides the same order as

utf16_bin.

There are some limitations on the use of utf16le. With the exception of the item regarding user-defined

collations, these are the same as the limitations on ucs2, utf16, and utf32.

• utf16le cannot be used as a client character set, which means that it also does not work for SET

NAMES or SET CHARACTER SET.

• It is not possible to use LOAD DATA to load data files that use utf16le.

• FULLTEXT indexes cannot be created on a column that uses utf16le. However, you can perform IN

BOOLEAN MODE searches on the column without an index.

• The use of ENCRYPT() with utf16le is not recommended because the underlying system call

expects a string terminated by a zero byte.

• It is not possible to create user-defined UCA collations for utf16le because there is no

utf16le_unicode_ci collation, which would serve as the basis for such collations.

(WL #4616)

• Changes to replication in MySQL 5.6 make mysqlbinlog output generated by the --base64-

output=ALWAYS option unusable. ALWAYS is now an invalid value for this option. If the option is given

without a value, the effect is now the same as --base64-output=AUTO rather than --base64-

output=ALWAYS. (WL #5625)

References: See also: Bug #28760.

• Croatian collations were added for Unicode character sets: utf8_croatian_ci, ucs2_croatian_ci,

utf8mb4_croatian_ci, utf16_croatian_ci, and utf32_croatian_ci. Thee collations have

tailoring for Croatian letters: Č, Ć, Dž, Đ, Lj, Nj, Š, Ž. They are based on Unicode 4.0. (WL #5476)

• Several changes were made to optimizer-related system variables:

• The optimizer_switch system variable has new engine_condition_pushdown and

index_condition_pushdown flags to control whether storage engine condition pushdown and

index condition pushdown optimizations are used. The engine_condition_pushdown system

variable now is deprecated. For information about condition pushdown, see Engine Condition

Pushdown Optimization, and Index Condition Pushdown Optimization.

• The optimizer_switch system variable has new mrr and mrr_cost_based flags to control use

of the Multi-Range Read optimization. The optimizer_use_mrr system variable has been removed.

For information about Multi-Range Read, see Multi-Range Read Optimization.

283

MySQL 5.6 Release Notes

• The join_cache_level system variable has been renamed to optimizer_join_cache_level.

This enables a single SHOW VARIABLES LIKE 'optimizer%' statement to show more optimizer-

related settings.

(WL #5116, WL #5197, WL #5639, WL #5692)

• The Block Nested-Loop (BNL) Join algorithm previously used only for inner joins has been extended and

can be employed for outer join operations, including nested outer joins. For more information, see Block

Nested-Loop and Batched Key Access Joins.

In conjunction with this work, a new system variable, optimizer_join_cache_level, controls how

join buffering is done.

• A --bind-address option has been added to a number of MySQL client programs: mysql,

mysqldump, mysqladmin, mysqlbinlog, mysqlcheck, mysqlimport, and mysqlshow. This is

for use on a computer having multiple network interfaces, and enables you to choose which interface is

used to connect to the MySQL server.

A corresponding change was made to the mysql_options() C API function, which now has a

MYSQL_OPT_BIND option for specifying the interface. The argument is a host name or IP address

(specified as a string). (WL #3126)

Bugs Fixed

• Incompatible Change; Replication: The behavior of INSERT DELAYED statements when using

statement-based replication has changed as follows:

Previously, when using binlog_format=STATEMENT, a warning was issued in the client when

executing INSERT DELAYED; now, no warning is issued in such cases.

Previously, when using binlog_format=STATEMENT, INSERT DELAYED was logged as INSERT

DELAYED; now, it is logged as an INSERT, without the DELAYED option.

However, when binlog_format=STATEMENT, INSERT DELAYED continues to be executed as

INSERT (without the DELAYED option). The behavior of INSERT DELAYED remains unchanged when

using binlog_format=ROW: INSERT DELAYED generates no warnings, is executed as INSERT

DELAYED, and is logged using the row-based format.

This change also affects binlog_format=MIXED, because INSERT DELAYED is no longer considered

unsafe. Now, when the logging format is MIXED, no switch to row-based logging occurs. This means that

the statement is logged as a simple INSERT (that is, without the DELAYED option), using the statement-

based logging format. (Bug #54579, Bug #11762035)

References: See also: Bug #56678, Bug #11763907, Bug #57666. This issue is a regression of: Bug

#39934, Bug #11749859.

• Incompatible Change; Replication: When determining whether to replicate a CREATE DATABASE,

DROP DATABASE, or ALTER DATABASE statement, database-level options now take precedence over

any --replicate-wild-do-table options. In other words, when trying to replicate one of these

statements, --replicate-wild-do-table options are now checked if and only if there are no

database-level options that apply to the statement. (Bug #46110, Bug #11754498)

• Incompatible Change: Starvation of FLUSH TABLES WITH READ LOCK statements occurred when

there was a constant load of concurrent DML statements in two or more connections. Deadlock occurred

when a connection that had some table open through a HANDLER statement tried to update data through

284

MySQL 5.6 Release Notes

a DML statement while another connection tried to execute FLUSH TABLES WITH READ LOCK

concurrently.

These problems resulted from the global read lock implementation, which was reimplemented with the

following consequences:

• To solve deadlock in event-handling code that was exposed by this patch, the

LOCK_event_metadata mutex was replaced with metadata locks on events. As a result, DDL

operations on events are now prohibited under LOCK TABLES. This is an incompatible change.

• The global read lock (FLUSH TABLES WITH READ LOCK) no longer blocks DML and DDL on

temporary tables. Before this patch, server behavior was not consistent in this respect: In some cases,

DML/DDL statements on temporary tables were blocked; in others, they were not. Since the main use

cases for FLUSH TABLES WITH READ LOCK are various forms of backups and temporary tables

are not preserved during backups, the server now consistently permits DML/DDL on temporary tables

under the global read lock.

• The set of thread states has changed:

• Waiting for global metadata lock is replaced by Waiting for global read lock.

• Previously, Waiting for release of readlock was used to indicate that DML/DDL

statements were waiting for release of a read lock and Waiting to get readlock was used to

indicate that FLUSH TABLES WITH READ LOCK was waiting to acquire a global read lock. Now

Waiting for global read lock is used for both cases.

• Previously, Waiting for release of readlock was used for all statements that caused an

explicit or implicit commit to indicate that they were waiting for release of a read lock and Waiting

for all running commits to finish was used by FLUSH TABLES WITH READ LOCK.

Now Waiting for commit lock is used for both cases.

• There are two other new states, Waiting for trigger metadata lock and Waiting for

event metadata lock.

(Bug #57006, Bug #11764195, Bug #54673, Bug #11762116)

• Incompatible Change: CREATE TABLE statements (including CREATE TABLE ... LIKE) are now

prohibited whenever a LOCK TABLES statement is in effect.

One consequence of this change is that CREATE TABLE ... LIKE makes the same checks as

CREATE TABLE and does not just copy the .frm file. This means that if the current SQL mode is

different from the mode in effect when the original table was created, the table definition might be

considered invalid for the new mode and the statement will fail. (Bug #42546, Bug #11751609)

• InnoDB; Replication: If the master had innodb_file_per_table=OFF,

innodb_file_format=Antelope (and innodb_strict_mode=OFF), or both, certain CREATE

TABLE options, such as KEY_BLOCK_SIZE, were ignored. This could permit the master to avoid raising

ER_TOO_BIG_ROWSIZE errors.

However, the ignored CREATE TABLE options were still written into the binary log, so that, if the slave

had innodb_file_per_table=ON and innodb_file_format=Barracuda, it could encounter an

285

MySQL 5.6 Release Notes

ER_TOO_BIG_ROWSIZE error while executing the record from the log, causing the slave SQL thread to

abort and replication to fail.

In the case where the master was running MySQL 5.1 and the slave was MySQL 5.5 (or

later), the failure occurred when both master and slave were running with default values for

innodb_file_per_table and innodb_file_format. This could cause problems during upgrades.

To address this issue, the default values for innodb_file_per_table and innodb_file_format

are reverted to the MySQL 5.1 default values—that is, OFF and Antelope, respectively. (Bug #56318,

Bug #11763590)

• InnoDB: If the MySQL Server crashed immediately after creating an InnoDB table, the server could

quit with a signal 11 during the subsequent restart. The issue could occur if the server halted after

InnoDB created the primary index for the table, but before the index definition was recorded in the

MySQL metadata. (Bug #57616)

References: This issue is a regression of: Bug #54582.

• InnoDB: With binary logging enabled, InnoDB could halt during crash recovery with a message referring

to a transaction ID of 0. (Bug #54901, Bug #11762323)

• Replication: Due to changes made in MySQL 5.5.3, settings made in the binlog_cache_size

and max_binlog_cache_size server system variables affected both the binary log statement

cache (also introduced in that version) and the binary log transactional cache (formerly known simply

as the binary log cache). This meant that the resources used as a result of setting either or both

of these variables were double the amount expected. To rectify this problem, these variables now

affect only the transactional cache. The fix for this issue also introduces two new system variables

binlog_stmt_cache_size and max_binlog_stmt_cache_size, which affect only the binary log

statement cache.

