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5.2.10 Changes in MySQL 5.1.23 (29 January 2008) »
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5.2.9. Changes in MySQL 5.1.28 (28 August 2008)

Bugs fixed:

  • Performance: Incompatible Change: Some performance problems of SHOW ENGINE INNODB STATUS were reduced by removing used cells and Total number of lock structs in row lock hash table from the output. Now these values are present only if the UNIV_DEBUG symbol is defined at MySQL build time. (Bug#36941, Bug#36942)

  • Important Change: Security Fix: Additional corrections were made for the symlink-related privilege problem originally addressed in MySQL 5.1.24. The original fix did not correctly handle the data directory path name if it contained symlinked directories in its path, and the check was made only at table-creation time, not at table-opening time later.

    Note

    Additional fixes were made in MySQL 5.1.41.

    (Bug#32167, CVE-2008-2079)

    See also Bug#39277.

  • Incompatible Change: There were some problems using DllMain() hook functions on Windows that automatically do global and per-thread initialization for libmysqld.dll:

    • Per-thread initialization: MySQL internally counts the number of active threads, which causes a delay in my_end() if not all threads have exited. But there are threads that can be started either by Windows internally (often in TCP/IP scenarios) or by users. Those threads do not necessarily use libmysql.dll functionality but still contribute to the open-thread count. (One symptom is a five-second delay in times for PHP scripts to finish.)

    • Process-initialization: my_init() calls WSAStartup that itself loads DLLs and can lead to a deadlock in the Windows loader.

    To correct these problems, DLL initialization code now is not invoked from libmysql.dll by default. To obtain the previous behavior (DLL initialization code will be called), set the LIBMYSQL_DLLINIT environment variable to any value. This variable exists only to prevent breakage of existing Windows-only applications that do not call mysql_thread_init() and work okay today. Use of LIBMYSQL_DLLINIT is discouraged and is removed in MySQL 6.0. (Bug#37226, Bug#33031)

  • Incompatible Change: SHOW STATUS took a lot of CPU time for calculating the value of the Innodb_buffer_pool_pages_latched status variable. Now this variable is calculated and included in the output of SHOW STATUS only if the UNIV_DEBUG symbol is defined at MySQL build time. (Bug#36600)

  • Incompatible Change: An additional correction to the original MySQL 5.1.23 fix was made to normalize directory names before adding them to the list of directories. This prevents /etc/ and /etc from being considered different, for example. (Bug#20748)

    See also Bug#38180.