Re: pgsql: Add relallfrozen to pg_class

On Mon, Mar 3, 2025 at 11:44 AM Álvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)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 vacuum
> > 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