| From: | Aleksander Alekseev <aleksander(at)timescale(dot)com> |
|---|---|
| To: | pgsql-hackers mailing list <pgsql-hackers(at)postgresql(dot)org> |
| Cc: | Andrey Borodin <x4mmm(at)yandex-team(dot)ru>, Przemysław Sztoch <przemyslaw(at)sztoch(dot)pl>, Sergey Prokhorenko <sergeyprokhorenko(at)yahoo(dot)com(dot)au>, Jelte Fennema-Nio <postgres(at)jeltef(dot)nl>, Nick Babadzhanian <pgnickb(at)gmail(dot)com>, Mat Arye <mat(at)timescaledb(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Daniel Gustafsson <daniel(at)yesql(dot)se>, Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, Nikolay Samokhvalov <samokhvalov(at)gmail(dot)com>, "Kyzer Davis (kydavis)" <kydavis(at)cisco(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, "brad(at)peabody(dot)io" <brad(at)peabody(dot)io>, Kirk Wolak <wolakk(at)gmail(dot)com> |
| Subject: | Re: UUID v7 |
| Date: | 2024-01-18 16:21:52 |
| Message-ID: | CAJ7c6TPh5wbPDEoDa2-9w5N=eEsK4tqA4dGidnays6e=8T20Qg@mail.gmail.com |
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| Lists: | pgsql-hackers |
Hi Andrey,
> > Timestamp and TimestampTz are absolutely the same thing.
> My question is not about Postgres data types. I'm asking about examples in the standard.
>
> There's an example 017F22E2-79B0-7CC3-98C4-DC0C0C07398F. It is expected to be generated on "Tuesday, February 22, 2022 2:22:22.00 PM GMT-05:00".
> It's exaplained to be 164555774200000ns after 1582-10-15 00:00:00 UTC.
>
> But 164555774200000ns after 1582-10-15 00:00:00 UTC was 2022-02-22 19:22:22 UTC. And that was 2022-02-23 00:22:22 in UTC-05.
Not 100% sure which text you are referring to exactly, but I'm
guessing it's section B.2 of [1]
"""
This example UUIDv7 test vector utilizes a well-known 32 bit Unix
epoch with additional millisecond precision to fill the first 48 bits
[...]
The timestamp is Tuesday, February 22, 2022 2:22:22.00 PM GMT-05:00
represented as 0x17F22E279B0 or 1645557742000
"""
If this is the case, I think the example is indeed wrong:
```
=# select extract(epoch from 'Tuesday, February 22, 2022 2:22:22.00 PM
GMT-05:00' :: timestamptz)*1000;
?column?
----------------------
1645521742000.000000
(1 row)
```
And the difference between the value in the text and the actual value
is 10 hours as you pointed out.
Also you named the date 1582-10-15 00:00:00 UTC. Maybe you actually
meant 1970-01-01 00:00:00 UTC?
[1]: https://www.ietf.org/archive/id/draft-peabody-dispatch-new-uuid-format-04.html
--
Best regards,
Aleksander Alekseev
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