Horton

Re: UUID v7

x4mmm@yandex-team.ru

View thread View on postgr.es
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>
Date: 2024-11-01T04:53:36Z
Lists: pgsql-hackers 

> On 1 Nov 2024, at 03:00, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> 
> Therefore, if the
> system clock moves backward due to NTP, we cannot guarantee
> monotonicity and sortability. Is that right?

Not exactly. Monotonicity is ensured for a given backend. We make sure that timestamp is advanced at least for ~250ns forward on each UUID generation. 60 bits of time are unique and ascending for a given backend.

Thanks!


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