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Re: problem with pg_statistics

From: Manfred Koizar <mkoi-pg(at)aon(dot)at>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Andre Schubert <andre(at)km3(dot)de>, pgsql-performance(at)postgresql(dot)org
Subject: Re: problem with pg_statistics
Date: 2003-06-26 15:51:56
Message-ID: h64mfv8quqjc19dv0ufm9oegj6p1rpeipp@4ax.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Thu, 26 Jun 2003 10:08:05 -0400, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
wrote:
>Andre Schubert <andre(at)km3(dot)de> writes:
>> i think i need a little help with a problem with pg_statistic.
>
>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.

Andre might also want to experiment with effective_cache_size and with
ALTER TABLE ... SET STATISTICS.

Or there's something wrong with correlation?

Andre, what hardware is this running on?  What are the values of
shared_buffers, random_page_cost, effective_cache_size, ... ?  Could
you show us the result of

	SELECT * FROM pg_stats
	 WHERE tablename = "tbl_traffic" AND attname = "time_stamp";

Servus
 Manfred

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Subject: Re: problem with pg_statistics
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