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To: Ryan Holmes <ryan@hyperstep.com>
cc: pgsql-performance@postgresql.org
Subject: Re: IN operator causes sequential scan (vs. multiple OR expressions) 
In-reply-to: <AE23623B-65E0-4CC8-8F7E-3920E4B42FDC@hyperstep.com> 
References: <AE23623B-65E0-4CC8-8F7E-3920E4B42FDC@hyperstep.com>
Comments: In-reply-to Ryan Holmes <ryan@hyperstep.com>
	message dated "Sat, 27 Jan 2007 15:34:56 -0800"
Date: Sat, 27 Jan 2007 18:53:06 -0500
Message-ID: <24016.1169941986@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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Ryan Holmes <ryan@hyperstep.com> writes:
> I have a relatively simple query where the planner chooses a  
> sequential scan when using the IN operator but chooses an index scan  
> when using logically equivalent multiple OR expressions.

EXPLAIN ANALYZE for both, please?

If you set enable_seqscan = off, does that force an indexscan, and if so
what does EXPLAIN ANALYZE show in that case?

			regards, tom lane