[rozhok]

I did it once in my career. We've had one legacy PHP project designed to work for MySQL. I was in charge of bringing it back to live and I decided to host in on Heroku for the sake of simple deployment. While Heroku does have MySQL addons I opted for using Postgres.

So we've just switched underlying connection and fixed a dozen of (mostly reports) places with plain SQL queries with MySQL-specific syntax. ORM library handled rest just perfectly.