Received: from localhost (postgresql.org [64.49.215.8])
	by postgresql.org (Postfix) with ESMTP id B5A51475EB4
	for <pgsql-sql@postgresql.org>; Sat, 16 Nov 2002 14:02:33 -0500 (EST)
Received: from davinci.ethosmedia.com (davinci.ethosmedia.com [209.10.40.250])
	by postgresql.org (Postfix) with ESMTP id 159A4475E24
	for <pgsql-sql@postgresql.org>; Sat, 16 Nov 2002 14:02:33 -0500 (EST)
Received: from [63.195.55.98] (account <josh@agliodbs.com>)
	by davinci.ethosmedia.com (CommuniGate Pro WebUser 3.5.9)
	with HTTP id 1829092; Sat, 16 Nov 2002 11:06:20 -0800
From: "Josh Berkus" <josh@agliodbs.com>
Subject: Re: INDEX PROBLEMS ?
To: PostgreSQL Server <postgres@rsd.it>, pgsql-sql@postgresql.org
X-Mailer: CommuniGate Pro Web Mailer v.3.5.9
Date: Sat, 16 Nov 2002 11:06:20 -0800
Message-ID: <web-1829092@davinci.ethosmedia.com>
In-Reply-To: 
 <Pine.LNX.4.44.0211161901570.8254-100000@sunrise2.radiostudiodelta.it>
MIME-Version: 1.0
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 8bit
X-Virus-Scanned: by AMaViS new-20020517
X-Archive-Number: 200211/241
X-Sequence-Number: 10383

Alex,

> On postgres 7.2.3 I have found what follows:
> 
> explain select * from documents where iddoc>1;
> 
> Seq Scan on lotti  (cost=0.00..831.79 rows=26783 width=98)
> 
> EXPLAIN
> explain select * from documents where iddoc=1;
> 
> Index Scan using lotti_pkey on lotti  (cost=0.00..2.26 rows=1
> width=98)
> 
> Why index is not used for operators > and < ????

Because ">" is returning 26,000 rows.   When you return that many rows,
a Seq Scan is faster.

-Josh