Dear MySQL users,


MySQL 5.5.25 is a new version of the 5.5 production release of the
world's most popular open source database. MySQL 5.5.25 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:
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 5.5.25 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 5.5.25 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 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:
http://dev.mysql.com/doc/refman/5.5/en/news-5-5-25.html

Enjoy!

On behalf of the MySQL Build Team,
Joerg Bruehe



D.1.2. Changes in MySQL 5.5.25 (2012-May-30)

Functionality Added or Changed

* 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)


--
Joerg Bruehe, MySQL Build Team, joerg.bruehe@oracle.com
ORACLE Deutschland B.V. & Co. KG, Komturstrasse 18a, D-12099 Berlin
Geschaeftsfuehrer: Juergen Kunz Amtsgericht Muenchen: HRA 95603
Komplementaerin: ORACLE Deutschland Verwaltung B.V. Utrecht, Niederlande
Geschaeftsfuehrer: Alexander van der Ven, Astrid Kepper, Val Maher


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