[Jeremy1026]

bigint gives you 9.2 quintillion options before you run into a collision. Which is obviously not forever proofed, but certainly future proofed.

[smt88]

OP isn't asking for a data type that can hold more than a billion records.

OP needs a way to generate a random ID without checking that the ID has already been used -- s/he wants a UUID. Bigint is FAR too small to do that a billion times without a collision.