Re: Query plan and sub-queries

From: Steve Heaven <steve(at)thornet(dot)co(dot)uk>
To: Mike Mascari <mascarm(at)mascari(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Query plan and sub-queries
Date: 2000-08-08 12:47:34
Message-ID: 3.0.1.32.20000808134734.00700ed4@mail.thornet.co.uk
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At 08:24 08/08/00 -0400, you wrote:
> A workaround is to replace IN with EXISTS:

This still does a sequential rather that indexed scan:

explain select * from books_fti where exists
(select R1684.stockno from R1684,books_fti where
R1684.stockno=books_fti.stockno );

Result (cost=79300.27 rows=0 width=0)
InitPlan
-> Nested Loop (cost=2093.00 rows=1024706 width=24)
-> Seq Scan on r1684 (cost=43.00 rows=1000 width=12)
-> Index Scan using allbooks_isbn on books_fti (cost=2.05
rows=1024705 width=12)
-> Seq Scan on books_fti (cost=79300.27 rows=1024705 width=160)

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