Good intro article. I'd always heard that serial ints aren't guaranteed to be ordered but never knew why (because they are generated non-transactionally..so if

Good intro article. I'd always heard that serial ints aren't guaranteed to be ordered but never knew why (because they are generated non-transactionally..so if an INSERT transaction rolls back the id that would have been used is effectively consumed/skipped). What I see a lot in practice is a bigint numeric id for internal use (better for joins, FKs) and also a textual token for public use, perhaps with a typed prefix indicate the type of record it's identifying (U-AS234FDS for User, etc)