Horton

Re: May be BUG. Periodic burst growth of the checkpoint_req counter on replica.

Alexander Korotkov <aekorotkov@gmail.com>

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From: Alexander Korotkov <aekorotkov@gmail.com>
To: "Anton A. Melnikov" <a.melnikov@postgrespro.ru>
Cc: Magnus Hagander <magnus@hagander.net>, "Anton A. Melnikov" <aamelnikov@inbox.ru>, Andres Freund <andres@anarazel.de>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2024-03-11T09:48:25Z
Lists: pgsql-hackers

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On Mon, Mar 11, 2024 at 5:43 AM Anton A. Melnikov
<a.melnikov@postgrespro.ru> wrote:
> On 11.03.2024 03:39, Alexander Korotkov wrote:
> > Now that we distinguish stats for checkpoints and
> > restartpoints, we need to update the docs.  Please, check the patch
> > attached.
>
> Maybe bring the pg_stat_get_checkpointer_buffers_written() description in consistent with these changes?
> Like that:
>
> --- a/src/include/catalog/pg_proc.dat
> +++ b/src/include/catalog/pg_proc.dat
> @@ -5740 +5740 @@
> -  descr => 'statistics: number of buffers written by the checkpointer',
> +  descr => 'statistics: number of buffers written during checkpoints and restartpoints',

This makes sense.  I've included this into the revised patch.

> And after i took a fresh look at this patch i noticed a simple way to extract
> write_time and sync_time counters for restartpoints too.
>
> What do you think, is there a sense to do this?

I'm not sure we need this.  The ways we trigger checkpoints and
restartpoints are different.  This is why we needed separate
statistics.  But the process of writing buffers is the same.

------
Regards,
Alexander Korotkov

Commits

  1. Improve descriptions of some pg_stat_checkpoints functions in pg_proc.dat.

  2. docs: Enhance the pg_stat_checkpointer view documentation.

  3. Add num_done counter to the pg_stat_checkpointer view.

  4. docs: Improve the description of num_timed column in pg_stat_checkpointer.

  5. Improve documentation for pg_stat_checkpointer fields

  6. Enhance checkpointer restartpoint statistics

  7. Introduce pg_stat_checkpointer