NEW FEATURES
Percona XtraDB Cluster now allows reads in non-primary state by introducing a new session variable, wsrep_dirty_reads. This variable is boolean and is OFF by default. When set to ON, a Percona XtraDB Cluster node accepts queries that only read, but not modify data even if the node is in the non-PRIM state (#1407770).
Percona XtraDB Cluster now allows queries against INFORMATION_SCHEMA and PERFORMANCE_SCHEMA even with variables wsrep_ready and wsrep_dirty_reads set to OFF. This allows monitoring applications to monitor the node when it is even in non-PRIM state (#1409618).
wsrep_replicate_myisam variable is now both session and global variable (#1280280).
Percona XtraDB Cluster now uses getifaddrs for node address detection. It detects the address from the interface to which mysqld is bound if the address is not obtained from bind_address or wsrep_node_address, when both are unset (#1252700).
Percona XtraDB Cluster has implemented two new status variables: wsrep_cert_bucket_count and wsrep_gcache_pool_size for better instrumentation of galera memory usage. wsrep_cert_bucket_count shows the number of cells in the certification index hash-table and wsrep_gcache_pool_size shows the size of the page pool and/or dynamic memory allocated for gcache (in bytes).
BUGS FIXED
Using concurrent REPLACE, LOAD DATA REPLACE or INSERT ON DUPLICATE KEY UPDATE statements in the READ COMMITTED isolation level or with the innodb_locks_unsafe_for_binlog option enabled could lead to a unique-key constraint violation. Bug fixed #1308016.
Using the Rolling Schema Upgrade as a schema upgrade method due to conflict with wsrep_desync would allows only one ALTER TABLE to run concurrently. Bugs fixed #1330944 and #1330941.
SST would resume even when the donor was already detected as being in SYNCED state. This was caused when wsrep_desync was manually set to OFF which caused the conflict and resumed the donor sooner. Bug fixed #1288528.
DDL would fail on a node when running a TOI DDL, if one of the nodes has the table locked. Bug fixed #1376747.
xinet.d mysqlchk file was missing type = UNLISTED to work out of the box. Bug fixed #1418614.
Conflict between enforce_storage_engine and wsrep_replicate_myisam for CREATE TABLE has been fixed. Bug fixed #1435482.
A specific trigger execution on the master server could cause a slave assertion error under row-based replication. The trigger would satisfy the following conditions: 1) it sets a savepoint; 2) it declares a condition handler which releases this savepoint; 3) the trigger execution passes through the condition handler. Bug fixed #1438990.
Percona XtraDB Cluster Debian init script was testing connection with wrong credentials. Bug fixed #1439673.
Race condition between IST and SST fixed in xtrabackup-v2 SST. Bugs fixed #1441762, #1443881, and #1451524.
SST will now fail when move-back fails instead of continuing and failing at the next step. Bug fixed #1451670.
Percona XtraDB Cluster .deb binaries were built without fast mutexes. Bug fixed #1457118.
The error message text returned to the client in the non-primary mode is now more descriptive ("WSREP has not yet prepared node for application use"), instead of "Unknown command" returned previously. Bug fixed #1426378.
Out-of-bount memory access issue in seqno_reset() function has been fixed.
wsrep_local_cached_downto would underflow when the node on which it is queried has no writesets in gcache.
Other bugs fixed: #1290526.
