Re: Index Scans become Seq Scans after VACUUM ANALYSE

From: "Luis Alberto Amigo Navarro" <lamigo(at)atc(dot)unican(dot)es>
To: <pgsql-hackers(at)postgresql(dot)org>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Index Scans become Seq Scans after VACUUM ANALYSE
Date: 2002-04-17 07:30:08
Message-ID: 00a001c1e5e1$b3fc8e40$cab990c1@atc.unican.es
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> > On Wed, 2002-04-17 at 06:51, mlw wrote:
> > > I just think there is sufficient evidence to suggest that if a DBA
creates an
> > > index, there is strong evidence (better than statistics) that the
index need be
> > > used. In the event that an index exists, there is a strong indication
that,
> > > without overwhelming evidence, that the index should be used. You have
admitted
> > > that statistics suck, but the existence of an index must weight
(heavily) on
> > > the evaluation on whether or not to use an index.

On my own few experience I think this could be solved decreasing
random_page_cost, if you would prefer to use indexes than seq scans, then
you can lower random_page_cost to a point in which postgres works as you
want. So the planner would prefer indexes when in standard conditions it
would prefer seq scans.

Regards

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