Whatever your overall requirements are, if you've already decided on a relational DB to solve them, you probably want bigserial PKs in said DB. The DBMS is opti

Whatever your overall requirements are, if you've already decided on a relational DB to solve them, you probably want bigserial PKs in said DB. The DBMS is optimized for that (as I've noticed in Postgres), and you don't gain anything by using UUIDs instead there. UUID in a secondary col or elsewhere in your system, that's fine. If you have to look up by UUID from outside and have no foreign keys, UUID PKs can be faster. But that's the classic use case for a non-relational DB.