MySQL 5.6.20 was recently released (it is the latest MySQL 5.6, is GA), and is available for download here.
For this release, there is 1 “Security Fix”, 1 “InnoDB Important Change”, and 7 “Functionality Added or Changed” fixes, all of which should be read in case they might affect you (though for this release, these mostly appear to be minor – some [default] changes, build notes/changes, and deprecations):
- Security Fix: 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.
- InnoDB 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, innodb_log_file_size should be set to a value greater than 10 times 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). Failing to do so could result in “Row size too large” errors. No action is required if your innodb_log_file_size setting is already sufficiently large or your tables contain no BLOB data. (Bug #69477)
- Replication: The new system variable binlog_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 binlog_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)
- CMake support was updated to handle CMake version 3.
- 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.
- Support for LinuxThreads has been removed from the source code. LinuxThreads was superseded by NPTL in Linux 2.6. (Bug #72888)
- 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)
- The mysqlhotcopy utility is now deprecated and will be removed in a future version of MySQL. 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.
- The timed_mutexes system variable has no effect and is deprecated.
In addition to those, there were 52 other bug fixes:
- 11 InnoDB
- 09 Replication
- 01 Partitioning
- 31 Miscellaneous
There were 2 regression bugs fixed, so check if they might have affected you:
- 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.
- 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.
I’ve not too much to say about this release regarding whether one should upgrade or not. I will say that if you are running a *Commercial* version of MySQL 5.6, pre-5.6.20, and you use SSL, then you should upgrade. Aside from that, it more depends if you’re affected by one of these bugs or not.
The full 5.6.20 changelogs can be viewed here (which has more details about all of the bugs listed above):
Hope this helps.