UUIDv4 is random. UUIDv3 and v5 are just namespace+name hashes (where namespace is often Nil UUID adding to the problem). Those 3 hashes are, in general, not go

UUIDv4 is random. UUIDv3 and v5 are just namespace+name hashes (where namespace is often Nil UUID adding to the problem). Those 3 hashes are, in general, not good candidates for pk on large resources because they mess up the index which likes monotonic increments on new values. The bottom line is UUIDs are not bad, you just need to be aware of couple of things when working with them.