Based on MySQL 5.5.30, including all the bug fixes in it, Percona Server 5.5.30-30.2 is now the current stable release in the 5.5 series. All of Percona‘s software is open-source and free, all the details of the release can be found in the 5.5.30-30.2 milestone at Launchpad.
Percona Server has implemented priority connection scheduling for the Thread Pool. (Alexey Kopytov)
Percona Server .tar.gz binaries will now be shipped with the libjemalloc library. jemalloc package is now available in our apt/yum repositories as well. In case newer version is available in the distribution repositories that version will be used. Benchmark showing the impact of memory allocators on MySQL performance can be found in this blogpost. (Ignacio Nin)
This release of Percona Server has fixed a number of performance bugs. (Alexey Kopytov)
Drop table performance has been removed and its controlling variable innodb_lazy_drop_table has been deprecated. Feature has been removed because the upstream DROP TABLE implementation has been improved. (Laurynas Biveinis)
Due to parse error in the percona-server.spec Percona Server rpm packages couldn’t be built on RHEL 5 and CentOS 5. Bug fixed #1144777 (Ignacio Nin).
When mysqldump was used with --innodb-optimize-keys option it produced invalid SQL for cases when there was an explicitly named foreign key constraint which implied an implicit secondary index with the same name. Fixed by detecting such cases and omitting the corresponding secondary keys from deferred key creation optimization. Bug fixed #1081016 (Alexey Kopytov).
Percona Server was built with YaSSL which could cause some of the programs that use it to crash. Fixed by building packages with OpenSSL support rather than the bundled YaSSL library. Bug fixed #1104977 (Ignacio Nin).
The log tracker thread was unaware of the situation when the oldest untracked log records are overwritten by the new log data. In some corner cases this could lead to assertion errors in the log parser or bad changed page data. Bug fixed #1108613 (Laurynas Biveinis).
Ported a fix from MariaDB for the upstream bug #63144. CREATE TABLE or CREATE TABLE IF NOT EXISTS statements on an existing table could wait on a metadata lock instead of failing or returning immediately if there is a transaction that executed a query which opened that table. Bug fixed #1127008 (Sergei Glushchenko).
Fixed upstream bug #49169 by avoiding the malloc call in the read_view_create_low() in most cases. This significantly improves InnoDB scalability on read-only workloads, especially when the default glibc memory allocator is used. Bug fixed #1131187 (Alexey Kopytov).
Removed trx_list scan in read_view_open_now() which is another problem originally reported as upstream bug #49169. This also provides much better scalability in InnoDB high-concurrent workloads. Bugs fixed #1131189 (Alexey Kopytov).
In the event that a slave was disconnected from the master, under certain conditions, upon reconnect, it would report that it received a packet larger than the slave_max_allowed_packet variable. Bug fixed #1135097 (George Ormond Lorch III).
Percona Server would re-create the test database when using rpm on server upgrade, even if the database was previously removed. Bug fixed #710799 (Alexey Bychko).
Debian packages included the old version of innotop. Fixed by removing innotop and its InnoDBParser Perl package from source and Debian installation. Bug fixed #1032139 (Alexey Bychko).
UDF/configure.ac was incompatible with automake 1.12. Bug fixed #1099387 (Alexey Bychko).
Reduced the overhead from innodb_pass_corrupt_table` value checks by optimizing them for better CPU branch prediction. Bug fixed #1125248 (Alexey Kopytov).
dialog.so used by the PAM Authentication Plugin couldn’t be loaded with Perl and Python clients when plugin-dir option was set in the [client] section of the my.cnf. Bug fixed #1155859 (Sergei Glushchenko).
Ported back from the upstream MySQL 5.6 the fix for unnecessary log_flush_order_mutex acquisition. Bug fixed #1163262 (Alexey Kopytov).
When mysqldump was used with --innodb-optimize-keys and --no-data options, all secondary key definitions would be lost. Bug fixed #989253 (Alexey Kopytov).
Warning about the Percona Toolkit UDFs was omitted when installing from Percona’s Debian repositories. Bug fixed #1015506 (Alexey Bychko).
Percona Server was missing help texts in the MySQL client because the help tables were missing. Bug fixed #1041981 (Alexey Bychko).
Fixed the upstream bug #68197 that caused InnoDB to misclassify internal read operations as synchronous when they were actually asynchronous when Thread Pool feature was used. Bug fixed #1107539 (Sergei Glushchenko).
Other bug fixes: bug fixed #1103850 (Laurynas Biveinis), bug fixed #1146621 (Laurynas Biveinis), bug fixed #1050536 (Alexey Bychko), bug fixed #1144059 (Roel Van de Paar), bug fixed #1154962 (Hrvoje Matijakovic), bug fixed #1154959 (Hrvoje Matijakovic), bug fixed #1154957 (Hrvoje Matijakovic), bug fixed #1154954 (Hrvoje Matijakovic).