In addition, the Binlog_cache_use status variable was incremented whenever either cache was

used, and Binlog_cache_disk_use was incremented whenever the disk space from either cache

was used, which caused problems with performance tuning of the statement and transactional caches,

because it was not possible to determine which of these was being exceeded when attempting to

troubleshoot excessive disk seeks and related problems. This issue is solved by changing the behavior

of these two status variables such that they are incremented only in response to usage of the binary log

transactional cache, as well as by introducing two new status variables Binlog_stmt_cache_use and

Binlog_stmt_cache_disk_use, which are incremented only by usage of the binary log statement

cache.

The behavior of the max_binlog_cache_size system variable with regard to active sessions

has also been changed to match that of the binlog_cache_size system variable: Previously, a

change in max_binlog_cache_size took effect in existing sessions; now, as with a change in

binlog_cache_size, a change in max_binlog_cache_size takes effect only in sessions begun

after the value was changed.

For more information, see System Variables Used with Binary Logging, and Server Status Variables.

(Bug #57275, Bug #11764443)

• Replication: The Binlog_cache_use and Binlog_cache_disk_use status variables were

incremented twice by a change to a table using a transactional storage engine. (Bug #56343, Bug

#11763611)

References: This issue is a regression of: Bug #50038.

286

MySQL 5.6 Release Notes

• Replication: When STOP SLAVE is issued, the slave SQL thread rolls back the current transaction

and stops immediately if the transaction updates only tables which use transactional storage engines.

Previously, this occurred even when the transaction contained CREATE TEMPORARY TABLE statements,

DROP TEMPORARY TABLE statements, or both, although these statements cannot be rolled back.

Because temporary tables persist for the lifetime of a user session (in the case, the replication user),

they remain until the slave is stopped or reset. When the transaction is restarted following a subsequent

START SLAVE statement, the SQL thread aborts with an error that a temporary table to be created (or

dropped) already exists (or does not exist, in the latter case).

Following this fix, if an ongoing transaction contains CREATE TEMPORARY TABLE statements, DROP

TEMPORARY TABLE statements, or both, the SQL thread now waits until the transaction ends, then

stops. (Bug #56118, Bug #11763416)

• Replication: When an error occurred in the generation of the name for a new binary log file, the error

was logged but not shown to the user. (Bug #46166)

References: See also: Bug #37148, Bug #11748696, Bug #40611, Bug #11750196, Bug #43929, Bug

#51019.

• Replication: When lower_case_table_names was set to 1 on the slave, but not on the master,

names of databases in replicated statements were not converted, causing replication to fail on slaves

using case-sensitive file systems. This occurred for both statement-based and row-based replication.

In addition, when using row-based replication with lower_case_table_names set to 1 on the slave

only, names of tables were also not converted, also causing replication failure on slaves using case-

sensitive file systems. (Bug #37656)

• After setting collation_connection to one of the collations for the ucs2 or utf16 character sets, it

was not possible to change the collation thereafter. (Bug #65000, Bug #13970475)

• cmake -DBUILD_CONFIG=mysql_release on Linux previously required libaio to be linked in. Now

it is possible to specify -DIGNORE_AIO_CHECK to build without libaio. (Bug #58955, Bug #11765940)

• A Valgrind failure occurred in fn_format when called from archive_discover. (Bug #58205, Bug

#11765259)

• Passing a string that was not null-terminated to UpdateXML() or ExtractValue() caused the server

to fail with an assertion. (Bug #57279, Bug #11764447)

• In bootstrap mode, the server could not execute statements longer than 10,000 characters. (Bug

#55817, Bug #11763139)

• NULL values were not grouped properly for some joins containing GROUP BY. (Bug #45267, Bug

#11753766)

• A HAVING clause could be lost if an index for ORDER BY was available, incorrectly permitting additional

rows to be returned. (Bug #45227, Bug #11753730)

• The optimizer could underestimate the memory required for column descriptors during join processing

and cause memory corruption or a server crash. (Bug #42744, Bug #11751763)

• The server returned incorrect results for WHERE ... OR ... GROUP BY queries against InnoDB

tables. (Bug #37977, Bug #11749031)

• An incorrectly checked XOR subquery optimization resulted in an assertion failure. (Bug #37899, Bug

#11748998)

287

MySQL 5.6 Release Notes

• A query that could use one index to produce the desired ordering and another index for range access

with index condition pushdown could cause a server crash. (Bug #37851, Bug #11748981)

• With index condition pushdown enabled, InnoDB could crash due to a mismatch between what

pushdown code expected to be in a record versus what was actually there. (Bug #36981, Bug

#11748647)

• The range optimizer ignored conditions on inner tables in semijoin IN subqueries, causing the optimizer

to miss good query execution plans. (Bug #35674, Bug #11748263)

• A server crash or memory overrun could occur with a dependent subquery and joins. (Bug #34799, Bug

#11748009)

• Selecting from a view that referenced the same table in the FROM clause and an IN clause caused a

server crash. (Bug #33245)

• Deeply nested subqueries could cause stack overflow or a server crash. (Bug #32680, Bug #11747503)

• The server crashed on optimization of queries that compared an indexed DECIMAL column with a string

value. (Bug #32262, Bug #11747426)

• The server crashed on optimizations that used the range checked for each record access

method. (Bug #32229, Bug #11747417)

• Contains() failed for multipolygon geometries. (Bug #32032, Bug #11747370)

• If the optimizer used a Multi-Range Read access method for index lookups, incorrect results could occur

for rows that contained any BLOB or TEXT data types. (Bug #30622, Bug #11747076)

• Compared to MySQL 5.1, the optimizer failed to use join buffering for certain queries, resulting in slower

performance for those queries. (Bug #30363, Bug #11747028)

• For Multi-Range Read scans used to resolve LIMIT queries, failure to close the scan caused file

descriptor leaks for MyISAM tables. (Bug #30221, Bug #11746994)

• SHOW CREATE DATABASE did not account for the value of the lower_case_table_names system

variable. (Bug #21317, Bug #11745926)

Changes in MySQL 5.6.0 (Not released, Milestone 4)

Note

This is a milestone release, for use at your own risk. Upgrades between milestone

releases (or from a milestone release to a GA release) are not supported.

Significant development changes take place in milestone releases and you may

encounter compatibility issues, such as data format changes that require attention

in addition to the usual procedure of running mysql_upgrade. For example, you

may find it necessary to dump your data with mysqldump before the upgrade and

reload it afterward. (Making a backup before the upgrade is a prudent precaution in

any case.)

• Deprecation and Removal Notes

• Performance Schema Notes

• Globally Unique Server IDs

288

MySQL 5.6 Release Notes

• Functionality Added or Changed

• Bugs Fixed

Deprecation and Removal Notes

• Replication: These unused and deprecated items have been removed: the --init-rpl-role and

--rpl-recovery-rank options, the rpl_recovery_rank system variable, and the Rpl_status

status variable. (Bug #54649, Bug #11762095)

References: See also: Bug #34437, Bug #11747900, Bug #34635, Bug #11747961.

• In MySQL 5.5, setting optimizer_search_depth to the deprecated value of 63 switched to the

algorithm used in MySQL 5.0.0 (and previous versions) for performing searches. The value of 63 is now

treated as invalid. (WL #5369)

Performance Schema Notes

• The Performance Schema now includes instrumentation for table input and output. Instrumented

operations include row-level accesses to persistent base tables or temporary tables. Operations that

affect rows are fetch, insert, update, and delete. For a view, waits are associated with base tables

referenced by the view. (WL #4895)

Globally Unique Server IDs

• Replication: Globally unique IDs for MySQL servers were implemented. A UUID is now obtained

automatically when the MySQL server starts. The server first checks for a UUID written in the auto.cnf

file (in the server's data directory), and uses this UUID if found. Otherwise, the server generates a new

UUID and saves it to this file (and creates the file if it does not already exist). This UUID is available as

the server_uuid system variable.

MySQL replication masters and slaves know each other's UUIDs. The value of a slave's UUID can be

read in the output of SHOW SLAVE HOSTS. After a slave is started using START SLAVE, the value of

the master's UUID is available on the slave in the output of SHOW SLAVE STATUS. (Bug #33815, Bug

#11747723, WL #4677)

References: See also: Bug #16927, Bug #11745543.

Functionality Added or Changed

• Partitioning: It is now possible to exchange a partition of a partitioned table or a subpartition of a

subpartitioned table with a nonpartitioned table that otherwise has the same structure using the ALTER

TABLE ... EXCHANGE PARTITION statement. This can be used, for example, for importing and

exporting partitions.

For more information and examples, see Exchanging Partitions and Subpartitions with Tables. (WL

#4445)

• Replication: The SHOW SLAVE STATUS statement now has a Master_Info_File field indicating the

location of the master.info file. (Bug #50316, Bug #11758151)

• Replication: MySQL now supports delayed replication such that a slave server deliberately lags

behind the master by at least a specified amount of time. The default delay is 0 seconds. Use the new

MASTER_DELAY option for CHANGE MASTER TO to set the delay to N seconds:

CHANGE MASTER TO MASTER_DELAY = N;

289

MySQL 5.6 Release Notes

An event received from the master is not executed until at least N seconds later than its execution on the

master.

START SLAVE and STOP SLAVE take effect immediately and ignore any delay. RESET SLAVE resets

the delay to 0.

SHOW SLAVE STATUS has three new fields that provide information about the delay:

• SQL_Delay: The number of seconds that the slave must lag the master.

