Horton

Re: What is a typical precision of gettimeofday()?

Andrey Borodin <x4mmm@yandex-team.ru>

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From: "Andrey M. Borodin" <x4mmm@yandex-team.ru>
To: Aleksander Alekseev <aleksander@timescale.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>, Tom Lane <tgl@sss.pgh.pa.us>, Hannu Krosing <hannuk@google.com>, Peter Eisentraut <peter@eisentraut.org>
Date: 2024-07-03T10:38:14Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Force LC_NUMERIC to C while running TAP tests.

  2. Minor tweaks for pg_test_timing.

  3. Change pg_test_timing to measure in nanoseconds not microseconds.


> On 3 Jul 2024, at 13:48, Aleksander Alekseev <aleksander@timescale.com> wrote:
> 
> Hi,
> 
>> That’s a very interesting result, from the UUID POV!
>> If time is almost always advancing, using time readings instead of a counter is very reasonable: we have interprocess monotonicity almost for free.
>> Though time is advancing in a very small steps… RFC assumes that we use microseconds, I’m not sure it’s ok to use 10 more bits for nanoseconds…
> 
> A counter is mandatory since someone can for instance change the
> system's time while the process is generating UUIDs. You can't
> generally assume that local time of the system is monotonic.

AFAIR according to RFC when time jumps backwards, we just use time microseconds as a counter. Until time starts to advance again.


Best regards, Andrey Borodin.