Received: from lin.local.lan ([216.221.221.2])
	by mail.postgresql.org (8.11.1/8.11.1) with ESMTP id f0VGvUq52836
	for <pgsql-sql@postgresql.org>; Wed, 31 Jan 2001 11:57:30 -0500 (EST)
	(envelope-from najm@mondo-live.com)
Received: from mondo-live.com (IDENT:najm@ll20.local2.lan [192.168.2.20])
	by lin.local.lan (8.9.3/8.8.7) with ESMTP id PAA03913
	for <pgsql-sql@postgresql.org>; Wed, 31 Jan 2001 15:51:41 GMT
Message-ID: <3A7996AC.AD99A45B@mondo-live.com>
Date: Thu, 01 Feb 2001 12:02:36 -0500
From: Najm Hashmi <najm@mondo-live.com>
X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.2.14-5.0 i686)
X-Accept-Language: en
MIME-Version: 1.0
To: "pgsql-sql@postgresql.org" <pgsql-sql@postgresql.org>
Subject: Index scan
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Archive-Number: 200101/483
X-Sequence-Number: 1159

Hi all,
 I  am unable to understand why  my inidcies are not  used in the query.
I have following indices:
index on categories.root
index on media.category
unique index on categories.id
 Here is my query :
mondo=# explain select m.id
                   form media m, categories c
                    where c.id=m.category and c.root like 'B%';
NOTICE:  QUERY PLAN:

Hash Join  (cost=22.55..116.80 rows=11 width=28)
  ->  Seq Scan on media m  (cost=0.00..60.40 rows=840 width=16)
  ->  Hash  (cost=22.50..22.50 rows=20 width=12)
        ->  Index Scan using cat_id_root on categories c
(cost=0.00..22.50 rows=20 width=12)
EXPLAIN

 I simply dont understand why it uses seq scan on media.
Thanks all for your help.
-Najm