With a bit of an exception for the era where we were all hard wiring indexes in MySQL using hints... that's what databases should be doing. DB interactions are

With a bit of an exception for the era where we were all hard wiring indexes in MySQL using hints... that's what databases should be doing. DB interactions are supposed to be done using a purely declarative language - postgres has stuck by this the strongest and has been able to make the biggest optimizations in (IMO) a large part due to how little of the internals they've exposed. With pg12 they're making the optimization fences in WITH clauses an accepted give on this point and the discussion on whether to do this or not went back and forth quite a bit.