Generate Timebased UUID in elixir

Which relational-mapping library are you using, if any?

I am using Xandra for cassandra in Elixir if you mean that.

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 .

Thank you for the details much appreciated.

I do tried V1 UUID but the rows where not inserted as they come it was randomized.

I can think of two possible reasons:

1. Maybe Cassandra is overwriting the values by values it generates itself?
2. Maybe you’re trying to insert string-encoded UUIDs whereas Xandra uses a raw binary encoding format as default?

Actually if the type is timebased uuid then I can insert now() which it converts to uuid internally.

ksuid is sortable uuid

KSUID is great, and monotonically increasing. Couldn’t push for it more.

For lexicographically sortable UUIDs I prefer UUIDv6.

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.