[lloyd-christmas]

> but it's not possible to go the other way

Why not? We do exactly that. We prototype in mongo and then migrate to postgres when we're comfortable with where the app is headed.

[wvenable]

I don't mean it's possible to use a different technology; I mean within the same technology (postgres, for example) you can use it both as a normalized relational database and/or as a de-normalized document store.