From: Bruce Momjian <bruce@momjian.us>
Message-Id: <201008221404.o7ME49628565@momjian.us>
Subject: Re: Return of the Solaris vacuum polling problem --
	anyone remember this?
In-Reply-To: <AANLkTik5_oyMq+Ep74CC9GMjf_uBe8CPuY1775F1p=tJ@mail.gmail.com>
To: Rob Wultsch <wultsch@gmail.com>
Date: Sun, 22 Aug 2010 10:04:09 -0400 (EDT)
CC: Josh Berkus <josh@agliodbs.com>, Tom Lane <tgl@sss.pgh.pa.us>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset="US-ASCII"

Rob Wultsch wrote:
> For a documentation patch should this not be back ported to all
> relevant versions?

It is only a minor adjustment and I normally don't backpatch that.

---------------------------------------------------------------------------


> 
> On 8/21/10, Bruce Momjian <bruce@momjian.us> wrote:
> > Josh Berkus wrote:
> >>
> >> > On further reflection, though: since we put in the BufferAccessStrategy
> >> > code, which was in 8.3, the background writer isn't *supposed* to be
> >> > very much involved in writing pages that are dirtied by VACUUM.  VACUUM
> >> > runs in a small ring of buffers and is supposed to have to clean its own
> >> > dirt most of the time.  So it's wrong to blame this on the bgwriter not
> >> > holding up its end.  Rather, what you need to be thinking about is how
> >> > come vacuum seems to be making lots of pages dirty on only one of these
> >> > machines.
> >>
> >> This is an anti-wraparound vacuum, so it could have something to do with
> >> the hint bits.  Maybe it's setting the freeze bit on every page, and
> >> writing them one page at a time?  Still don't understand the call to
> >> pollsys, even so, though.
> >
> > 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.
> >
> > --
> >   Bruce Momjian  <bruce@momjian.us>        http://momjian.us
> >   EnterpriseDB                             http://enterprisedb.com
> >
> >   + It's impossible for everything to be true. +
> >
> 
> 
> -- 
> Rob Wultsch
> wultsch@gmail.com

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

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