I agree with patio11. Just build the app with whatever technology stack you are comfortable with (or want to do with). Keep the scalability problems for later.

I agree with patio11. Just build the app with whatever technology stack you are comfortable with (or want to do with). Keep the scalability problems for later. Get your customers first. I usually (done it just twice) launch with sqlite. Makes it easier to move around the db or even the site. But beware of sqlite. Caution: Migrating from sqlite to postgresql might be a bit of a 'solvable' problem.