From: | Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com> |
---|---|
To: | bruce(at)momjian(dot)us |
Cc: | jobin(dot)augustine(at)percona(dot)com, hamid(dot)akhtar(at)percona(dot)com, jobinau(at)gmail(dot)com, pgsql-bugs(at)lists(dot)postgresql(dot)org, andres(at)anarazel(dot)de |
Subject: | Re: BUG #18046: stats collection behaviour change is affecting the usability of information. |
Date: | 2023-09-07 05:12:32 |
Message-ID: | 20230907.141232.226530973179233921.horikyota.ntt@gmail.com |
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Lists: | pgsql-bugs |
At Wed, 6 Sep 2023 12:57:01 -0400, Bruce Momjian <bruce(at)momjian(dot)us> wrote in
> > Expected behaviour(works in all versions upto and including PostgreSQL 14)
> >
> > datname | stats_reset
> > -----------+-------------------------------
> > | 2023-08-02 06:41:15.777135+00
> > postgres | 2023-08-02 06:41:15.777108+00
> > template1 |
> > template0 |
> > db1 | 2023-08-02 11:02:54.954363+00
> > (5 rows)
> >
> >
> > The problem in PostgreSQL 15 and above
> >
> > datname | stats_reset
> > -----------+------------------------------
> > |
> > postgres |
> > db1 |
> > template1 |
> > template0 |
> > (5 rows)
I agree it's not ideal to reset timestamps only for fixed-numbered
stats. In 13, the timestamp is set to the creation time. There's no
practical issue with doing it that way for now, I think it's
generallynot preferable.
We could use the transaction start time as a sufficient approximation
for the timestamp in fast paths. It might not align with with the
reset time set by pg_stat_reset(), but that shouldn't be a
problem. pgstat_restore_stats runs outside of a transaction, but
GetCurrentTimestamp() is already being used there. The reason for
defining a new function is to improve robustness, although it might
not be necessary.
regards.
--
Kyotaro Horiguchi
NTT Open Source Software Center
Attachment | Content-Type | Size |
---|---|---|
pgstat_set_reset_time_after_crash.patch | text/x-patch | 3.2 KB |
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