From: Tom Lane <tgl@sss.pgh.pa.us>
To: pasman pasmański <pasman.p@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Query uses incorrect index
Date: Wed, 22 Dec 2010 10:19:28 -0500
Message-ID: <5209.1293031168@sss.pgh.pa.us> (raw)
In-Reply-To: <AANLkTin5Mrjm48BYXuzLn_atpVN40KvhqjumH15QDLmu@mail.gmail.com>
References: <AANLkTin5Mrjm48BYXuzLn_atpVN40KvhqjumH15QDLmu@mail.gmail.com>
=?ISO-8859-2?Q?pasman_pasma=F1ski?= <pasman.p@gmail.com> writes:
> Thanks for reply.
> I tested random changes and query runs fastest after:
> set seq_page_cost = 0.1;
> set random_page_cost = 0.1;
> cpu_operator_cost = 0.01
As a general rule, "optimizing" those settings on the basis of testing a
single query is a great way to send your overall performance into the
tank --- especially since repeating a single query will be heavily
biased by cache effects. You need to look at a representative sample of
all your queries across all your data.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, pasman.p@gmail.com
Subject: Re: Query uses incorrect index
In-Reply-To: <5209.1293031168@sss.pgh.pa.us>
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