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From:Hery Ramilison Date:April 13 2012 4:24pm
Subject:MySQL Community Server 5.5.23 has been released
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Dear MySQL users,

MySQL 5.5.23 is a new version of the 5.5 production release of the
world's most popular open source database. MySQL 5.5.23 is recommended
for use on production systems.

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:


Whitepaper: What's New in MySQL 5.5:

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.

For information on installing MySQL 5.5.23 on new servers, please see
the MySQL installation documentation at

For upgrading from previous MySQL releases, please see the important
upgrade considerations at:

MySQL Database 5.5.23 is available in source and binary form for a
number of platforms from our download pages at:

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.:

The following section lists the changes in the MySQL source code since
the previous released version of MySQL 5.5. It may also be viewed
online at:


Changes in MySQL 5.5.23 (12 April 2012)

Functionality Added or Changed

   * The MySQL-shared-compat RPM package enables users of Red
     Hat-privided 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 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)

Bugs Fixed

   * Security Fix: Bug #59533 was fixed.

   * Performance: Partitioning: InnoDB Storage Engine: 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 bug was introduced by Bug #11756867.

   * Performance: InnoDB Storage Engine: Improved the performance
     of the DROP TABLE statement for InnoDB tables, especially on
     systems with a large buffer pool. The fix speeds up the
     processing for freeing entries in the adaptive hash index.
     (Bug #13704145, Bug #64284)

   * InnoDB Storage Engine: Deleting a huge amount of data from
     InnoDB tables within a short time could cause the purge
     operation that flushes data from the buffer pool to stall. If
     this issue occurs, restart the server to work around it. This
     issue is only likely to occur on 32-bit platforms. (Bug

   * InnoDB Storage Engine: 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
      InnoDB: table_name 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

   * InnoDB Storage Engine: 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)

   * Partitioning: After updating a row of a partitioned table and
     selecting that row within the same transaction with the query
     cache enabled, then performing a ROLLBACK, the same result was
     returned by an identical SELECT issued in a new transaction.
     (Bug #11761296, Bug #53775)

   * 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, 0 is used as the default. This change
     also affects the default used for the --report-port server
     option. (Bug #13333431)

   * Replication: The --relay-log-space-limit option was sometimes
     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.

   * An infinite thread loop could develop within Performance
     Schema, causing the server to become unresponsive. (Bug

   * 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

   * Mishandling of NO_BACKSLASH_ESCAPES SQL mode within stored
     procedures on slave servers could cause replication failures.
     (Bug #12601974)

   * SAVEPOINT statements were incorrectly disallowed within XA
     transactions. (Bug #64374, Bug #13737343)
     References: See also Bug #11766752.

   * The Performance Schema incorrectly displayed some backslashes
     in Windows file names (by doubling them). (Bug #63339, Bug

   * SHOW statements treated stored procedure, stored function, and
     event names as case sensitive. (Bug #56224, Bug #11763507)

On behalf of the MySQL Build Team,

Hery Ramilison
MySQL/ORACLE Release Engineering Team
MySQL Community Server 5.5.23 has been releasedHery Ramilison13 Apr