Re: patch review, please: Autovacuum/Vacuum times via stats.

From: "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Martijn van Oosterhout <kleptog(at)svana(dot)org>, Larry Rosenman <lrosenman(at)pervasive(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: patch review, please: Autovacuum/Vacuum times via stats.
Date: 2006-05-04 17:38:23
Message-ID: 20060504173823.GL97354@pervasive.com
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On Thu, May 04, 2006 at 01:20:32PM -0400, Tom Lane wrote:
> "Jim C. Nasby" <jnasby(at)pervasive(dot)com> writes:
> > On Wed, May 03, 2006 at 02:25:54PM -0400, Tom Lane wrote:
> >> Isn't this already dealt with by contrib/pg_freespacemap?
>
> > AFAIK that does nothing to tell you how much space is desired by
> > relations.
>
> I thought the latest patch arranged to expose per-relation lastPageCount
> values. If it doesn't then it certainly still needs work.

After CVS-upping... yes, both lastpagecount and nextpage are now
included. But unfortunately the README says next to nothing about what
they mean...

lastpagecount | | Count of pages examined for useful
| | free space.
nextpage | | page index (from 0) to start next
| | search at.

Perhaps if there was some discussion about how the backend used these
two values it would make more sense, but right now I'm not seeing how
lastpagecount relates to how many pages weren't included in the FSM that
should have been...
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461

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