Tom Lane wrote:
> Bruce Momjian <bruce@momjian.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 toprevent 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@momjian.us> http://momjian.us EnterpriseDB
http://enterprisedb.com
+ It's impossible for everything to be true. +
