Re: doc: New cumulative stats subsystem obsoletes comment in maintenance.sgml

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Andres Freund <andres(at)anarazel(dot)de>
Subject: Re: doc: New cumulative stats subsystem obsoletes comment in maintenance.sgml
Date: 2022-07-14 22:58:09
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On Wed, Apr 20, 2022 at 04:40:44PM -0700, David G. Johnston wrote:
> Hackers,
> The new cumulative stats subsystem no longer has a "lost under heavy load"
> problem so that parenthetical should go (or at least be modified).
> These stats can be reset so some discussion about how the system uses them
> given that possibility seems like it would be good to add here.  I'm not sure
> what that should look like though.
> diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
> index 04a04e0e5f..360807c8f9 100644
> --- a/doc/src/sgml/maintenance.sgml
> +++ b/doc/src/sgml/maintenance.sgml
> @@ -652,9 +652,8 @@ vacuum insert threshold = vacuum base insert threshold +
> vacuum insert scale fac
>      tuples to be frozen by earlier vacuums.  The number of obsolete tuples and
>      the number of inserted tuples are obtained from the cumulative statistics
> system;
>      it is a semi-accurate count updated by each <command>UPDATE</command>,
> -    <command>DELETE</command> and <command>INSERT</command> operation.  (It is
> -    only semi-accurate because some information might be lost under heavy
> -    load.)  If the <structfield>relfrozenxid</structfield> value of the table
> +    <command>DELETE</command> and <command>INSERT</command> operation.
> +    If the <structfield>relfrozenxid</structfield> value of the table
>      is more than <varname>vacuum_freeze_table_age</varname> transactions old,
>      an aggressive vacuum is performed to freeze old tuples and advance
>      <structfield>relfrozenxid</structfield>; otherwise, only pages that have
> been modified

Yes, I agree and plan to apply this patch soon.

Bruce Momjian <bruce(at)momjian(dot)us>

Indecision is a decision. Inaction is an action. Mark Batterson

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