Shared-hosting providers generally offer MySQL as part of their low-end packages, but not PostgreSQL (I assume this is because MySQL is easier to administer in

Shared-hosting providers generally offer MySQL as part of their low-end packages, but not PostgreSQL (I assume this is because MySQL is easier to administer in a shared environment). So if you want your web app to use PostgreSQL, you have to find a PostgreSQL-specific provider or take responsibility for administering your own box.