MySQL是最受欢迎的开源SQL数据库管理系统，它由MySQL AB开发、发布和支持。MySQL AB是一家基于MySQL开发人员的商业公司，它是一家使 用了一种成功的商业模式来结合开源价值和方法论的第二代开源公司。MySQL是MySQL AB的注册商标。
该版本主要是 bug 修复，详情请看 Change History
Changes in MySQL 5.5.23 (Not yet released)
Functionality Added or Changed
MySQL-shared-compatRPM package enables users of Red Hat-privided
mysql-*-5.1RPM packages to migrate to Oracle-provided
MySQL-shared-compatnow replaces the Red Hat
mysql-libspackage by replacing
libmysqlclient.sofiles 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)
- Security Fix: Bug #59533 was fixed.
- Performance: Partitioning: InnoDB Storage Engine: The statistics used by the optimizer for queries against partitioned
InnoDBtables 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 TABLEstatement for
InnoDBtables, especially on systems with a large buffer pool. The fix speeds up the processing for freeing entries in theadaptive hash index. (Bug #13704145, Bug #64284)
- InnoDB Storage Engine: Deleting a huge amount of data from
InnoDBtables 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 #13847885)
- InnoDB Storage Engine: If the server crashed during a
CREATE INDEXstatement for an
InnoDBtable, or a
DROP DATABASEstatement for a database containing
InnoDBtables, an index could be corrupted, causing an error message when accessing the table after restart:
InnoDB: Error: trying to load index
table_nameInnoDB: 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 #11766019)
- InnoDB Storage Engine: When data was removed from an
InnoDBtable, newly inserted data might not reuse the freed disk blocks, leading to an unexpected size increase for the system tablespace or
.ibdfile (depending on the setting of
OPTIMIZE TABLEcould compact a
.ibdfile 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
SELECTissued in a new transaction. (Bug #11761296, Bug #53775)
- Replication: Formerly, the default value shown for the
Portcolumn in the output of
SHOW SLAVE HOSTSwas 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-portserver option. (Bug #13333431)
- Replication: The
--relay-log-space-limitoption was sometimes ignored.
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 #13898343)
- Incorrect stored program caching could cause statements within a stored program that included a
GROUP BYclause to return different results across multiple program invocations. (Bug #13805127)
- Mishandling of
NO_BACKSLASH_ESCAPESSQL mode within stored procedures on slave servers could cause replication failures. (Bug #12601974)
SAVEPOINTstatements 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 #13417446)
SHOWstatements treated stored procedure, stored function, and event names as case sensitive. (Bug #56224, Bug #11763507)