• SQL_Remaining_Delay: When Slave_SQL_Running_State is Waiting until

MASTER_DELAY seconds after master executed event, this field contains the number of

seconds left of the delay. At other times, this field is NULL.

• Slave_SQL_Running_State: The state of the SQL thread (analogous to Slave_IO_State). The

value is identical to the State value of the SQL thread as displayed by SHOW PROCESSLIST.

When the slave SQL thread is waiting for the delay to elapse before executing an event, SHOW

PROCESSLIST displays its State value as Waiting until MASTER_DELAY seconds after

master executed event.

The relay-log.info file now contains the delay value, so the file format has changed. See

Replication Metadata Repositories. In particular, the first line of the file now indicates how many lines are

in the file. If you downgrade a slave server to a version older than MySQL 5.6, the older server will not

read the file correctly. To address this, modify the file in a text editor to delete the initial line containing

the number of lines.

The introduction of delayed replication entails these restrictions:

• Previously the BINLOG statement could execute all types of events. Now it can execute only format

description events and row events.

• The output from mysqlbinlog --base64-output=ALWAYS cannot be parsed. ALWAYS becomes

an invalid value for this option in 5.6.1.

For additional information, see Delayed Replication. (Bug #28760, Bug #11746794, WL #344)

• The Romansh locale 'rm_CH' is now a permissible value for the lc_time_names system variable.

(Bug #50915, Bug #11758678, WL #5303)

• mysqlbinlog now has a --binlog-row-event-max-size option to enable large row events to be

read from binary log files. (Bug #49932)

• mysqldump now has an --add-drop-trigger option which adds a DROP TRIGGER IF EXISTS

statement before each dumped trigger definition. (Bug #34325, Bug #11747863)

• Vietnamese collations were added for the Unicode character sets. Those based on Unicode

Collation Algorithm 5.2.0 have names of the form xxx_vietnamese_520_ci (for example,

utf8_vietnamese_520_ci). Those based on Unicode Collation Algorithm 4.0.0 have names of the

form xxx_vietnamese_ci (for example, utf8_vietnamese_ci). These collations are the same as

the corresponding xxx_unicode_520_ci and xxx_unicode_ci collations except for precomposed

characters which are accented versions of “A”, “D”, “E”, “O”, and “U”. There is no change to ideographic

characters derived from Chinese. There are no digraphs. (WL #3865)

• Unicode collation names now may include a version number to indicate the Unicode Collation Algorithm

(UCA) version on which the collation is based. Initial collations thus created use version UCA 5.2.0. For

290

MySQL 5.6 Release Notes

example, utf8_unicode_520_ci is based on UCA 5.2.0. UCA-based Unicode collation names that do

not include a version number are based on version 4.0.0.

LOWER() and UPPER() perform case folding according to the collation of their argument. A character

that has uppercase and lowercase versions only in a Unicode version more recent than 4.0.0 will be

converted by these functions only if the argument has a collation that uses a recent enough UCA

version.

The LDML rules for creating user-defined collations are extended to permit an optional version

attribute in <collation> tags to indicate the UCA version on which the collation is based. If the

version attribute is omitted, its default value is 4.0.0. See Adding a UCA Collation to a Unicode

Character Set. (WL #2673)

• The Unicode character sets now have a xxx_german2_ci collation that provides DIN-2 (phone book)

ordering (for example, utf8_german2_ci). See Unicode Character Sets. (WL #4013)

• mysqlbinlog now has the capability to back up a binary log in its original binary format. When invoked

with the --read-from-remote-server and --raw options, mysqlbinlog connects to a server,

requests the log files, and writes output files in the same format as the originals. See Using mysqlbinlog

to Back Up Binary Log Files. (WL #4783)

• A new SQL function, WEIGHT_STRING(), returns the weight string for an input string. The weight string

represents the sorting and comparison value of the input string. See String Functions and Operators.

(WL #3716)

Bugs Fixed

• Security Fix: A security bug was fixed. (Bug #49124)

• InnoDB: The server could crash on shutdown, if started with --innodb-use-system-malloc=0.

(Bug #55581, Bug #11762927)

• Replication: The internal flag indicating whether a user value was signed or unsigned

(unsigned_flag) could sometimes change between the time that the user value was recorded for

logging purposes and the time that the value was actually written to the binary log, which could lead to

inconsistency. Now unsigned_flag is copied when the user variable value is copied, and the copy of

unsigned_flag is then used for logging. (Bug #51426, Bug #11759138)

References: See also: Bug #49562, Bug #11757508.

• Microsoft Windows: On Windows, an IPv6 connection to the server could not be made using an IPv4

address or host name. (Bug #52381, Bug #11760016)

• Microsoft Windows: On Windows, the my_rename() function failed to check whether the source file

existed. (Bug #51861, Bug #11759540)

• Microsoft Windows: On Windows, mysqlslap crashed for attempts to connect using shared memory.

(Bug #31173, Bug #11747181, Bug #59107, Bug #11766072)

• The embedded server could crash when determining which directories to search for option files. (Bug

#55062, Bug #11762465)

• Performance Schema code was subject to a buffer overflow. (Bug #53363)

• Subquery execution for EXPLAIN could be done incorrectly and raise an assertion. (Bug #52317, Bug

#11759957)

291

MySQL 5.6 Release Notes

• There was a mixup between GROUP BY and ORDER BY concerning which indexes should be considered

or permitted during query optimization. (Bug #52081, Bug #11759746)

• The ref column of EXPLAIN output for subquery lines could be missing information. (Bug #50257, Bug

#11758106)

• Passwords for CREATE USER statements were written to the binary log in cleartext rather than in

ciphertext. (Bug #50172)

• The BLACKHOLE storage engine failed to load on Solaris and OpenSolaris if DTrace probes had been

enabled. (Bug #47748, Bug #11755909)

• Some error messages included a literal mysql database name rather than a parameter for the database

name. (Bug #46792, Bug #11755079)

• In the ER_TABLEACCESS_DENIED_ERROR error message, the command name parameter could be

truncated. (Bug #45355, Bug #11753840)

• To forestall the occurrence of possible relocation errors in the future, libmysys, libmystrings, and

libdbug have been changed from normal libraries to “noinst” libtool helper libraries, and are no

longer installed as separate libraries. (Bug #29791, Bug #11746931)

• A suboptimal query execution plan could be chosen when there were several possible range and ref

accesses. Now preference is given to the keys that match the most parts and choosing the best one

among them. (Bug #26106, Bug #11746406)

• Searches for data on a partial index for a column using the utf8 character set failed. (Bug #24858)

• For queries with GROUP BY, FORCE INDEX was not ignored as it should have been when it would result

in a more expensive query execution plan. (Bug #18144, Bug #11745649)

