:self::MySQL 5.5.22: is available in the :self:113:: PPA. It's available in Natty, Oneiric and Precise. It's a :ext:http://dev.mysql.com/doc/refman/5.5/en/news-5-5-22.html:bug fix release: that addresses a possible loss of data on update, a bug where master and slave could go out of sync...
Note that mysql-5.5 was also uploaded to the official repository of Precise 12.04. Official repos of Oneiric and previous releases are still on Mysql 5.1.
