Postgres UUIDv7 and per-back end monotonicity

I implemented this in pure Python a few days ago in case anyone finds it helpful, here it is: https://gist.github.com/pirate/7e44387c12f434a77072d50c52a3d...

My implementation supports graceful degradation between nanosecond scale resolution, microsecond, and millisecond, by using 12 bits for each and filling up the leftmost bits of rand_a and rand_b. Not all environments provide high resolution system clocks with no drift, so it's is important to maintain monotonicity when generating IDs with a low-res timestamp as input. You still want the bits that would've held the nanosecond value to be monotonic.

Neither of the existing uuid_utils and uuid7 python libs that can generate UUID7s support this monotonicity property.

Am planning on using this for ArchiveBox append-only "snapshot" records, which are intrinsically linked to time, so it's a good use-case imo.

There's another great resource here that I think is one of the best explainers of UUIDv7: https://antonz.org/uuidv7/

Whatever you do, don't implement the cursed 36-bit whole-second based time UUIDv7 variant that you occasionally see on StackOverflow / blog posts, stick to 48!

This looks great, thanks. But I think gists are better for unimportant stuff - for this I think it deserves its own repo.

It's in the ArchiveBox git repo and I may give it it's own library eventually, but for quick linking it's easier to read / less dependent on the rest of that codebase as a standalone script.