D.1.6. Changes in MySQL 5.5.4 (09 April 2010)

InnoDB Notes:

Functionality added or changed:

  • InnoDB Storage Engine: InnoDB now has a innodb_use_native_aio system variable that can be disabled at startup if there is a problem with the asynchronous I/O subsystem in the OS. This variable applies to Linux systems only, where the MySQL server now has a dependency on the libaio library.

Bugs fixed:

  • Performance: InnoDB Storage Engine: The redo scan during InnoDB recovery used excessive CPU. The efficiency of this scan was improved, significantly speeding up crash recovery. (Bug#49535, Bug#29847)

  • Performance: InnoDB Storage Engine: InnoDB page-freeing operations were made faster for compressed blocks, speeding up ALTER TABLE, DROP TABLE, and other operations on compressed tables that free compressed blocks. One symptom of the older behavior could be 100% CPU use during these operations. (Bug#35077)

  • InnoDB Storage Engine: The AIX implementation of readdir_r() caused InnoDB errors. (Bug#50691)

  • InnoDB Storage Engine: The limit of 1023 concurrent data-modifying transactions has been raised. The limit is now 128 * 1023 concurrent transactions that generate undo records. You can remove any workarounds that require changing the proper structure of your transactions, such as committing more frequently or delaying DML operations to the end of a transaction. See Section, “Better Scalability with Multiple Rollback Segments”. (Bug#26590)

  • A unique index on a column prefix could not be upgraded to a primary index even if there was no primary index already defined. (Bug#51378)

  • InnoDB did not reset table AUTO_INCREMENT values to the last used values after a server restart. (Bug#49032)

  • When using the EXAMPLE storage engine, when the engine had been built as a plugin (instead of built-in), and DTrace probes had been enabled during the build, loading the storage engine library would fail due to a missing object table entry.

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