Replace MySQL with MariaDB on Ubuntu 12.04 LTS
MariaDB includes important security fixes, a high performance drop-in replacement for the InnoDB storage engine, named XtraDB, and is a completely compatible replacement for MySQL without the doubts surrounding Oracle's stewardship of the MySQL project. In addition, MariaDB is headed up by the original MySQL project founder and lead, Michael "Monty" Widenius. In short, there is no good reason not to use this exciting fork of the venerable MySQL database project.
Add the MariaDB repository
We need to add a new repository to our list of recognized package locations and ensure the digital signature is recognized.
Upgrade the packages
This one is very straightforward:
aptitude upgrade mysql-common libmysqlclient18
Aptitude will respond with a bunch of messages and ask you for confirmation before it attempts to overwrite what you have in place. If all goes well you will now have MariaDB installed.