[zadikian]

Common one is if you want two structs deemed "equivalent" based on a few fields to get the same ID, and you're only concerned about accidental collision. There are valid use cases for that, but I've also seen it misused often.

v7 rough ordering also helps as a PK in certain sharded DBs, while others want random, or nonsharded ones usually just serial int.

[8organicbits]

Have you seen UUIDv3/v5 used there though? I've seen lots of md5 historically and sha variants recently, but not the UUID approach.

[zadikian]

Yeah, I've seen both 3 and 5 used, not just hashes in some custom format. That way it works with Postgres uuid type etc.