> This isn't remotely true; it turns what looks like an in-memory access into a network round trip. Navigating your database using an idiom of lists and member accesses is a fast path to n+1 queries all over the place, or ORM tuned to eagerly fetch the whole world when you only touch a tiny piece of it.
That isn't true for e.g. Django's ORM, which lazily evaluates the query and only actually accesses the db after that, with a single query, and filtering done in SQL.