New Features
Percona XtraDB Cluster has implemented Support for PROXY protocol. The implementation is based on a patch developed by Thierry Fournier.
Variable wsrep_dirty_reads now has Global scope as well. (PXC-373).
MTR coverage has been added to all tests in galera suite. Many bugs associated with mtr tests have been fixed.
A new variable gcache.keep_pages_count, analogous to gcache.keep_pages_size, has been added. The variable limits the number of overflow pages rather than the total memory occupied by all overflow pages. Whenever either of the variables are updated at runtime to a non-zero value, cleanup is called on excess overflow pages to delete them. This feature also fixes the bugs with integer overflow in the gcache module.
Updates have been made to wsrep code to ensure greater concordance with binary log and GTID so that failover of async slaves, among nodes of the cluster is seamless and consistent. To ensure this in #1421360, all FLUSH commands (except FLUSH BINARY LOG and FLUSH LOGS, and read lock-based flush such as FLUSH TABLES WITH READ LOCK and FLUSH TABLES FOR EXPORT), ANALYZE TABLE, Percona Server-specific flush statements for user statistics and page tracking bitmaps are executed under Total Order Isolation (TOI) so that they are replicated to other nodes in the cluster when they are written to binary log.
Percona XtraDB Cluster has temporarily disabled savepoints in triggers and stored functions. The reason is that even having fixed bug #1438990 and bug #1464468 we have found more cases where savepoints in triggers break binary logging and replication, resulting in server crashes and broken slaves. This feature will be disabled until the above issues are properly resolved.
Bugs fixed
SHOW STATUS LIKE ... and SHOW STATUS were taking time proportional to size of gcache.size. Bug fixed #1462674.
When disk space would get filled with gcache.page files, Galera would crash when the next page file was created. Bug fixed #1488535.
XtraBackup SST didn’t clobber backup-my.cnf which caused SST to fail. Bug fixed #1431101.
Error from process::wait was not checked in joiner thread leading to joiner starting erroneously even when SST had failed. Bug fixed #1402166.
Due to an regression introduced in Percona XtraDB Cluster 5.6.24-25.11, update of the wsrep_cluster_address variable, following the update of wsrep_provider_options variable would cause the server to deadlock. Bug fixed PXC-421.
mysqldump SST could stall due to a regression in desync mutex introduced in Percona XtraDB Cluster 5.6.24-25.11 by fixing the bug #1288528. Bug fixed PXC-423.
mysql_tzinfo_to_sql sets wsrep_replicate_myisam variable at session scope so that statements are replicated correctly. Bug fixed PXC-332.
Percona-XtraDB-Cluster-devel-56 package was not included in the Percona-XtraDB-Cluster-full-56 metapackage on CentOS due to a conflict with upstream mysql package. Bug fixed PXC-381.
Running service mysql start and then service mysql@boostrap start afterwards would cause server shutdown. Bug fixed PXC-385.
NO_WRITE_TO_BINLOG / LOCAL for ANALYZE TABLE, OPTIMIZE TABLE, REPAIR TABLE, FLUSH commands will ensure it is not written to binary log (as in mysql async replication) and not replicated in wsrep. Bug fixed PXC-391.
FLUSH TABLES WITH READ LOCK failure (with non-existent tables) didn’t resume the galera provider, causing deadlock. Bug fixed PXC-399.
Percona XtraDB Cluster will not blocking DDL statements on tables which are used with ... FOR EXPORT or ... WITH READ LOCK, it will give return an error message about read lock. Bug fixed PXC-403.
Fixed the update of variable wsrep_slave_threads variable regarding the default value assignment, invalid value truncation, and error issued while threads are still being closed. Bug fixed PXC-420.
Server would crash during startup if gcs.fc_limit variable was specified twice in wsrep_provider_options. Bug fixed PXC-428.
The mysql client in Percona XtraDB Cluster has been built with system readline instead of editline. Bug fixed PXC-430.
Bugs in 32-bit galera associated with statvfs in available_storage and integer overflow after multiplication in offset calculation have been fixed. Bug fixed PXC-433.
Galera 3 was failing to build on all non-intel platforms. Architecture specific CCFLAGS have been removed and provision for inheriting CCFLAGS, CFLAGS, CXXFLAGS and LDFLAGS have been added to SConstruct. Bug fixed PXC-326.
Non-global read locks such as FLUSH TABLES WITH READ LOCK and FLUSH TABLES FOR EXPORT paused galera provider but didn’t block commit globally which wsrep_to_isolation_begin (for DDL) was made aware of. Bug fixed PXC-403.
Following bug fixes have been ported from Percona Server 5.6.26-74.0: bug #1454441, bug #1470677, bug #1472256, bug #1472251, and bug #1464468.
Other bugs fixed: PXC-370, PXC-429, PXC-415, PXC-400 and PXC-416.