Index

Symbols

!=, 176

--add-drop-trigger, 288

--all-databases, 230

--base64-output, 121, 243

--binary-as-hex, 12, 20

--binary-mode, 243

--bind-address, 278

--binlog-checksum, 265

--binlog-ignore-db, 121

--binlog-row-event-max-size, 288

--bootstrap, 166, 191

--connect-expired-password, 121

--database, 121, 214

--default-auth, 265

--defaults-extra-file, 243

--defaults-file, 265

--disable-gtid-unsafe-statements, 176

--dump-slave, 121

--enable-cleartext-plugin, 44

--exclude-gtids, 121

--flush-logs, 214

292

MySQL 5.6 Release Notes

--gtid-mode, 214

--gtid_mode, 82

--help, 86

--hexdump, 230

--histignore, 166

--ignore-db-dir, 243

--include-gtids, 121

--include-master-host-port, 121

--init-rpl-role, 288

--log-bin, 147, 214

--log-slave-updates, 121

--log-warnings, 86

--malloc-lib, 5

--master-data, 230

--no-beep, 12

--plugin-dir, 166, 265

--plugin-load, 243

--plugin-load-add, 243

--print-defaults, 54

--raw, 75, 243

--read-from-remote-server, 121

--relay-log, 214

--relay-log-info-file, 105

--relay-log-recovery, 191

--relay-log-space-limit, 191

--replicate-do-db, 82

--replicate-ignore-db, 82

--replicate-ignore-table, 176

--replicate-rewrite-db, 176

--replicate-wild-ignore-table, 121

--report-port, 214

--routines, 214

--rpl-recover-rank, 288

--secure-auth, 86, 131

--server-id, 214, 243

--single-transaction, 214

--skip-gtids, 121

--skip-innodb, 70, 147

--skip-slave-start, 214

--slave-skip-errors, 166

--slave-skip-errors=all, 86

--slave-sql-verify-checksum, 265

--slow-start-timeout, 214

--ssl, 37

--ssl-cipher, 7

--ssl-crl, 243

--ssl-crlpath, 243

--ssl-key, 176, 243

--ssl-mode, 22, 37

--ssl-mode=VERIFY_IDENTITY, 13

--ssl-verify-server-cert, 13, 37

--start-position, 214, 243

--stop-never, 121

--verbose, 98, 121, 265

293

MySQL 5.6 Release Notes

--write-binlog, 176

--xml, 214

.frm, 111

.par, 111

64-bit, 176

adaptive_hash_searches_btree, 63

ADD, 58

ADD FOREIGN KEY, 71

ADD FULLTEXT, 98

ADD INDEX, 40, 63

ADD PARTITION, 214

ADD PRIMARY KEY, 105, 131

AES_DECRYPT(), 86, 105, 121, 147

AES_ENCRYPT(), 86, 105, 147

AGAINST, 92

aggregate functions, 166, 214

ALGORITHM, 9, 66, 111, 131

ALL, 15

ALL_SIGNED, 111

ALL_UNSIGNED, 111

ALTER DATABASE, 265, 279

ALTER EVENT, 243

ALTER SERVER, 176

ALTER TABLE, 9, 12, 15, 17, 27, 31, 40, 44, 46, 50, 54, 58, 63, 66,

71, 75, 86, 92, 98, 98, 105, 111, 121, 131, 147, 157, 176, 191, 214, 230, 243,

265, 288

ALTER TABLE INPLACE, 121

ALTER USER, 166, 176, 191

ANALYZE TABLE, 40

AND, 7

append, 58

Append_block events, 243

ARCHIVE, 85, 131, 191, 214, 230

ARM64, 46

assertion, 92, 105, 111, 121, 131, 166

assertion failure, 105

asterisk, 111

attribute promotion, 111, 243

audit_log plugin, 8, 15, 37, 46, 58, 63, 71, 75, 86, 111, 121

authentication, 86, 98, 131, 157, 166, 230, 265

authentication plugins, 265

auto-increment, 86

auto.cnf, 82, 288

autocommit, 44, 105, 131, 265

AUTOMATIC, 75, 121

automatic_sp_privileges, 13

AUTO_INCREMENT, 46, 75, 131, 147, 191, 243, 265

auto_increment_increment, 8

AUTO_POSITION, 131

Auto_Position, 147

avoid_temporal_upgrade, 58

294

MySQL 5.6 Release Notes

B-tree, 66

backport, 86

backticks, 131, 166

backup, 54, 86

barracuda, 105

BEGIN, 191

BETWEEN, 214

BIGINT, 214

binary log, 31, 33, 37, 44, 46, 63, 66, 71, 92, 98, 105, 121, 131, 147, 176,

243, 265

binary log events, 86, 131

binary log rotation, 111

bind-address, 279

bind_address, 176, 191, 279

binlog, 66, 75, 82, 98, 121, 131, 147, 157

BINLOG, 288

binlog events, 147

binlog rotation, 121

Binlog_cache_disk_use, 279

binlog_cache_size, 279

Binlog_cache_use, 279

binlog_cache_use, 279

binlog_checksum, 191, 265

BINLOG_DUMP_NON_BLOCK, 75

binlog_error_action, 40, 46

binlog_format, 121, 166, 279

binlog_rows_query_log_events, 191, 265

binlog_row_image, 54, 98, 265

Binlog_stmt_cache_disk_use, 279

binlog_stmt_cache_size, 279

Binlog_stmt_cache_use, 279

BIN_LOG_HEADER_SIZE , 214

BLACKHOLE, 121

blackhole, 288

BLOB, 66, 75, 86, 105, 121, 243

block nested loop, 279

block_encryption_mode, 86

boolean mode, 37, 98, 111

btr0cur.cc, 92

btr_root_raise_and_insert, 63

btr_validate_level, 98

buf0flu.cc, 105

buffer manager, 121

buffer pool, 19, 40, 82, 86, 105, 111, 131

buf_page_get_gen, 105

buf_validate, 121

build error, 86

C API, 20, 22, 31, 33, 37, 40, 44, 54, 82, 98, 105, 111, 121, 131, 147, 214

cache_policies, 92

Can't find record, 243

295

MySQL 5.6 Release Notes

CASE operator, 121

change buffer, 50, 63, 98

CHANGE COLUMN, 66

CHANGE MASTER TO, 98, 105, 111, 131, 147, 176, 191, 214, 230, 265, 279, 288

CHAR, 214

character sets, 27, 33, 40, 46, 58, 66, 71, 82, 86, 92, 131, 157, 176, 191,

243, 265, 288

CHARSET, 131

charset2html, 82

CHECK TABLE, 98, 111, 157, 176, 243

checksum, 44, 66

CHECKSUM TABLE, 230

checksums, 265

cleartext_plugin, 176

client, 214

client API, 75

clients, 54

CLIENT_CAN_HANDLE_EXPIRED_PASSWORDS mysql_real_connect() option, 147

CLIENT_REMEMBER_OPTIONS, 71

close_temporary_tables(), 75

clustered index, 131

CMake, 44, 86, 111, 121, 166, 176, 191, 243

cmp_dtuple_rec_with_match, 86

collations, 176, 191, 214, 279, 288

column length, 58

comment, 111

comments, 7, 191, 265

COMMIT, 166, 191

commit_threads_m, 111

comparison operators, 214

compilation, 265

compiling, 7, 9, 15, 17, 20, 22, 27, 31, 35, 40, 44, 46, 50, 54, 58,

63, 66, 75, 82, 86, 92, 98, 105, 111, 176, 191, 288

compressed slave, 71

compressed table, 71, 86

compression, 12, 50

COM_BINLOG_DUMP, 214

COM_CHANGE_USER, 111

COM_STATISTICS, 214

Com_xxx, 191

CONCAT(), 4, 6, 191, 243

CONCAT_WS(), 4, 6

concurrent transactions, 214

condition pushdown, 265

configuration, 5, 7, 17, 22, 40, 58, 66, 75, 86, 92, 98, 121, 131, 166, 176,

191, 214, 230, 243, 265, 279

connection-server-id, 75

connections, 243

CONNECTION_CONTROL, 15

CONNECTION_CONTROL plugin, 22, 27

CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS plugin, 27

CONNECTION_ID(), 157

consistency, 82

constraint violation, 46

296

MySQL 5.6 Release Notes

