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MySQL 5.6 Release Notes  /  Changes in MySQL 5.6.31 (2016-06-02, General Availability)

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

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  • The INSTALL-SOURCE file had partly outdated information and has been removed from source packages.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

    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 are tagged with symver 16 in, 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)

  • 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.

  • 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)