Not sure what database you are using, but at least PostgreSQL has a real UUID type that is not stored as a string into the database. Of course that’s 128 bits instead of 64.

If you intend to store 64 bit unsigned integers into the DB, note that PostgreSQL’s bigint type is signed, and so cannot fit all unsigned values.

If you are not using PostgreSQL, just ignore this post.

Thanks I’m actually moving from Postgres to Clickhouse, here’s the repo: GitHub - plausible/analytics: Open source, privacy-first web analytics. Lightweight, cookie-free Google Analytics alternative. Self-hosted or cloud. · GitHub

I was using the UUID type in Postgres but after a consultation with some Clickhouse experts they told me that UInt64 is smaller and has enough cardinality for my use-case.

The problem is that it can deplete the entropy source and is slower than most PRNGs. So the question is what is needed. @ukutaht maybe you could use UUIDv6, which is not random at all. Especially for utility that is about analytics, which will need to store time anyway.