constraints, 63, 111

containers table, 98

Contains(), 279

CONV(), 98

conversion, 98

CONVERT_TZ(), 131

corruption, 92, 121

COUNT(), 20

counter, 98

CPU, 75

crash recovery, 66, 86, 121, 131

CRC32, 131

CREATE ... SELECT, 265

CREATE DATABASE, 279

CREATE EVENT, 243

CREATE FUNCTION, 191

CREATE INDEX, 44, 191

CREATE SERVER, 176

CREATE TABLE, 19, 22, 37, 46, 54, 66, 86, 98, 111, 131, 191, 243, 279

CREATE TABLE ... SELECT, 82, 214

CREATE TABLE LIKE, 105

CREATE TEMPORARY TABLE, 82, 243

CREATE USER, 35, 166, 243, 288

CREATE VIEW, 214

Create_file events, 243

CREATE_TIME, 54

curl, 12

current_thd, 63

data corruption, 71, 98

data dictionary, 63, 66

DATA DIRECTORY, 37, 54

data file, 44, 86

data file path, 40

data file size, 86

data integrity, 176

data types, 86, 131, 230

database, 147

database name, 66, 98

DATE(), 214, 243

DATETIME, 214, 265

DB_PRODUCTION, 86

DDL, 35, 40, 92, 214

deadlock, 35, 58, 121

deadlocks, 243

Debian, 66

debug, 66, 71, 92, 121

debug assertion, 92

debug build, 86, 166

Debug Sync, 22, 82, 214

DECIMAL, 13, 92, 105, 230

decr, 58, 63

297

MySQL 5.6 Release Notes

default database, 121

default storage engine, 98

DEFAULT_AUTH, 230

default_tmp_storage_engine, 243

DELETE, 13, 63

Delete_rows_log_event, 121

deprecation, 40, 58, 66, 71, 75, 82, 86, 92, 105, 111, 131, 157, 166, 176, 191,

214, 279, 288

DES_DECRYPT(), 265

DES_ENCRYPT(), 265

dictionary, 50

DICT_CHECK_TABLESPACES_AND_STORE_MAX_ID, 121

DICT_FK_MAX_RECURSIVE_LOAD, 121

dict_set_corrupted, 66

dict_update_statistics, 121

DISCARD TABLESPACE, 92, 98

disconnect_on_expired_password system variable, 147

disk full, 44, 131, 166

DISTINCT, 166

DIV, 265

DML, 40, 58, 63, 147, 214, 265

Docker, 19

doublewrite buffer, 86, 92

downgrades, 37

DROP DATABASE, 50, 105, 121, 191, 214, 243, 265, 279

DROP INDEX, 35, 44, 105, 121

DROP SERVER, 176

DROP TABLE, 75, 98, 111, 131, 147, 214

DROP TEMPORARY TABLE, 82, 105

DROP TRIGGER, 86

DROP USER, 166

DTrace, 71, 75

dump thread, 46, 86, 98, 105

duplicate key, 121

duplicate key error, 8, 44

duplicate key value, 71

EE_FILENOTFOUND, 243

EIO, 75

el5, 22

el6, 20

empty transactions, 82

encryption, 4, 5, 7, 9, 11, 13, 17, 20, 22, 27, 31, 35, 37, 40, 44,

46, 63, 66, 71, 86

enforce-gtid-consistency, 157

engine_condition_pushdown, 279

ENOSPC, 75

enter value, 35, 46

ENUM, 131

EOF, 131

Error 1034, 98

Error 1160, 214

298

MySQL 5.6 Release Notes

Error 1168, 214

Error 1201, 191

error 2006, 214

error 2013, 214

error code, 92

error handling, 75, 121

error log, 86, 98, 166, 176, 243

error logging, 166

error message, 63, 71, 86, 105, 131, 166, 191, 243

errors, 12, 15, 27, 31, 35, 37, 40, 46, 58, 63, 86, 98, 105, 111, 121, 131,

147, 157, 166, 176, 191, 214, 230, 243, 265, 279, 288

ERROR_FOR_DIVISION_BY_ZERO, 86

error_key_num, 98

Error_log_throttle, 86

ERR_LOCK_WAIT_TIMEOUT, 46

ER_AUTO_POSITION_REQUIRES_GTID_MODE_ON, 191

ER_BINLOG_UNSAFE_STATEMENT, 176

ER_GTID_NEXT_TYPE_UNDEFINED_GROUP, 46, 71

ER_SLAVE_IGNORE_TABLE, 86

ER_SLAVE_INCIDENT, 243

ER_UNKNOWN_SYSTEM_VARIABLE, 131

event checksums, 46

event offsets, 92

event scheduler, 105, 121, 166

events, 63, 214

exact search, 98

EXCHANGE PARTITION, 191, 243, 288

Executed_Gtid_Set, 46, 147

exec_time, 92

expiration time, 58

expired passwords, 147

EXPLAIN, 82, 131, 147, 157, 166, 176, 214, 279, 288

EXPLAIN EXTENDED, 243, 265

explain_filename, 121

explicit_defaults_for_timestamp, 176, 191

export, 63

exptime, 54, 58

EXTRACT(), 265

ExtractValue(), 37, 92, 176, 279

failover, 147

FEDERATED, 31, 37, 58, 63, 92, 121, 176, 214, 230

Fedora, 35

Field_tiny::pack(), 4

file format, 46, 105

file size, 92

FILES, 5

files, 214

FILE_PAGE_WAS_FREED, 147

filtering options, 279

fil_node_open_file, 105

FIND_IN_SET(), 265

299

MySQL 5.6 Release Notes

firewall, 44, 50, 54, 58

FLOAT, 214

flush, 17

FLUSH LOGS, 166, 191

flush method, 50

FLUSH TABLES, 17, 35, 63, 82, 86, 121

FLUSH TABLES WITH READ LOCK, 111

flush_all, 46, 58

FOR EXPORT, 63, 86

FORCE INDEX, 13

force recovery, 98

FOREIGN KEY, 111

foreign key constraint, 12, 105, 121

foreign keys, 13, 35, 50, 54, 63, 71, 75, 86, 111, 131, 176

foreign_key_checks, 111, 121

format descriptors, 131

FORMAT(), 131

formatting, 20

FOUND_ROWS(), 111, 121, 131

FreeBSD, 243, 265

FROM_BASE64(), 279

fsync(), 121

fts0vlc.ic, 58

fts_add_doc_by_id, 66

FTS_CHILD_EXITING, 131

fts_optimize_thread, 66

fts_tokenizer_word_get, 66

full-text, 33, 63, 66, 75, 92, 98, 105, 111, 121, 147

full-text index, 33, 35, 37, 40, 50, 98

full-text search, 4, 4, 8, 15, 17, 19, 27, 31, 35, 37, 40, 50, 54, 58,

63, 66, 75, 82, 86, 92, 98, 111, 121, 131, 147, 191

FULLTEXT index, 13, 35, 58, 157, 230

function, 66

functions, 98

GCC, 46

gcov, 191

general_log, 191

get, 71

GET DIAGNOSTICS, 230

get_string_length(), 98

GIS, 15, 17, 33, 54, 71, 98, 111, 121, 147, 166, 176, 279

glibc, 27

global locks, 111

GRANT, 98, 166, 176

GROUP BY, 5

group commit, 121

GROUP_CONCAT(), 121, 191, 230

group_concat_max_len, 58, 191

group_relay_log_pos, 82

GTID, 20, 40, 50, 54, 58, 63, 66, 71, 121, 191

gtid-mode, 157

300

MySQL 5.6 Release Notes

GTIDs, 46, 71, 75, 98, 111, 121, 131, 147, 157, 176, 191, 214

gtid_executed, 131

GTID_log_event, 121

gtid_mode, 58, 82, 147, 166

gtid_next, 71, 75, 111, 121, 131

GTID_NEXT_LIST, 111

gtid_purged, 131, 157

GTID_SUBSET(), 131

GTID_SUBTRACT(), 131, 157

HANDLER, 191, 230

hang, 75, 86, 98, 166

HASH, 92, 176, 214

hash_lock arrayk, 131

HASH_SCAN, 71

have_profiling, 166

HAVING, 121, 214

HA_ERR_KEY_NOT_FOUND, 92

ha_innobase, 105

header, 75

heap block, 92

heartbeat, 279

heartbeats, 131

HEARTBEAT_LOG_EVENT, 131

Heartbleed, 85

history list, 17

hostname, 166

host_cache, 214

host_cache_size, 214

I/O cache, 92

ibd file, 44

ibdata, 44

identifiers, 131, 166

IF EXISTS, 105

IF(), 121

ignore_db_dirs, 243

implicit commit, 121, 131, 147, 176, 214

IMPORT TABLESPACE, 44, 50, 131

Important Change, 75, 86, 105, 111, 121, 131, 147, 157, 166, 176, 191, 214, 230, 243,

