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MySQL Community Server 5.5.19 has been released
Posted by: Bjorn Munch
Date: December 08, 2011 09:18AM

Dear MySQL users,

MySQL 5.5.19 is a new version of the 5.5 production release of the
world's most popular open source database. MySQL 5.5.19 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 5.5.19 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 5.5.19 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 5.5.19 (8 December 2011)

   Functionality Added or Changed

     * Performance of metadata locking operations on Windows XP
       systems was improved by instituting a cache for metadata lock
       objects. This permits the server to avoid expensive operations
       for creation and destruction of synchronization objects on XP.
       A new system variable, metadata_locks_cache_size, permits
       control over the size of the cache. The default size is 1024.
       (Bug #12695572)

   Bugs Fixed

     * Rounding DBL_MAX returned DBL_MAX, not 'inf'. (Bug #13261955)

     * mysql_upgrade did not upgrade the system tables or create the
       mysql_upgrade_info file when run with the --write-binlog or
       --skip-write-binlog option. (Bug #60223, Bug #11827359)

     * If a plugin was uninstalled, thread local variables for plugin
       variables of string type with wth PLUGIN_VAR_MEMALLOC flag
       were not freed. (Bug #56652, Bug #11763882)

     * Deadlock could occur when these four things happened at the
       same time: 1) An old dump thread was waiting for the binary
       log to grow. 2) The slave server that replicates from the old
       dump thread tried to reconnect. During reconnection, the new
       dump thread tried to kill the old dump thread. 3) A KILL
       statement tried to kill the old dump thread. 4) An INSERT
       statement caused a binary log rotation. (Bug #56299, Bug

Bjorn Munch
MySQL/ORACLE Release Engineering Team

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MySQL Community Server 5.5.19 has been released
December 08, 2011 09:18AM

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