As far as I understand mySQL

- You have to choose engines

- Some features (e.g. ACID Transactions) don't work in some engines.

I'm not sure exactly why this is a feature. In PostgreSQL (and in most sane DB software)

- You don't have to choose engines

- All features work all the time. There's no posiblity of foolery like, say, beginning a transaction and then updating two tables, then finding that one of the tables will ignore the transaction but the other won't.