Changed the default value of innodb_flush_log_at_trx_commit from 0 to 1. If you have not specified it explicitly in your my.cnf, and your application runs much slower with this new release, it is because the value 1 causes a log flush to disk at each transaction commit.

Fixed a bug: InnoDB forgot to call pthread_mutex_destroy() when a table was dropped. That could cause memory leakage on FreeBSD and other non-Linux Unixes.

Fixed a bug: MySQL could erroneously return 'Empty set' if InnoDB estimated an index range size to 0 records though the range was not empty; MySQL also failed to do the next-key locking in the case of an empty index range.

Fixed a bug: GROUP BY and DISTINCT could treat NULL values inequal.