Based on MySQL 5.5.19, including all the bug fixes in it, Percona Server 5.5.19-24.0 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 5.5.19-24.0 milestone at Launchpad.
- Variable innodb_flush_neighbor_pages can be now set to a new value cont. The previously-available option values 0 and 1 now have more descriptive names none and area. The value of none disables the neighbor page flush and area matches the default InnoDB behavior: any dirty pages in the vicinity of the page selected for flushing may be flushed too. The new option value cont improves the neighbor flushing by considering only contiguous blocks of neighbor pages, thus performing the flush by sequential instead of random I/O. (Yasufumi Kinoshita, Laurynas Biveinis)
- Improvements to the XtraDB’s sync flush algorithm. If the XtraDB checkpoint age grows dangerously close to its limit and XtraDB is forced to perform a sync flush, these changes should slightly improve the user query performance instead of completely blocking them. (Yasufumi Kinoshita, Laurynas Biveinis)