Re: 24.1.5.1. Multixacts And Wraparound

On Thu, Jun 24, 2021 at 04:06:38PM -0400, Álvaro Herrera wrote:
> 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 ...)

OK, I got "members" into the doc section and applied it to master and PG
14.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

If only the physical world exists, free will is an illusion.