265, 279

Important Note, 131

impossible WHERE, 166

IN, 11

Incompatible Change, 5, 17, 27, 31, 33, 86, 98, 105, 111, 121, 131, 157, 176,

191, 214, 230, 243, 265, 279

incr, 63

index, 98, 111, 214

INDEX DIRECTORY, 54

index files, 214

index key, 166

301

MySQL 5.6 Release Notes

index merge, 243

index page, 111

index record, 46

index scan, 111

index tables, 75

index_merge, 92

index_merge_intersection, 86

index_next, 98

index_read_map, 98

INET6_ATON(), 131, 243

INET6_NTOA(), 131, 243

infinite loop, 105

info repository, 147

INFORMATION_SCHEMA, 4, 5, 54, 58, 63, 82, 147, 214

information_schema, 98, 265

INFORMATION_SCHEMA.INNODB_METRICS, 111

INFORMATION_SCHEMA.PARTITIONS, 54, 105, 191

INFORMATION_SCHEMA.TABLES, 9, 54, 82

initialize, 92

init_command, 214

init_file, 265

innobase_get_col_names, 92

innobase_rollback, 111

innochecksum, 92

InnoDB, 4, 4, 6, 8, 9, 12, 13, 15, 17, 19, 20, 22, 27, 31, 33,

35, 37, 40, 44, 46, 50, 54, 58, 63, 66, 71, 75, 82, 86, 92, 98, 105,

111, 121, 131, 147, 157, 166, 176, 191, 214, 230, 243, 265, 279, 288

InnoDB Lock Monitor, 66

InnoDB Monitor, 66

innodb_additional_mem_pool_size, 243

innodb_allocate, 92

innodb_api_enable_binlog, 92

innodb_api_enable_mdl, 131

innodb_buffer_pool_size, 98

INNODB_BUFFER_POOL_SIZE, 121

innodb_checksum_algorithm, 54, 66

innodb_data_file_path, 75

innodb_fast_shutdown, 111

innodb_file_format, 279

innodb_file_per_table, 147, 279

innodb_force_recovery, 46, 66, 98

innodb_ft_default_stopword, 131

INNODB_FT_INDEX_TABLE, 98

innodb_index_stats, 86

innodb_limit_optimistic_insert_debug, 66

innodb_locks_unsafe_for_binlog, 243

innodb_log_buffer_size, 121

innodb_log_file_size, 63

innodb_log_group_home_dir, 105

innodb_max_purge_lag, 214

INNODB_MEMCACHE.CONTAINERS, 176

INNODB_METRICS, 63

innodb_metrics, 98

innodb_mirrored_log_groups, 131

302

MySQL 5.6 Release Notes

innodb_monitor_enable, 33

innodb_numa_interleave, 46

innodb_read_only, 111

innodb_rwlock_x_spin_waits, 111

innodb_stats_on_metadata, 105

innodb_stats_sample_pages, 243

innodb_strict_mode, 66

innodb_sync_array_size, 131

innodb_table_monitor, 243

innodb_tmpdir, 40

innodb_use_sys_malloc, 243

INPLACE, 66, 92, 131

INSERT, 13, 35, 63, 71, 86, 105, 111, 121, 191

INSERT ... SELECT, 214

insert buffer, 46

insert buffer merge, 111

INSERT DELAYED, 176, 191, 279

INSERT IGNORE, 265

INSERT ON DUPLICATE KEY UPDATE, 191, 243, 265

insert operations, 166

INSERT_ID, 147, 214

INSTALL PLUGIN, 8, 33

installing, 8, 9, 13, 19, 20, 22, 27, 33, 35, 44, 50, 63, 66, 71, 75,

86, 92, 98, 111, 121, 131, 191, 230, 243, 265

INT, 214

invalid page type, 111

invalid pointer, 111

inverse document frequency, 75

IPv6, 176, 191, 243

IS NULL, 265

isl file, 92

isolation level, 105

IS_FREE_LOCK(), 66

IS_IPV4(), 243

IS_IPV4_COMPAT(), 243

IS_IPV4_MAPPED(), 243

IS_IPV6(), 243

IS_USED_LOCK(), 66

Item::print, 243

I_S.INNODB_TEMP_TABLE_INFO, 82

joins, 121, 279

KEY, 66, 176, 214

KILL, 15, 98, 157

Last_Error, 111

LAST_INSERT_ID, 98

LAST_INSERT_ID(), 157, 191

Last_IO_Error, 243

303

MySQL 5.6 Release Notes

Last_SQL_Error, 111, 243

LDML, 279

lettercase, 279

libedit, 131, 230, 243

libevent, 9, 92

libmysqlclient, 166

libmysqlclient version, 35

libmysqld, 40, 131, 191, 214, 243, 288

LIBMYSQL_PLUGIN_DIR, 147

libraries, 288

licensing, 265

LIKE, 157, 191, 265

LIMIT, 176

limitations, 86

linefeeds, 214

LinuxThreads, 75

LIST, 19, 214

LIST COLUMNS, 75

LOAD DATA, 75, 111, 157, 243, 265

LOAD DATA ... SET, 98

LOAD INDEX INTO CACHE, 214

LOAD XML, 20, 46

locale, 288

lock monitor, 92

LOCK TABLES, 4, 214, 279

locking, 4, 15, 46, 50, 63, 66, 71, 75, 86, 92, 98, 105, 111, 121, 131,

147, 157, 166, 176, 191, 214, 230, 243, 265, 279

LOCK_ORDINARY, 121

LOCK_REC_NOT_GAP, 121

lock_rec_restore_from_page_infimum, 111

lock_validate, 131

log buffer, 98

log error, 71

log file corruption, 121

log files, 121

log rotation, 46, 105, 121, 131

log tables, 157, 230

log-bin, 176, 265

log-slave-updates, 105

logging, 27, 31, 37, 54, 58, 63, 71, 86, 98, 105, 121, 147, 157, 166, 191,

214, 230, 243, 265

loggins, 243

log_bin_basename, 265

log_event.h, 111

log_slow_admin_statements, 131

log_slow_slave_statements, 131

log_throttle_queries_not_using_indexes, 214

log_warnings, 92

lost connection, 37

LOST_EVENTS, 98

lowercase, 66

lower_case_table_names, 46, 230, 243, 279

LOW_PRIORITY, 214

LPAD(), 71

304

MySQL 5.6 Release Notes

LRU flushing, 121

LSN, 66, 105, 121

MAKETIME(), 191

make_win_bin_dist, 230

mapping_db_to_worker, 176

Masrter_id, 176

master info repository, 111

master thread, 71

master-bind, 265

master-slave protocol, 157

master.info, 243

MASTER_AUTO_POSITION, 98, 147, 157, 191, 214

MASTER_DELAY, 105, 191

master_info_repository, 71, 86, 105, 147, 176, 265

MASTER_LOG_FILE, 265

MASTER_PASSWORD, 111, 230

MASTER_POS_WAIT(), 147

MASTER_RETRY_COUNT, 279

MASTER_SSL_CRL, 86

MASTER_SSL_CRLPATH, 86

MASTER_USER, 111, 230

master_verify_checksum, 265

MATCH, 92

MAX(), 15, 191, 214, 243

max_allowed_packet, 191, 243, 265

max_binlog_cache_size, 86, 176, 279

max_binlog_stmt_cache_size, 176, 279

max_connections, 131, 214

max_connect_errors, 166

max_digest_length, 50

max_long_data_size, 243

max_sort_length, 4

MAX_USER_CONNECTIONS, 191

MD5(), 191

MDEV-6615, 46

memcached, 6, 12, 13, 19, 20, 22, 35, 46, 50, 54, 58, 63, 71, 75, 86,

92, 98, 105, 111, 121

memcached plugin, 176

memcpy, 86

memmove, 86

MEMORY, 12, 157, 214, 230

memory, 20, 71, 75, 86, 92, 98

memory access error, 86

memory access violation, 66, 71, 86, 92

memory allocation, 46

memory consumption, 111

memory leak, 98, 111, 121

memory usage, 71, 92

memset, 82

MEM_HEAP_CREATE_BLOCK, 121

MERGE, 12, 214, 243

305

MySQL 5.6 Release Notes

merge, 111

merge insert buffer, 92

metadata, 63, 191

Microsoft Windows, 8, 9, 11, 12, 17, 22, 35, 40, 46, 66, 86, 92, 131, 147,

157, 176, 191, 214, 243, 265, 288

MIN(), 15, 191, 214, 243, 265

MINIMAL, 98

MOD, 71

MODIFY, 44

monitor, 86, 92

MRR, 214

MRR_SORTED, 214

msql2mysql, 86

mtr_memo_contains, 98

mtr_memo_note_modifications, 98

MTS, 37, 71, 75, 121, 131, 147, 166, 176, 230

multi-column, 66

multi-source, 50

multiple files, 121

multiple PK columns, 75

multithreaded, 50, 71

multithreaded slave, 20, 22, 35, 44, 50, 54, 66, 176, 243

multi_range_count, 176

mutex, 58, 75, 86, 111

mutex deadlock, 37

mutexes, 176

mutex_spin_wait, 98

MyISAM, 13, 46, 98, 214, 230

myisamchk, 214

myisampack, 230

myisam_sort_buffer_size, 214

myisam_use_mmap, 17, 230

mysql, 279

mysql client, 121, 166

MySQL Enterprise Monitor, 121

mysql-log-rotate, 243

mysql-systemd-start, 50

mysql-test-run.pl, 31

mysql.master_slave_info, 243

mysql.plugin, 8

mysql.slave_master_info, 191

mysql.slave_relay_log_info, 191

mysql.slave_worker_info, 243

mysqlaccess, 20, 86

mysqladmin, 9, 46, 54, 75, 121, 147, 166, 214, 265, 279

mysqladmin status, 214

mysqlbinlog, 20, 31, 37, 54, 63, 66, 71, 75, 92, 98, 121, 131, 147, 176, 191,

214, 230, 243, 265, 279, 288

mysqlbinlog --verbose --verbose, 191

mysqlbinlog --version, 131

mysqlbug, 82

mysqlcheck, 131, 243, 279

mysqld, 66, 105, 121, 214

mysqld options, 157

306

MySQL 5.6 Release Notes

mysqld.1.err, 92

mysqldump, 5, 13, 19, 20, 22, 35, 66, 71, 75, 82, 92, 105, 111, 121, 131,

147, 157, 176, 191, 214, 230, 265, 279, 288

mysqld_multi, 35

mysqld_safe, 5, 22, 27, 31, 131, 166, 191, 214, 230, 243

mysqld_safe.pid, 22

mysqlhotcopy, 75, 176, 214

mysqlimport, 46, 279

mysqlshow, 279

mysqlslap, 50, 191, 243, 265, 288

mysql_affected_rows(), 243

mysql_config, 54, 66, 86, 131

