Re: Vacuum, analyze, and setting reltuples of pg_class

From: "Jim C(dot) Nasby" <jim(at)nasby(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Greg Sabino Mullane <greg(at)turnstep(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Vacuum, analyze, and setting reltuples of pg_class
Date: 2006-12-13 21:11:12
Message-ID: 20061213211112.GM6551@nasby.net
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On Mon, Dec 11, 2006 at 12:08:30PM -0500, Tom Lane wrote:
> "Greg Sabino Mullane" <greg(at)turnstep(dot)com> writes:
> > Short version: is it optimal for vacuum to always populate reltuples
> > with live rows + dead rows?
>
> If we didn't do that, it would tend to encourage the use of seqscans on
> tables with lots of dead rows, which is probably a bad thing.

So then why does vacuum do that? ISTM that it makes more sense for it to
act the same as analyze and only count live rows.
--
Jim Nasby jim(at)nasby(dot)net
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)

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