Life on EC2 can be a bit cramped (or alternately, expensive) in the way of memory. I wanted to slim down my memory footprint for PHP by disabling extra extensions. The biggest culprit in terms of redundancy was MySQL with mysql, mysqli, and pdo_mysql. Using just the mysql extension would be the easy route, but not the future-proofing route. I picked pdo_mysql for a slight edge in flexibility – even if SQL-agnostic applications are a fantasy.
First up for compatibility checking was roundcube. The version available via apt can only use the mysql extension, but that’s a fairly old version and development on the project is still active. Roundcube has moved over to github from SVN which is a nice change. The development version is built entirely around PDO and works quite nicely so far. Upgrading was as simple as copying a few configuration directives from the old version to the new one.
Next was WordPress. The base version still requires mysql and it looks like that will be the case for quite awhile due to compatibility and availability concerns. But some WordPress developers have contributed a set of preliminary patches to allow mysqli and pdo_mysql usage. After a little tinkering, I applied those patches to the latest development release and the blog now runs on PDO too (knock on wood). I made my own fork on github with a PDO branch since tracking the upstream version is going to be a bit more complicated with local changes to maintain.