Recently, I was somewhat bored and decided to switch from a MySQL 5.1 backend to MySQL 5.5 for my site (of which you have the distinct pleasure of reading).  While doing a little Googling,  I remembered MariaDB. MariaDB is marketed as “An enhanced, drop-in replacement … “How-to: Switching WordPress from MySQL 5.1 to MariaDB 5.5 on CentOS/RHEL 6”