mysql_config_editor, 27, 54, 75, 131, 157, 191

mysql_convert_table_format, 86

mysql_find_rows, 86

mysql_firewall_trace, 54

mysql_fix_extensions, 86

MYSQL_GROUP_SUFFIX, 17

MYSQL_HISTIGNORE, 166

mysql_install_db, 66, 86, 92, 131, 157, 166, 191, 230

mysql_kill(), 157

mysql_list_fields(), 243

mysql_load_plugin(), 147, 243

mysql_load_plugin_v(), 147

mysql_options(), 22, 37, 40, 98

mysql_options() C API function, 191

mysql_options4() C API function, 191

MYSQL_OPT_CAN_HANDLE_EXPIRED_PASSWORDS mysql_options() option, 147

MYSQL_OPT_RECONNECT, 75

mysql_plugin, 92, 166, 230, 243

mysql_real_connect(), 33, 58, 105

mysql_secure_installation, 22, 166, 176

mysql_setpermission, 66, 86

mysql_stmt_close(), 20

mysql_stmt_errno(), 20

mysql_stmt_error(), 20

mysql_stmt_execute(), 40, 191

mysql_stmt_send_long_data(), 243

mysql_stmt_sqlstate(), 20

mysql_stmt_store_result(), 86

mysql_store_result(), 5, 191

mysql_thread_id(), 157

mysql_upgrade, 44, 98, 111, 121, 131, 157, 176, 191, 230, 243

mysql_use_result(), 191

mysql_waitpid, 82

mysql_zap, 82

my_charset_filename, 111

my_load_defaults(), 121

my_print_defaults, 54

m_ordered_rec_buffer, 176

named_pipe_full_access_group, 9, 11

307

MySQL 5.6 Release Notes

NAME_CONST(), 19, 33

NDB Cluster, 15, 191

net_buffer_length, 243

NO_BACKSLASH_ESCAPES, 214

NO_ZERO_DATE, 86, 191

NO_ZERO_IN_DATE, 86, 191

NULL, 12, 19, 121, 147, 214, 243

NULLIF(), 15

NUMA, 44, 46

off-page storage, 82

old_buf_free, 105

old_lsn, 105

OLD_PASSWORD(), 66, 176

old_passwords, 17, 176

online ALTER TABLE, 105, 131

online DDL, 15, 31, 44, 86

ONLINE_INDEX_ABORTED_DROPPED, 63

OpenBSD, 265

OpenSSL, 4, 5, 7, 8, 9, 11, 13, 17, 20, 22, 27, 31, 35, 37, 40,

50, 63, 66, 75, 85, 131, 147, 176, 191

open_files_limit, 111

optimization, 71, 265

OPTIMIZE, 37, 157

OPTIMIZE TABLE, 12, 58, 82, 86, 230, 265

optimizer, 17, 19, 20, 22, 27, 35, 37, 40, 44, 46, 50, 54, 58, 63, 66,

71, 75, 82, 86, 92, 98, 105, 111, 121, 131, 147, 157, 166, 176, 191, 214, 230,

243, 265, 279, 288

optimizer trace, 230

optimizer_search_depth, 288

optimizer_switch, 86, 265, 279

options, 9, 11, 13, 22, 31, 46, 54, 86, 121, 131, 243, 265

OPT_CHECK_ORDER_BY, 111

OR, 7

Oracle Linux, 75

ORDER BY, 5, 17

orphan table, 105

OS X, 46, 214, 243

os-file_pread, 63

os_file_pwrite, 63

os_thread_get_curr_id, 92

OS_THREAD_SLEEP, 121

OUTER JOIN, 265

outer queries, 166

O_DIRECT, 37, 50, 98

packaging, 4, 5, 7, 9, 12, 17, 19, 20, 22, 27, 31, 35, 37, 40, 44,

46, 50, 54, 58, 63, 66, 71, 75, 82, 98, 111, 121, 131, 147, 176, 214, 265

Packaging, 46

page, 66, 71

page cleaner, 71

308

MySQL 5.6 Release Notes

page flushing, 75, 82, 121

page reorganize, 121

page size, 44

pages_free, 131

PAGE_FREE, 166

page_hash lock, 131

page_zip_available, 121

page_zip_decompress, 111

page_zip_validate, 111

parallelism, 111

parent table, 75

parser, 7, 8, 11, 12, 19, 27, 35, 50, 75, 86, 92, 98, 131, 147, 157, 166,

243, 265

partition, 44, 86

PARTITION BY KEY, 166

PARTITION BY KEY ALGORITHM, 131

PARTITION BY LIST, 105

PARTITION BY RANGE, 131

partition ID, 17

partition pruning, 131, 166, 176

partition selection, 214, 265

Partitioning, 5, 9, 17, 19, 37, 46, 50, 54, 58, 63, 66, 71, 75, 86, 92,

98, 105, 111, 121, 131, 147, 157, 166, 176, 191, 214, 230, 243, 265, 288

partitioning, 19

PARTITION_COMMENT, 191

PASSWORD, 230

PASSWORD(), 17, 66, 176

password_expired, 191

performance, 86, 105, 111, 230

Performance, 111, 131, 147, 157, 176, 191, 214, 230, 243, 265

Performance Schema, 12, 13, 17, 19, 22, 27, 33, 35, 37, 40, 44, 46, 50,

54, 58, 66, 75, 86, 92, 98, 105, 111, 121, 131, 147, 157, 166, 176, 191, 214,

230, 243, 265, 279, 288

performance_schema, 191

performance_schema_max_digest_length, 50

perror, 243

persistent statistics, 82, 105

phrase search, 58

pluggable authentication, 19, 22, 37, 58, 66, 121, 131, 147, 230, 265

plugin API, 243

plugin services, 265

plugins, 15, 22, 27, 35, 37, 44, 46, 58, 71, 75, 86, 105, 111, 121, 147,

214, 230, 243

PLUGIN_DIR, 230

plugin_dir, 243

Port, 214

prepared statements, 11, 17, 22, 31, 33, 37, 40, 44, 54, 71, 82, 98, 105,

121, 131, 147, 166, 176, 214, 243

prepare_commit_mutex, 111

Previous_GTIDs_log_event, 121

Previous_gtid_event, 82

primary key, 8, 105, 121

PRIMARY KEY, 166, 191

primary keys, 191, 230

309

MySQL 5.6 Release Notes

printf, 92

priority queue, 92

privileges, 4, 4, 5, 8, 9, 13, 15, 17, 22, 35, 37, 44, 46, 54, 58,

66, 75, 86, 92, 98, 105, 111, 121, 131, 147, 166, 176, 230, 243

procedure, 66

PROCEDURE ANALYSE, 191

PROCEDURE ANALYSE(), 46, 243

PROCESSLIST_STATE, 86

process_arithmetic_command, 58

profiling, 166

profiling_history_size, 166

PROXY, 8, 265

pruning, 111

pseudo-slave mode, 147

purge, 63, 71, 86, 105

PURGE BINARY LOGS, 75, 121

purge thread, 46, 86

push_warning_printf, 63

P_S.threads, 86

Queries per second, 214

query cache, 20, 54, 71, 131, 157, 166, 191, 214

query log events, 147

query performance, 111

query_alloc_block_size, 44

query_cache_min_res_unit, 46

quotation mark, 75

QUOTE(), 22

race condition, 111, 121

RAND(), 191

RANDOM_BYTES(), 86

range, 111

Range checked for each record, 166

raw device, 92

RBR, 27, 66, 71, 75, 105, 121, 131, 176, 191, 230, 265

rbt_search, 66

READ COMMITTED, 46, 71

read-ahead, 279

read-only, 105

read-write lock, 75

readline, 214

readme, 92

read_only, 20

read_rnd_buffer_size, 54

rebuild, 86

REBUILD PARTITION, 98

receiver thread, 54

record format, 214

recovery, 46, 63, 71, 75, 92, 98, 105, 121

recv_writer, 121

310

MySQL 5.6 Release Notes

redo log, 63, 66, 75, 98

redo log scan, 121

refactoring, 111, 176

REGEXP, 50

regression, 111

regular expressions, 50

relay log, 66, 131, 157, 176, 191

relay log index, 166

relay log recovery, 35

relay log rotation, 46, 71, 82

relay logs, 191

relaylog.log_lock, 35

relay_log_basename, 265

RELAY_LOG_FILE, 265

relay_log_info_repository, 86, 105, 147, 176, 265

relay_log_purge, 191

relay_log_recovery, 191

remote connections, 131

RENAME, 58

RENAME TABLE, 15, 92, 121, 131

RENAME USER, 191

REORGANIZE PARTITION, 214

REPAIR TABLE, 82, 157, 176, 243

REPLACE, 15, 37

REPLACE ... SELECT, 214

REPLACE INTO, 46

replace utility, 66

replicate-rewrite-db, 230

Replication, 5, 6, 7, 8, 9, 11, 12, 13, 15, 17, 19, 20, 22, 27, 31,

33, 35, 37, 40, 44, 46, 50, 54, 58, 63, 66, 71, 75, 82, 86, 92, 98,

105, 111, 121, 131, 147, 157, 166, 176, 191, 214, 230, 243, 265, 279, 288

replication, 19

REPLICATION CLIENT privilege, 191

replication filters, 98

replication info tables, 157

repositories, 214

reservation, 54

RESET MASTER, 121

RESET SLAVE, 176, 243, 288

resolve_stack_dump, 44

resource usage, 86, 176

restarts, 63, 121, 191, 214

result cache, 86

Retrieved_Gtid_Set, 46, 147

REVOKE, 98, 166, 191

rollback, 50, 63, 92, 98, 105, 121, 131, 279

ROLLBACK TO SAVEPOINT, 46

ROLLUP, 111, 131, 176

ROUND(), 230

row event corruption, 92

row format, 33, 35

row images, 265

row size, 63

row-based, 27

311

MySQL 5.6 Release Notes

row0log.cc, 105

Rows_query_log_events, 191

ROW_FORMAT, 58, 105, 191

row_merge_read_clustered_index, 131

row_upd_changes_ord_field_binary, 86

row_vers_impl_x_locked_lowx, 86

RPAD(), 71, 191

rpl_recover_rank, 288

rpl_semi_sync_master_enabled, 98

rpl_semi_sync_master_timeout, 111

rpl_semi_sync_master_wait_no_slave, 98

Rpl_semi_sync_master_yes_tx, 92

Rpl_status, 288

rpl_stop_slave_timeout, 111

rpl_tblmap.cc, 111

RPM, 147

rw_lock_x_lock_func_nowait, 92

sandbox mode, 147

savepoint, 58, 98

SBR, 121, 191, 214, 230, 243

scalability, 92

scans, 157

schema mismatch, 44, 50

scientific notation, 6

scope, 66

