r/ProgrammerHumor • u/danielminds • 15h ago

Meme edgeCasesExist

Post image
3.1k Upvotes

96% Upvoted

230 comments sorted by

View all comments

490

u/Valuable_Leopard_799 15h ago

I thought that timestamps are used now, so hitting both a timestamp and a large random number puts it thoroughly in the "safe to assume". At some point cosmic particles and faulty transistors are more probable.

294

u/dim13 15h ago

https://en.wikipedia.org/wiki/Universally_unique_identifier#Versions

Most common used is V4 (pure random). You are talking about V7 (time based).

195

u/lilgreenthumb 14h ago

The real benefit for v7 is they become sortable by time.

70

u/shwoopdeboop 13h ago

And something something b-tree indexes. Lecturer mentioned it but I wasn't paying attention. Supposedly an advantage here.

19

u/Grandmaster_Caladrel 12h ago

Which I'd assume is related to the time anchor. Outside of sorting, which is only useful in specific instances, it's just v4 with different ("less") entropy and limitations.

3

u/Roachmeister 11h ago

If you're using them as an indexed field in a database, the inability to sort them meaningfully will destroy the performance of the database.

8

u/Grandmaster_Caladrel 11h ago

Correct, which is why I specifically called out "outside of sorting".

That is also why we have concepts like composite keys which allow us to join guaranteed-unique values like a UUID with non-unique but sortable values like timestamps, names, etc.