# Functionality added or changed:

* Support for the IBMDB2I storage engine has been removed.
* The pstack library was nonfunctional and has been removed, along with the --with-pstack option for configure. The --enable-pstack option for mysqld is deprecated and will be removed in MySQL 5.5.

# Bugs fixed:

* Performance: InnoDB Storage Engine: Improved concurrency when several ANALYZE TABLE or SHOW TABLE STATUS statements are run simultaneously for InnoDB tables.
* InnoDB Storage Engine: For an InnoDB table created with ROW_FORMAT=COMPRESSED or ROW_FORMAT=DYNAMIC, a query using the READ UNCOMMITTED isolation level could cause the server to stop with an assertion error, if BLOB or other large columns that use off-page storage were being inserted at the same time.
* Partitioning: An INSERT ... ON DUPLICATE KEY UPDATE column = 0 statement on an AUTO_INCREMENT column caused the debug server to crash.
* Several compilation problems were fixed.
* Passing a string that was not null-terminated to UpdateXML() or ExtractValue() caused the server to fail with an assertion.
* Queries executed using the Index Merge access method and a temporary file could return incorrect results.
* The find_files() function used by SHOW statements performed redundant and unnecessary memory allocation.