Horton

Re: UUID v7

Junwang Zhao <zhjwpku@gmail.com>

View thread View on postgr.es
From: Junwang Zhao <zhjwpku@gmail.com>
To: "Andrey M. Borodin" <x4mmm@yandex-team.ru>
Cc: Sergey Prokhorenko <sergeyprokhorenko@yahoo.com.au>, Jelte Fennema-Nio <postgres@jeltef.nl>, pgsql-hackers mailing list <pgsql-hackers@postgresql.org>, Aleksander Alekseev <aleksander@timescale.com>, Przemysław Sztoch <przemyslaw@sztoch.pl>, Nikolay Samokhvalov <nik@postgres.ai>, "David G. Johnston" <david.g.johnston@gmail.com>, Nick Babadzhanian <pgnickb@gmail.com>, Mat Arye <mat@timescaledb.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Tom Lane <tgl@sss.pgh.pa.us>, Daniel Gustafsson <daniel@yesql.se>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Nikolay Samokhvalov <samokhvalov@gmail.com>, "Kyzer Davis (kydavis)" <kydavis@cisco.com>, Andres Freund <andres@anarazel.de>, "brad@peabody.io" <brad@peabody.io>, Kirk Wolak <wolakk@gmail.com>
Date: 2024-01-30T10:33:21Z
Lists: pgsql-hackers 
Hi Andrey,

On Tue, Jan 30, 2024 at 5:56 PM Andrey M. Borodin <x4mmm@yandex-team.ru> wrote:
>
>
>
> > On 30 Jan 2024, at 12:28, Sergey Prokhorenko <sergeyprokhorenko@yahoo.com.au> wrote:
> >
> >
> > I think this phrase is outdated: "This function can optionally accept a timestamp used instead of current time.
> > This allows implementation of k-way sotable identifiers.”
> Fixed.
>
> > This phrase is wrong: "Both functions return a version 4 (random) UUID.”
> This applies to functions gen_random_uuid() and uuidv4().
> >
> > For this phrase the reason is unclear and the phrase is most likely incorrect:
> > if large batches of UUIDs are generated at the
> > +   same time it's possible that some UUIDs will store a time that is slightly later
> > +   than their actual generation time
>
> I’ve rewritten this phrase, hope it’s more clear now.
>
>
> Best regards, Andrey Borodin.

+Datum
+uuid_extract_var(PG_FUNCTION_ARGS)
+{
+ pg_uuid_t  *uuid = PG_GETARG_UUID_P(0);
+ uint16_t result;
+ result = uuid->data[8] >> 6;
+
+ PG_RETURN_UINT16(result);
+}
\ No newline at end of file

It's always good to add a newline at the end of a  source file, though
this might be nitpicky.

-- 
Regards
Junwang Zhao

Commits

  1. Fix timestamp overflow in UUIDv7 implementation.

  2. Add UUID version 7 generation function.

  3. Add some UUID support functions