secondary index, 71, 86, 111

Seconds_Behind_Master, 63, 92, 157

secure_auth, 176, 214

secure_file_priv, 31

security, 9, 11

Security Enhancement, 230

Security Fix, 243, 265, 288

SEC_TO_TIME(), 131

segmentation fault, 66, 86, 92

SELECT, 6, 11, 111, 176, 214, 265

SELECT ... FOR UPDATE, 265

semaphore wait, 121

semijoins, 191

semisynchronous replication, 27, 54, 71, 75, 86, 105, 121, 147, 191

semisynchronous replication plugin, 92

server activity counter, 71

server ID, 92

server options, 288

server startup timeout, 121

server variables, 157

server version, 131

server_uuid, 33, 71, 288

set, 54, 58, 111

SET, 131

SET OPTION, 191

SET PASSWORD, 98

312

MySQL 5.6 Release Notes

SET TRANSACTION, 214

SET type, 121

set-gtid-purged, 121

SHA1(), 191

sha256_password, 17, 19, 176

SHOW AUTHORS, 166

SHOW BINARY LOGS statement, 191

SHOW BINLOG EVENTS, 191

SHOW COLUMNS, 131

SHOW CONTRIBUTORS, 166

SHOW CREATE DATABASE, 279

SHOW CREATE TABLE, 131

SHOW CREATE TRIGGER, 265

SHOW ENGINE INNODB STATUS, 27, 54, 92, 98

SHOW EVENTS, 243

SHOW INDEX, 105

SHOW MASTER LOGS statement, 191

SHOW NEW MASTER, 265

SHOW PRIVILEGES, 265

SHOW PROCESSLIST, 75, 230

SHOW PROFILE, 157, 176, 265

SHOW PROFILES, 176

SHOW SLAVE HOSTS, 214

SHOW SLAVE STATUS, 46, 86, 92, 111, 147, 157, 191, 243, 279, 288

SHOW STATUS, 50, 121, 243, 265

SHOW TABLE STATUS, 82

SHOW TABLES, 191

SHOW VARIABLES, 131

SHOW WARNINGS, 243

show_old_temporals, 58

shutdown, 46, 50, 54, 58, 66, 86, 92, 105, 147

shutdown hang, 111

shutdown timeout, 121

SIGHUP, 82, 214

signal, 54

SIGPIPE, 191

skip-slave-start, 105

skipped events, 46

slave, 33

slave connections, 131

slave error, 58

slave I/O thread, 157

slave log tables, 191

slave options, 131

slave reconnection, 121

slave SQL thread, 86, 157

slave-skip-errors, 243

slave_allow_batching, 191

slave_master_info, 121, 176, 243, 265

slave_max_allowed_packet, 121, 191

slave_net_timeout, 147

Slave_open_temp_tables, 82

slave_parallel_workers, 86, 105, 176, 191, 230, 243

slave_pending_jobs_size_max, 20, 121

313

MySQL 5.6 Release Notes

slave_relay_log_info, 121, 176, 243, 265

slave_rows_search_algorithms, 131, 191

slave_transaction_retries, 243

slave_type_conversions, 111

slave_worker_info table, 176

slow shutdown, 63

slow_query_log, 191

Solaris, 86, 131, 157, 176

sort buffer, 40

sorting, 92

sort_buffer_length, 4

space character, 166

space ID, 75

SPACE(), 230

spatial functions, 243

SQL functions, 157

sql/sql_base.cc, 75

SQL_AFTER_GTIDS, 105, 191

SQL_AFTER_MTS_GAPS, 191

SQL_BEFORE_GTIDS, 191

SQL_BUFFER_RESULT, 176

sql_log_bin, 66

sql_mode, 86

sql_slave_skip_counter, 147

SQL_THREAD_WAIT_AFTER_GTIDS(), 166, 176

srv_file_check_mode, 92

SRV_FORCE_NO_TRX_UNDO, 98

srv_master_thread, 105

srv_max_n_threads, 98

srv_read_only_mode, 131

SSH, 230

SSL, 4, 5, 7, 9, 11, 13, 17, 20, 22, 27, 31, 35, 37, 40, 46, 63,

71, 176, 243

Ssl_cipher_list, 243

Ssl_server_not_after, 243

Ssl_server_not_before, 243

Ssl_verify_server_cert, 243

stack size, 22

stall, 37

standard monitor, 92

START SLAVE, 82, 105, 131, 147, 176, 191, 214, 230, 288

START SLAVE IO_THREAD, 98

START SLAVE UNTIL, 105, 191

START TRANSACTION, 4, 105, 214

startup, 40, 75, 92, 214

Start_log_event_v3, 66

start_time, 92

statistics, 22, 27, 82, 111

status variables, 131, 288

STOP SLAVE, 37, 82, 98, 131, 176, 191, 214, 265, 279, 288

STOP SLAVE IO_THREAD, 98

storage engine initailization, 7

storage engines, 75, 166, 191, 214, 243

stored functions, 214

314

MySQL 5.6 Release Notes

stored procedures, 40, 46, 54, 82, 105, 121, 131, 214, 243

stored program, 82

stored programs, 6, 15, 17, 31, 35, 147, 157, 166, 176, 191, 214, 230, 243

stored routines, 105, 147, 157, 166, 214

stored_program_cache, 214

STRAIGHT_JOIN, 214

strict mode, 54

ST_Contains(), 166, 176

ST_Difference(), 166

ST_Equals(), 166

ST_Within(), 166

subpartitions, 46, 214

subqueries, 4, 11, 12, 15, 214, 279

SUBSTRING_INDEX(), 214

SUPER privilege, 191

symbolic links, 157

sync, 71

sync_array_cell_print, 131

sync_binlog, 86

system tables, 157

system tablespace, 44, 86

system variables, 288

SYS_DATAFILES, 92

SYS_INDEXES, 66

SYS_TABLES, 58

table, 63

table cache, 63

table handler, 105

table lock, 35

table map events, 243

Table Monitor, 82

table monitor, 92

table name, 46

table statistics, 92

TABLE::key_info, 131

tablespace, 63, 66, 92, 105, 111, 121

tablespace files, 37

tablespace import, 6, 15

tablespace monitor, 92

table_open_cache, 191

Table_open_cache_hits, 191

table_open_cache_instances, 191

Table_open_cache_misses, 191

Table_open_cache_overflows, 191

TABLE_ROWS, 82

tcmalloc, 5, 35

temporary files, 71

temporary tables, 33, 40, 58, 66, 75, 92, 147, 176, 214, 243, 279

test suite, 20, 33, 37, 54, 63, 191

thread cache, 166

thread concurrency, 111

315

MySQL 5.6 Release Notes

thread locking, 75

thread pool plugin, 15, 22, 98, 105, 111, 131

thread stack overflow, 121

threadpool plugin, 58

Threads_running, 176

thread_concurrency, 71, 279

thread_pool_high_priority_connection, 121

timed_mutexes, 75

timeouts, 166

TIMESTAMP, 75, 131, 191, 214, 265

TLS, 230

tmpdir, 40, 86

tmpfs, 98

token size, 40

TO_BASE64(), 279

TO_DAYS(), 131

transaction log, 98

transactional tables, 46

transactions, 19, 71, 75, 82, 86, 111, 147, 166, 176, 191, 214, 243, 279

transaction_prealloc_size, 58

transportable tablespace, 13

triggers, 46, 75, 82, 214, 243

TRUNCATE, 58, 63

TRUNCATE TABLE, 50, 82, 92, 98, 111

trx->fts_trx, 98

trx_free_for_background(), 121

trx_rollback_or_clean_recovered(), 121

trx_rollback_resurrected(), 121

type conversions, 147

types, 265

UBSAN, 22

ucs2_unicode_520_ci, 176

udf_example, 9

ULN, 147

UMASK, 157

undo log, 17, 105

undo tablespace, 22, 105

Unicode, 265, 279

uninstall, 86

UNION, 11, 13, 82, 131, 147, 265

unique, 12

UNIQUE INDEX LOCK, 121

unique keys, 191

unique secondary index, 71

UNIV_DEBUG, 121

UNIV_LOG_DEBUG, 105

UNIV_SYNC_DEBUG, 92, 121

UNIX_TIMESTAMP(), 243

unsafe statements, 214

unsigned_flag, 288

UPDATE, 63, 86, 243, 265

316

MySQL 5.6 Release Notes

updates, 121

UpdateXML(), 8, 147, 176, 279

Update_rows_log_event, 121

UPDATE_TIME, 54

upgrades, 63, 82, 92, 147, 176, 191, 214

upgrades and downgrades, 131

uppercase, 66

USE, 166, 265

USER, 230

user variables, 121, 131, 191

user-defined variables, 176

username, 166

UTF-16LE, 279

UTF-8, 58

UTF-8 table name, 111

utf16le, 279

UTF8, 13

UUIDs, 33, 147, 288

Valgrind, 6, 40, 44, 111, 121, 131, 147, 157, 176, 191, 214, 230, 243, 265

validate_password plugin, 46, 50, 66, 121, 147

validate_password_dictionary_file, 50, 147

validate_password_dictionary_file_last_parsed, 50

validate_password_dictionary_file_words_count, 50

VALIDATE_PASSWORD_STRENGTH(), 176

VALUES IN (NULL), 105

VALUES(), 121, 131

VARCHAR, 214

variable scope, 131

variables, 111

versions, 86, 131

version_compile_machine, 166, 191

views, 46, 75, 92, 121, 131, 147, 166, 176, 191, 214, 243, 279

Visual C++ Redistributable, 22

Visual Studio, 86

Warning 1292, 214

warnings, 86, 166, 176, 214, 230

WEEK, 265

WEIGHT_STRING(), 176, 288

WHERE, 111

WHERE_CONDITION optimization, 4

whitespace, 20

WITH CONSISTENT SNAPSHOT, 105

Within(), 176

WITH_LIBWRAP, 131

WITH_SSL, 166, 176, 191

worker threads, 111

write locks, 54, 58

317

MySQL 5.6 Release Notes

x86_64, 288

XA, 63, 121, 131, 176, 243

XA COMMIT, 243

XA PREPARE, 54

XA transactions, 191, 243

XML, 22, 92, 98, 147, 176, 265

XML functions, 37

XPath, 92, 147

yaSSL, 7, 19, 31, 40, 46, 54, 63, 66, 71, 86, 131, 147, 191

YEAR, 191

zip_mutex, 86

zlib, 12, 243

318