Re: Return of the Solaris vacuum polling problem -- anyone remember this?

Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > We often mention that we do vacuum freeze for anti-wraparound vacuum,
> > but not for pg_clog file removal, which is the primary trigger for
> > autovacuum vacuum freezing. I have added the attached documentation
> > patch for autovacuum_freeze_max_age; back-patched to 9.0.
>
> This patch does not actually seem like an improvement. The paragraph is
> all about transaction age, but you've inserted something entirely
> unrelated, and not only that but chosen to make the unrelated thing seem
> like the major consequence and anti-wraparound an afterthought.

Well, the reason that value is 200 million is for pg_clog cleanup, not
for xid wraparound protection. The next sentence does relate to xid
wraparound, but it seems to fit because the previous sentence ends with
xid wraparound:

Note that the system will launch autovacuum processes to
prevent wraparound even when autovacuum is otherwise disabled.

If we were worried about just xid wraparound I assume the value would be
2 billion.

Do you have a suggestion? Reorder the items?

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

+ It's impossible for everything to be true. +