From: Josh Berkus <josh@agliodbs.com>
To: Aaron Held <aaron@MetroNY.com>
To: Chris Ruprecht <chrup@earthlink.net>
To: pgsql-sql@postgresql.org
Subject: Re: Performance w/ multiple WHERE clauses
Date: Fri, 20 Sep 2002 14:55:30 -0700
Message-ID: <200209201455.30054.josh@agliodbs.com> (raw)
In-Reply-To: <3D8B2C02.8020904@MetroNY.com>
References: <5.1.1.6.2.20020918111926.00a82058@mail.nashlinux.com>
<200209182039.59437.chrup@earthlink.net>
<3D8B2C02.8020904@MetroNY.com>
Aaron,
> # SET enable_seqscan to FALSE ;
> forced the use of an Index and sped things up greatly.
>
> I am not sure why it made the switch. The load on the server seems to
> affect the performance, but I am seeing it more on the production server
> with 100 million rows as opposed to the development server with only
> about 6 million. I need to buy more drives and develop on a larger data
> set.
What version are you using?
I'd have 3 suggestions:
1) ANALYZE, ANALYZE, ANALYZE. Then check if the row estimates made by EXPLAIN
seem accurate.
2) Modify your postgresql.conf file to raise the cost of seq_scans for parser
estimates.
3) Test this all again when 7.3 comes out, as parser estimate improves all the
time.
--
-Josh Berkus
Aglio Database Solutions
San Francisco
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To: pgsql-sql@postgresql.org
Cc: josh@agliodbs.com, aaron@MetroNY.com, chrup@earthlink.net
Subject: Re: Performance w/ multiple WHERE clauses
In-Reply-To: <200209201455.30054.josh@agliodbs.com>
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