Horton

Re: UUID v7

x4mmm@yandex-team.ru

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From: Andrey Borodin <x4mmm@yandex-team.ru>
To: Jelte Fennema-Nio <postgres@jeltef.nl>
Cc: Przemysław Sztoch <przemyslaw@sztoch.pl>, Sergey Prokhorenko <sergeyprokhorenko@yahoo.com.au>, Aleksander Alekseev <aleksander@timescale.com>, pgsql-hackers mailing list <pgsql-hackers@postgresql.org>, 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: 2024-01-18T13:17:54Z
Lists: pgsql-hackers

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> On 17 Jan 2024, at 02:19, Jelte Fennema-Nio <postgres@jeltef.nl> wrote:

I want to ask Kyzer or Brad, I hope they will see this message. I'm working on the patch for time extraction for v1, v6 and v7.

Do I understand correctly, that UUIDs contain local time, not UTC time? For examples in [0] I see that "A.6. Example of a UUIDv7 Value" I see that February 22, 2022 2:22:22.00 PM GMT-05:00 results in unix_ts_ms = 0x017F22E279B0, which is not UTC, but local time.
Is it intentional? Section "5.1. UUID Version 1" states otherwise.

If so, I should swap signatures of functions from TimestampTz to Timestamp.
I'm hard-coding examples from this standard to tests, so I want to be precise...

If I follow the standard I see this in tests:
+-- extract UUID v1, v6 and v7 timestamp
+SELECT uuid_extract_time('C232AB00-9414-11EC-B3C8-9F6BDECED846') at time zone 'GMT-05';
+         timezone         
+--------------------------
+ Wed Feb 23 00:22:22 2022
+(1 row)

Current patch version attached. I've addressed all other requests: function renames, aliases, multiple functions instead of optional params, cleaner catalog definitions, not throwing error when [var,ver,time] value is unknown.
What is left: deal with timezones, improve documentation.


Best regards, Andrey Borodin.

[0] https://datatracker.ietf.org/doc/html/draft-ietf-uuidrev-rfc4122bis#name-example-of-a-uuidv1-value

Commits

  1. Fix timestamp overflow in UUIDv7 implementation.

  2. Add UUID version 7 generation function.

  3. Add some UUID support functions