Received: from maia.hub.org (maia-3.hub.org [200.46.204.243])
	by mail.postgresql.org (Postfix) with ESMTP id 1F3D86336B2
	for <pgsql-performance-postgresql.org@mail.postgresql.org>;
	Tue, 17 Aug 2010 04:26:30 -0300 (ADT)
Received: from mail.postgresql.org ([200.46.204.86])
	by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia,
	port 10024) with ESMTP id 97915-07
	for <pgsql-performance-postgresql.org@mail.postgresql.org>;
	Tue, 17 Aug 2010 07:26:22 +0000 (UTC)
X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6
Received: from gmmr6.centrum.cz (gmmr6.centrum.cz [90.183.38.131])
	by mail.postgresql.org (Postfix) with ESMTP id EF4896336A7
	for <pgsql-performance@postgresql.org>;
	Tue, 17 Aug 2010 04:26:22 -0300 (ADT)
Received: from gmma3 (unknown [90.183.38.133])
	by gmmr6.centrum.cz (Postfix) with ESMTP id E6B014233EC8
	for <pgsql-performance@postgresql.org>;
	Tue, 17 Aug 2010 09:26:19 +0200 (CEST)
Received: from gmmr5.centrum.cz ([127.0.0.1]) by gmma3 (gigamail-antispam);
	Tue, 17 Aug 2010 09:26:20 +0200
Received: from gmmr5.centrum.cz (lb2-self.cent [10.20.11.7])
	by gmma3 (esets_smtp); Tue, 17 Aug 2010 09:26:20 +0200
Received: from mail1002.cent (unknown [90.183.38.132])
	by gmmr5.centrum.cz (Postfix) with SMTP id D73BC80004B3
	for <pgsql-performance@postgresql.org>;
	Tue, 17 Aug 2010 09:26:19 +0200 (CEST)
Received: from localhost by localhost (Centrum Email Forwarder);
	Tue, 17 Aug 2010 09:26:19 +0200
To: <pgsql-performance@postgresql.org>
Subject: Search query is curious
Received: from 80.250.18.198 (X-Forwarded-For: 80.250.18.198)
	by mail1002.centrum.cz (centrum.cz multimail) with HTTP
Date: Tue, 17 Aug 2010 09:26:19 +0200
From: <fiala_marek@centrum.cz>
X-Mailer: Centrum Email 5.3
X-Priority: 3
MIME-Version: 1.0
X-Maser: brud
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Message-Id: <1282029979.831570.27725.nullmailer@mail1002.cent>
X-EsetResult: clean
X-CentrumSpamScore: +66
X-SpamDetected: 0
X-Virus-Scanned: Maia Mailguard 1.0.1
X-Spam-Status: No, hits=-0.01 tagged_above=-10 required=5
	tests=BAYES_20=-0.001, T_RP_MATCHES_RCVD=-0.01, UNPARSEABLE_RELAY=0.001
X-Spam-Level: 
X-Archive-Number: 201008/173
X-Sequence-Number: 40016


Hi,

I've database of lyrics and I'm using this query for suggest box.
SELECT views, title, id FROM songs  WHERE title ILIKE 'bey%' ORDER BY views DESC LIMIT 15;
In query plan is this line:  ->  Seq Scan on songs  (cost=0.00..11473.56 rows=5055 width=23) (actual time=1.088..89.863 rows=77 loops=1)
it takes about 90ms

but when i modify query (remove sort)
SELECT views, title, id FROM songs  WHERE title ILIKE 'bey%' LIMIT 15;
In query plan ->  Seq Scan on songs  (cost=0.00..11473.56 rows=5055 width=23) (actual time=1.020..20.601 rows=15 loops=1
seq scan takes only 20ms now, why?

Or any suggestion to optimize this query?
In table songs are about 150.000 rows.

Thank you for your reply.

Best regards.
Marek Fiala