ksuid is sortable uuid

I’ll throw ecto_ulid out there too. ULID is a pretty nice ID type (and while I realize this post is about IDs in Cassandra) but its lack of support in Postgres turned into a PITA. I was storing it as a :binary_id since it’s a 128bit integer but querying by the human-readable format was impossible; I had to convert it manually and that got old.

Anyway, here’s a good write-up of the differences between ULID & KSUID. Both are likely great options for your use case.

A cursory look through Xandra’s documentation and source code shows that Xandra does not (yet?) expose any way to generate timeuuid’s in Elixir (but only encoding/decoding values genereated from within Cassandra).

I did find another library called ‘Cassandra’ which has not seen very much usage and has not been updated in a couple of years, but it does contain an internal (undocumented) module called Cassandra.UUID which seems to generate UUIDs in the desired format.

Looking at that module in a bit more detail, it seems like the actual work is offloaded to elixir_uuid (which is stable and widely used), and that Cassandra’s timeuuids are nothing else than ‘v1’ UUIDs.

So using elixir_uuid is probably the best approach .