You have a sever with MySQL already. We had Rackspace servers in the place I worked a couple of years ago and they didn't offer Postgress as far as I remember.

You have a sever with MySQL already. We had Rackspace servers in the place I worked a couple of years ago and they didn't offer Postgress as far as I remember. (You could install and manage it on a virtual machine but then you had to do everything yourself, while they had managed MySQL servers available). Also setting up master / slave replication seems easier with MySQL as I understand - I never tried with Postgress but did with MySQL.