On Mon, Jan 28, 2013 at 10:52 PM, Katie Filbert <katie.filbert@wikimedia.de> wrote:

PostgreSQL is really not supported at all yet for Wikibase. MediaWiki core support for Postgres is also currently broken, while patches for sites schema updates, ORM support are pending on gerrit.

Look like using PostgreSQL is a no-go for me at the moment for my project.
Both MySQL and PostgreSQL are great but the former is being changed to more proprietary and its open-source's future is uncertain.
I would urge the MediaWiki development community to consider further on this.