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From: Melanie Plageman <melanieplageman@gmail.com>
Date: Mon, 3 Mar 2025 11:48:18 -0500
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Subject: Re: pgsql: Add relallfrozen to pg_class
To: =?UTF-8?Q?=C3=81lvaro_Herrera?= <alvherre@alvh.no-ip.org>
Cc: pgsql-committers@lists.postgresql.org
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On Mon, Mar 3, 2025 at 11:44=E2=80=AFAM =C3=81lvaro Herrera <alvherre@alvh.=
no-ip.org> wrote:
>
> On 2025-Mar-03, Melanie Plageman wrote:
>
> > relallfrozen, together with relallvisible, is useful for estimating the
> > outstanding number of all-visible but not all-frozen pages in the
> > relation for the purposes of scheduling manual VACUUMs and tuning vacuu=
m
> > freeze parameters.
>
> I'm confused about this.  Why was the new value added to pg_class
> instead of to the pgstat system?  I don't think relallvisible is a good
> precedent, because as you write here, that one is used for planning,
> which has different requirements.  For vacuuming metrics we rely on
> pgstat.

We use relpages and reltuples from pg_class in
relation_needs_vacanalyze() in the same way relallfrozen is being used
here.

If we don't want relallfrozen in pg_class then there is no reason we
wouldn't also move relallvisible out of pg_class too.

- Melanie