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From:Hery Ramilison Date:February 21 2012 5:35am
Subject:MySQL Community Server 5.5.21 has been released
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Dear MySQL users,

MySQL 5.5.21 is a new version of the 5.5 production release of the
world's most popular open source database. MySQL 5.5.21 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 5.5.21 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 5.5.21 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 5.5.21 (17 February 2012)

Functionality Added or Changed

   * A new CMake option, MYSQL_PROJECT_NAME, can be set on Windows
     or Mac OS X to be used in the project name. (Bug #13551687)

Bugs Fixed

   * Performance: InnoDB Storage Engine: Memory allocation for
     InnoDB tables was reorganized to reduce the memory overhead
     for large numbers of tables or partitions, avoiding situations
     where the "resident set size" could grow regardless of FLUSH
     TABLES statements. The problem was most evident for tables
     with large row size. Some of the memory that was formerly
     allocated for every open table is now allocated only when the
     table is modified for the first time. (Bug #11764622, Bug

   * Incompatible Change: An earlier change (in MySQL 5.1.59 and
     5.5.16) was found to modify date-handling behavior in General
     Availability-status series (MySQL 5.1 and 5.5). This change
     has been reverted.
     The change was that several functions became more strict when
     passed a DATE() function value as their argument, thus they
     rejected incomplete dates with a day part of zero. These
     functions were affected: CONVERT_TZ(), DATE_ADD(), DATE_SUB(),
     previous behavior has been restored. (Bug #13458237)

   * InnoDB Storage Engine: A Valgrind error was fixed in the
     function os_aio_init(). (Bug #13612811)

   * InnoDB Storage Engine: The server could crash when creating an
     InnoDB temporary table under Linux, if the $TMPDIR setting
     points to a tmpfs filesystem and innodb_use_native_aio is
     enabled, as it is by default in MySQL 5.5.4 and higher. The
     entry in the error log looked like:
       101123  2:10:59  InnoDB: Operating system error number
                                22 in a file operation.
       InnoDB: Error number 22 means 'Invalid argument'.
     The crash occurred because asynchronous I/O is not supported
     on tmpfs in some Linux kernel versions. The workaround was to
     turn off the innodb_use_native_aio setting or use a different
     temporary directory. The fix causes InnoDB to turn off the
     innodb_use_native_aio setting automatically if it detects that
     the temporary file directory does not support asynchronous
     I/O. (Bug #13593888, Bug #11765450, Bug #58421)

   * InnoDB Storage Engine: References to C preprocessor symbols
     and macros HAVE_purify, UNIV_INIT_MEM_TO_ZERO, and
     UNIV_SET_MEM_TO_ZERO were removed from the InnoDB source code.
     They were only used in debug builds instrumented for Valgrind.
     They are replaced by calls to the UNIV_MEM_INVALID() macro.
     (Bug #13418934)

   * InnoDB Storage Engine: The MySQL server could halt with an
     assertion error:
       InnoDB: Failing assertion: page_get_n_recs(page) > 1
     Subsequent restarts could fail with the same error. The error
     occurred during a purge
     ge) operation involving the InnoDB change buffer
     nge_buffer). The workaround was to set the configuration
     option innodb_change_buffering=inserts. (Bug #13413535, Bug

   * InnoDB Storage Engine: With 1024 InnoDB transactions running
     concurrently and the innodb_file_per_table setting enabled,
     a CREATE TABLE operation for an InnoDB table could fail. The
     .ibd file from the failed CREATE TABLE was left behind,
     preventing the table from being created later, after the load
     had dropped.
     The fix adds error handling to delete the erroneous .ibd file.
     This error was less likely to occur in MySQL 5.5 and 5.6,
     because raising the number of InnoDB undo slots increased the
     number of simultaneous transactions needed to trigger the bug,
     from 1K to 128K. (Bug #12400341)

   * Replication: Executing mysqlbinlog with the --start-position=N
     option, where N was equal either to 0 or to a value greater
     than the length of the dump file, caused it to crash.
     This issue was introduced in MySQL 5.5.18 by the fix for Bug
     #32228 and Bug #11747416. (Bug #13593869, Bug #64035)

   * Replication: On Windows replication slave hosts, STOP SLAVE
     took an excessive length of time to complete when the master
     was down. (Bug #11752315, Bug #43460)

   * A query that used an index on a CHAR column referenced in a
     BETWEEN clause could return invalid results. (Bug #13463488,
     Bug #63437)

   * Expressions that compared a BIGINT column with any non-integer
     constant were performed using integers rather than decimal or
     float values, with the result that the constant could be
     truncated. This could lead to any such comparison that used <,
     >, <=, >=, =, !=/<>, IN, or BETWEEN yielding false positive or
     negative results. (Bug #13463415, Bug #11758543, Bug #63502,
     Bug #50756)

   * When the optimizer performed conversion of DECIMAL values
     while evaluating range conditions, it could produce incorrect
     results. (Bug #13453382)

   * When running mysqldump with both the --single-transaction and
     --flush-logs options, the flushing of the log performed an
     implicit COMMIT (see Section 12.3.3, "Statements That Cause an
     Implicit Commit"), causing more than one transaction to be
     used and thus breaking consistency. (Bug #12809202, Bug

   * It was possible in the event of successive failures for
     mysqld_safe to restart quickly enough to consume excessive
     amounts of CPU. Now, on systems that support the sleep and
     date system utilities, mysqld_safe checks to see whether it
     has restarted more than 5 times in the current second, and if
     so, waits 1 second before attempting another restart. (Bug
     #11761530, Bug #54035)

   * When used with the --xml option, mysqldump --routines failed
     to dump any stored routines, triggers, or events. (Bug
     #11760384, Bug #52792)

   * It was possible on replication slaves where FEDERATED tables
     were in use to get timeouts on long-running operations, such
     as Error 1160 Got an error writing communication packets. The
     FEDERATED tables did not need to be replicated for the issue
     to occur. (Bug #11758931, Bug #51196)
     References: See also Bug #12896628, Bug #61790.

   * If an attempt to initiate a statement failed, the issue could
     not be reported to the client because it was not prepared to
     receive any error messages prior to the execution of any
     statement. Since the user could not execute any queries, they
     were simply disconnected without providing a clear error.
     After the fix for this issue, the client is prepared for an
     error as soon as it attempts to initiate a statement, so that
     the error can be reported prior to disconnecting the user.
     (Bug #11755281, Bug #47032)

   * Using myisamchk with the sort recover method to repair a table
     having fixed-width row format could cause the row pointer size
     to be reduced, effectively resulting in a smaller maximum data
     file size. (Bug #48848, Bug #11756869)

   * On Windows, the server incorrectly constructed the full path
     name of the plugin binary for INSTALL PLUGIN and CREATE
     FUNCTION ... SONAME. (Bug #45549, Bug #11754014)

   * The stored routine cache was subject to a small memory leak
     that over time or with many routines being used could result
     in out-of-memory errors. (Bug #44585, Bug #11753187)

On behalf of the MySQL Build Team,

Hery Ramilison
MySQL/ORACLE Release Engineering Team

MySQL Community Server 5.5.21 has been releasedHery Ramilison21 Feb