Horton

Re: UUID v7

x4mmm@yandex-team.ru

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From: "Andrey M. Borodin" <x4mmm@yandex-team.ru>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Sergey Prokhorenko <sergeyprokhorenko@yahoo.com.au>, Jelte Fennema-Nio <postgres@jeltef.nl>, Michael Paquier <michael@paquier.xyz>, Aleksander Alekseev <aleksander@timescale.com>, pgsql-hackers mailing list <pgsql-hackers@postgresql.org>, Peter Eisentraut <peter@eisentraut.org>, 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>, Stepan Neretin <sncfmgg@gmail.com>
Date: 2024-11-06T18:14:29Z
Lists: pgsql-hackers 

> On 5 Nov 2024, at 23:56, Andrey M. Borodin <x4mmm@yandex-team.ru> wrote:
> 
> <v30-0001-Implement-UUID-v7.patch>

Some more thoughts on this patch version:

0. Comment mentioning nanoseconds, while we do not need to carry anything
/* Convert TimestampTz back and carry nanoseconds. */

1. There's unnecessary &3 in
uuid->data[7] = uuid->data[7] | ((uuid->data[8] >> 6) & 3);

2. Currently we store 0..999 microseconds in 10 bits, so values 1000..1023 are unused. We could use them for overflow. That would slightly increase non-overflowing capacity when generating more than million UUIDs per second on one backend. However, given current performance of our CSPRNG I do not think this feature worth code complexity.


Best regards, Andrey Borodin.

Commits

  1. Fix timestamp overflow in UUIDv7 implementation.

  2. Add UUID version 7 generation function.

  3. Add some UUID support functions