An int PK does not give you 4 billion rows. For example, in Postgres every time an insert transaction has to rollback, the id's that would have been used by tha

An int PK does not give you 4 billion rows. For example, in Postgres every time an insert transaction has to rollback, the id's that would have been used by that insert are discarded and gone forever. Likewise people often don't realize that Postgres' very convenient upsert syntax (insert on conflict do update) will consume id's from the sequence _every time it runs_. If you do an upsert with 100 rows, it will peel off 100 new id's just in case they're needed... if they aren't used, they're discarded. This can chew through 4 billion id's really, really fast. Personally I would only use an int PK in a table where you know the bounds of the data with very high confidence. Like, at my last job the software involved working with our client's physical store locations. If we managed to capture the entire North American market for the type of business that we worked with, we'd be looking at about 50k stores.