| From: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> |
|---|---|
| To: | Andrey Borodin <x4mmm(at)yandex-team(dot)ru> |
| Cc: | Daniel Verite <daniel(at)manitou-mail(dot)org>, Peter Eisentraut <peter(at)eisentraut(dot)org>, Jelte Fennema-Nio <postgres(at)jeltef(dot)nl>, Sergey Prokhorenko <sergeyprokhorenko(at)yahoo(dot)com(dot)au>, Przemysław Sztoch <przemyslaw(at)sztoch(dot)pl>, Michael Paquier <michael(at)paquier(dot)xyz>, Aleksander Alekseev <aleksander(at)timescale(dot)com>, Pgsql-Hackers Mailing List <pgsql-hackers(at)postgresql(dot)org>, "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>, Mat Arye <mat(at)timescaledb(dot)com>, Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, Nikolay Samokhvalov <samokhvalov(at)gmail(dot)com>, Junwang Zhao <zhjwpku(at)gmail(dot)com>, Stepan Neretin <sncfmgg(at)gmail(dot)com> |
| Subject: | Re: UUID v7 |
| Date: | 2025-03-26 17:06:10 |
| Message-ID: | CAD21AoCr1aZdEBzDtU5Lg1XssA68L0uRyWC-a4DjmaXGLK++zA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Mar 26, 2025 at 6:00 AM Andrey Borodin <x4mmm(at)yandex-team(dot)ru> wrote:
>
>
>
> > On 26 Mar 2025, at 08:32, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> >
> > Please review it.
>
> The patch looks good to me except one nit.
> +WITH uuidts AS (
> + SELECT y, ts as ts, lag(ts) OVER (ORDER BY y) AS prev_ts
> + FROM (SELECT y, uuid_extract_timestamp(uuidv7((y || ' years')::interval)) AS ts FROM generate_series(-50, 10889 - extract(year from now())::int) y)
> +)
> +SELECT y, ts, prev_ts FROM uuidts WHERE ts < prev_ts;
>
> if "extract(year from now())::int)" runs slightly before new year and the rest of the test after - the test will fail. How about avoiding overflow by using 10888 instead of 10889?
Agreed. I've done this in the attached patch.
> If we are sure citizen time never will go back, IMO we can safely move other border back to -55.
Yes. Or I think we can verify the range from 1970 to 10888 like I did
in the updated patch.
> Also the test is not proof to NTP time drift during New Year's edge, but it's hardly a problem. The test, NTP clock sync and New Year millisecond must coincide for a false failure.
Agreed.
Regards,
--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com
| Attachment | Content-Type | Size |
|---|---|---|
| v6-0001-Fix-timestamp-overflow-in-UUIDv7-implementation.patch | application/octet-stream | 7.1 KB |
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