Re: 24.1.5.1. Multixacts And Wraparound

On 2021-Jun-24, Bruce Momjian wrote:

> + As a safety device, an aggressive vacuum scan will
> + occur for any table whose multixact-age (see <xref
> + linkend="vacuum-for-multixact-wraparound"/>) is greater than <xref
> + linkend="guc-autovacuum-multixact-freeze-max-age"/>. Also, if the
> + storage occupied by multixacts exceeds 2GB, aggressive vacuum scans
> + will occur more often for all tables, starting with those that have
> + the oldest multixact-age. Both of these kinds of aggressive scans
> + will occur even if autovacuum is nominally disabled.

This looks good, thanks.

I think "the space occupied by multixacts" is a bit ambiguous -- it is
talking about pg_multixact/members only, but you could interpret that it
talks about both that and pg_multixact/offsets. I'm not sure we need to
be 100% precise about that, so perhaps what you have is sufficient. But
if we do want to be precise, then maybe " ... if the storage occupied by
multixact members (<literal>pg_multixact/members/</literal>) exceeds ..."
covers it.

(At least, that's how I remember this. I don't think things have
changed much since 53bb309d2d5a ...)

--
Álvaro Herrera Valdivia, Chile