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Re: problem with pg_statistics

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Manfred Koizar <mkoi-pg(at)aon(dot)at>
Cc: Andre Schubert <andre(at)km3(dot)de>, pgsql-performance(at)postgresql(dot)org
Subject: Re: problem with pg_statistics
Date: 2003-06-26 16:03:52
Message-ID: 25814.1056643432@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
Manfred Koizar <mkoi-pg(at)aon(dot)at> writes:
> On Thu, 26 Jun 2003 10:08:05 -0400, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
> wrote:
>> Try reducing random_page_cost

> With index scan cost being more than 25 * seq scan cost, I guess that
> - all other things held equal - even random_page_cost = 1 wouldn't
> help.

Oh, you're right, I was comparing the wrong estimated costs.  Yeah,
changing random_page_cost won't fix it.

> Or there's something wrong with correlation?

That seems like a good bet.  Andre, is this table likely to be
physically ordered by time_stamp, or nearly so?  If so, do you
expect that condition to persist, or is it just an artifact of
a test setup?

			regards, tom lane

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