From: Bruce Momjian <bruce@momjian.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Josh Berkus <josh@agliodbs.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Return of the Solaris vacuum polling problem -- anyone remember this?
Date: Sun, 22 Aug 2010 12:51:47 -0400 (EDT)
Message-ID: <201008221651.o7MGplA28857@momjian.us> (raw)
In-Reply-To: <15870.1282490621@sss.pgh.pa.us>
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 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@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
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To: pgsql-hackers@postgresql.org
Cc: bruce@momjian.us, tgl@sss.pgh.pa.us, josh@agliodbs.com
Subject: Re: Return of the Solaris vacuum polling problem -- anyone remember this?
In-Reply-To: <201008221651.o7MGplA28857@momjian.us>
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