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MySQL 5.6 Release Notes  /  Changes in MySQL 5.6.39 (2018-01-15, General Availability)

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

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

    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documentation, available at The related Unix man pages that previously were produced from the old test suite manual are no longer updated and have gone out of date.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)

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

  • A circular dependency problem involving sql/ 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)