Dear MySQL users, MySQL 5.5.25a is a new version of the 5.5 production release of the world's most popular open source database. MySQL 5.5.25a is recommended for use on production systems.
MySQL 5.5.25a is a replacement of MySQL 5.5.25, in that version a regression bug was detected in the optimizer (Bug #65745). Because of this, MySQL 5.5.25 has been removed from the download sites. We recommend that users who have installed MySQL 5.5.25 upgrade to MySQL 5.5.25a at the earliest opportunity. That bug is specific to MySQL 5.5.25, other versions are not affected. MySQL 5.5 includes several high-impact enhancements to improve the performance and scalability of the MySQL Database, taking advantage of the latest multi-CPU and multi-core hardware and operating systems. In addition, with release 5.5, InnoDB is now the default storage engine for the MySQL Database, delivering ACID transactions, referential integrity and crash recovery by default. MySQL 5.5 also provides a number of additional enhancements including: - Significantly improved performance on Windows, with various Windows specific features and improvements - Higher availability, with new semi-synchronous replication and Replication Heart Beat - Improved usability, with Improved index and table partitioning, SIGNAL/RESIGNAL support and enhanced diagnostics, including a new Performance Schema monitoring capability. For a more complete look at what's new in MySQL 5.5, please see the following resources: MySQL 5.5 is GA, Interview with Tomas Ulin: http://dev.mysql.com/tech-resources/interviews/thomas-ulin-mysql-55.html Documentation: http://dev.mysql.com/doc/refman/5.5/en/mysql-nutshell.html Whitepaper: What's New in MySQL 5.5: http://dev.mysql.com/why-mysql/white-papers/mysql-wp-whatsnew-mysql-55.php If you are running a MySQL production level system, we would like to direct your attention to MySQL Enterprise Edition, which includes the most comprehensive set of MySQL production, backup, monitoring, modeling, development, and administration tools so businesses can achieve the highest levels of MySQL performance, security and uptime. http://mysql.com/products/enterprise/ For information on installing MySQL 5.5.25a on new servers, please see the MySQL installation documentation at http://dev.mysql.com/doc/refman/5.5/en/installing.html For upgrading from previous MySQL releases, please see the important upgrade considerations at: http://dev.mysql.com/doc/refman/5.5/en/upgrading.html MySQL Database 5.5.25a is available in source and binary form for a number of platforms from our download pages at: http://dev.mysql.com/downloads/mysql/ Not all mirror sites may be up to date at this point in time, so if you can't find this version on some mirror, please try again later or choose another download site. We welcome and appreciate your feedback, bug reports, bug fixes, patches, etc.: http://forge.mysql.com/wiki/Contributing The following sections list the changes in the MySQL source code since the previous released versions, MySQL 5.5.25 (withdrawn) and MySQL 5.5.24. They may also be viewed online at: http://dev.mysql.com/doc/refman/5.5/en/news-5-5-25a.html http://dev.mysql.com/doc/refman/5.5/en/news-5-5-25.html Enjoy! D.1.2. Changes in MySQL 5.5.25a (2012-July-05) Note Due to MSI restrictions, the MSI packages of MySQL 5.5.25a will treat the version as 5.5.26 internally; for example, as displayed by the Installation Wizard. MySQL itself reports the version as 5.5.25a; for example, if you check the value of the VERSION() SQL function or the version system variable. Bugs Fixed * A regression bug in the optimizer could cause excessive disk usage for UPDATE statements. (Bug #65745, Bug #14248833) D.1.3. Changes in MySQL 5.5.25 (2012-May-30) Note MySQL 5.5.25 is superseded by MySQL 5.5.25a due to a regression bug that can cause excessive disk usage (for details, see Bug #65745). Current users of 5.5.25: Monitor disk usage and upgrade to 5.5.25a as soon as that is made available. Users contemplating upgrades to 5.5.25: Defer and upgrade to 5.5.25a instead when that is made available. Functionality Added or Changed * 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.) * The --safe-mode server option now is deprecated and will be removed in MySQL 5.6. Bugs Fixed * 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) * 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 Section 14.3.9.2, "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: The Innodb_buffer_pool_pages_flushed status variable was incorrectly set to twice the value it should be. Its value should never exceed the value of Innodb_pages_written. (Bug #14000361, Bug #65030) * 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: 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) * 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: 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 Section 16.2.3, "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 when using the STATEMENT binary logging format. For more information, see Section 16.1.2.3, "Determination of Safe and Unsafe Statements in Binary Logging," as well as Section 16.4.1.1, "Replication and AUTO_INCREMENT." Note Tables using the InnoDB storage engine are not affected by this issue, since InnoDB does not allow the creation of a composite key that includes an AUTO_INCREMENT column, where this column is not the first column in the key. (Bug #11754117, Bug #45670) References: See also Bug #11761686, Bug #54201, Bug #11746146, Bug #23894. * SHOW TABLES was very slow unless the required information was already in the disk cache. (Bug #60961, Bug #12427262) On behalf of the MySQL Build Team, Sunanda Menon -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql