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Re: Performance problem on RH7.1

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: csegyud(at)vnet(dot)hu
Cc: "'Alvaro Herrera'" <alvherre(at)dcc(dot)uchile(dot)cl>,"'Pgsql-General(at)Postgresql(dot)Org (E-mail)'" <pgsql-general(at)postgresql(dot)org>
Subject: Re: Performance problem on RH7.1
Date: 2004-06-29 05:52:24
Message-ID: 24415.1088488344@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-general
=?iso-8859-2?Q?Egy=FCd_Csaba?= <csegyud(at)vnet(dot)hu> writes:
> Limit  (cost=30.28..30.28 rows=1 width=58) (actual time=0.19..0.19 rows=1
> loops=1)
>   ->  Sort  (cost=30.28..30.30 rows=7 width=58) (actual time=0.18..0.18
> rows=2 loops=1)
>         Sort Key: stockid, productid, changeid, date, "time"
>         ->  Index Scan using t_stockchanges_fullindex on t_stockchanges
> (cost=0.00..30.18 rows=7 width=58) (actual time=0.04..0.08 rows=6 loops=1)
>               Index Cond: ((stockid = 1) AND (productid = 234) AND (changeid
> = 1) AND (date <= '2004.06.29'::bpchar))
> Total runtime: 0.25 msec
> ( Compared to 9.17 msec !!!! 37 times faster! )

Good, but you're not there yet --- the Sort step shouldn't be there at
all.  You've still got some inconsistency between the ORDER BY and the
index.  Check my example again.

			regards, tom lane

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