From: Gregory Stark <stark@enterprisedb.com>
To: weiping <laserlist@pgsqldb.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: different query plan because different limit # (Re: weird query plan)
Date: Wed, 06 Jun 2007 10:21:59 +0100
Message-ID: <87ejkph1zc.fsf@oxford.xeocode.com> (raw)
In-Reply-To: <46666128.7050500@pgsqldb.com>
References: <46662DE7.4030602@pgsqldb.com>
<46663114.3000501@pgsqldb.com>
<46666128.7050500@pgsqldb.com>
"weiping" <laserlist@pgsqldb.com> writes:
> -> Index Scan using urlusermaps_userid on wd_urlusermaps
> (cost=0.00..6750.55 rows=1094 width=4) (actual time=1.478..16.563 rows=41 loops=1)
> Index Cond: (userid = 219177)
> Filter: ("share" = 1)
It's estimating 1094 rows and getting 41 rows. You might considering raising
the statistics target for that table.
Does it get accurate estimates for the number of rows for each of these?
explain analyze select * from wd_urlusermaps where userid=219177
explain analyze select * from wd_urlusermaps where share=1
(the latter might take a while)
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
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To: pgsql-performance@postgresql.org
Cc: stark@enterprisedb.com, laserlist@pgsqldb.com
Subject: Re: different query plan because different limit # (Re: weird query plan)
In-Reply-To: <87ejkph1zc.fsf@oxford.xeocode.com>
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