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Re: Indexes not always used after inserts/updates/vacuum

From: Reinhard Max <max(at)suse(dot)de>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Michael G(dot) Martin" <michael(at)vpmonline(dot)com>,<pgsql-bugs(at)postgresql(dot)org>
Subject: Re: Indexes not always used after inserts/updates/vacuum
Date: 2002-02-28 15:00:47
Message-ID: Pine.LNX.4.44.0202281555150.9993-200000@Wotan.suse.de (view raw or flat)
Thread:
Lists: pgsql-bugs
On Thu, 28 Feb 2002 at 09:51, Tom Lane wrote:

> Reinhard Max <max(at)suse(dot)de> writes:
> > I've just found a case where forcing indexscans results in much higher
> > speed.
>
> >         ->  Index Scan using foo_pkey on foo
> > 		(cost=0.00..25153.18 rows=352072 width=4)
> > 		(actual time=0.03..157.57 rows=38432 loops=1)
>
> The major estimation error is evidently in this indexscan.  What
> statistics does pg_stats show for this table?

See attached file.

BTW, I've just done the same test on PostgreSQL 7.1 and got similar
results.

cu
	Reinhard

Attachment: pg_stats
Description: text/plain (5.8 KB)

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