From: Dennis Bjorklund <db@zigo.dhs.org>
To: Rolf Østvik <rolfostvik@yahoo.no>
Cc: pgsql-performance@postgresql.org
Subject: Re: Worse perfomance on 8.2.0 than on 7.4.14
Date: Sun, 31 Dec 2006 16:27:12 +0100
Message-ID: <4597D6D0.8010902@zigo.dhs.org> (raw)
In-Reply-To: <200612311233.10201.rolfostvik@yahoo.no>
References: <200612311233.10201.rolfostvik@yahoo.no>
Rolf Østvik skrev:
> I have a simple query which uses 32ms on 7.4.14 and 1015ms on 8.2.0.
> I guess 7.4.14 creates a better execution plan than 8.2.0 for this query but
Try to turn off planner options in 8.2 to make it generate the same plan
as 7.4. Then run EXPLAIN ANALYZE on that query that generate the same
plan as in 7.4 and we can compare the costs and maybe understand what go
wrong.
For example, try
set enable_hashjoin to false;
set enable_bitmapscan to false;
but you might need to turn off more things to get it to generate the 7.4
plan.
/Dennis
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: db@zigo.dhs.org, rolfostvik@yahoo.no
Subject: Re: Worse perfomance on 8.2.0 than on 7.4.14
In-Reply-To: <4597D6D0.8010902@zigo.dhs.org>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox