Replication: Previously, replication slaves could connect to the master server through master accounts that use nonnative authentication, except Windows native authentication. This is now also true for Windows native authentication.

Performance of metadata locking operations on Windows XP systems was improved by instituting a cache for metadata lock objects. This permits the server to avoid expensive operations for creation and destruction of synchronization objects on XP. A new system variable, metadata_locks_cache_size, permits control over the size of the cache. The default size is 1024. (Bug #12695572)

InnoDB Storage Engine: An internal deadlock could occur within InnoDB, on a server doing a substantial amount of change buffering for DML operations, particularly DELETE statements. (Bug #13340047)

Replication: When a statement containing a large number of rows to be applied on a slave table that does not contain a primary key, a considerable amount of time can be needed to find and change all the rows that are to be changed. The current fix helps diagnose this issue by printing a message to the error log if the execution time for a given statement replicated using row-based replication takes more than 60 seconds. log_warnings must be greater than 1 for this message to be printed to the error log. (Bug #11760927, Bug #53375)

Rounding DBL_MAX returned DBL_MAX, not 'inf'. (Bug #13261955)

mysql_upgrade did not upgrade the system tables or create the mysql_upgrade_info file when run with the --write-binlog or --skip-write-binlog option. (Bug #60223, Bug #11827359)

If a plugin was uninstalled, thread local variables for plugin variables of string type with wth PLUGIN_VAR_MEMALLOC flag were not freed. (Bug #56652, Bug #11763882)

Deadlock could occur when these four things happened at the same time: 1) An old dump thread was waiting for the binary log to grow. 2) The slave server that replicates from the old dump thread tried to reconnect. During reconnection, the new dump thread tried to kill the old dump thread. 3) A KILL statement tried to kill the old dump thread. 4) An INSERT statement caused a binary log rotation. (Bug #56299, Bug #11763573)