Re: UUID v7

Jelte Fennema-Nio <postgres@jeltef.nl>

From: Jelte Fennema-Nio <postgres@jeltef.nl>

To: Aleksander Alekseev <aleksander@timescale.com>

Cc: pgsql-hackers mailing list <pgsql-hackers@postgresql.org>, "Andrey M. Borodin" <x4mmm@yandex-team.ru>, Peter Eisentraut <peter@eisentraut.org>, Sergey Prokhorenko <sergeyprokhorenko@yahoo.com.au>, Przemysław Sztoch <przemyslaw@sztoch.pl>, "David G. Johnston" <david.g.johnston@gmail.com>, Mat Arye <mat@timescaledb.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Nikolay Samokhvalov <samokhvalov@gmail.com>, Junwang Zhao <zhjwpku@gmail.com>

Date: 2024-03-11T15:56:23Z

Lists: pgsql-hackers

Attachments

v21-0001-Implement-UUID-v7.patch (application/octet-stream) patch v21-0001
v21-0003-Run-pgindent.patch (application/octet-stream) patch v21-0003
v21-0005-Change-to-Fixed-Length-Dedicated-Counter-Bits.patch (application/octet-stream) patch v21-0005
v21-0004-Fix-comments-a-bit.patch (application/octet-stream) patch v21-0004
v21-0002-Fix-typos.patch (application/octet-stream) patch v21-0002

Attached a few comment fixes/improvements and a pgindent run (patch 0002-0004)

Now with the added comments, one thing pops out to me: The comments
mention that we use "Monotonic Random", but when I read the spec that
explicitly recommends against using an increment of 1 when using
monotonic random. I feel like if we use an increment of 1, we're
better off going for the "Fixed-Length Dedicated Counter Bits" method
(i.e. change the code to start the counter at 0). See patch 0005 for
an example of that change.

I'm also wondering if we really want to use the extra rand_b bits for
this. The spec says we MAY, but it does remove the amount of
randomness in our UUIDs.

Commits

Fix timestamp overflow in UUIDv7 implementation.
- a5419bc72e22 18.0 landed
Add UUID version 7 generation function.
- 78c5e141e9c1 18.0 landed
Add some UUID support functions
- 794f10f6b920 17.0 landed