Re: Correlation in cost_index()

From: Manfred Koizar <mkoi-pg(at)aon(dot)at>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Correlation in cost_index()
Date: 2002-10-03 07:09:49
Message-ID: 3mpnpuccoukikseed1e3pedo5t1dfj64cn@4ax.com
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On Wed, 02 Oct 2002 18:48:49 -0400, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
wrote:
>I don't think it's really a good idea to expect users to pick among
>multiple cost functions

The idea is that PG is shipped with a default representing the best of
our knowledge and users are not encouraged to change it. When a user
sends a "PG does not use my index" or "Why doesn't it scan
sequentially?" message to one of the support lists, we advise her/him
to set index_cost_algorithm to 3 (or whatever we feel appropriate) and
watch the feedback we get.

We don't risk anything, if the default is the current behaviour.

Servus
Manfred

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