Received: from localhost (maia-1.hub.org [200.46.204.191])
	by postgresql.org (Postfix) with ESMTP id E09E29F9D8B
	for <pgsql-sql-postgresql.org@postgresql.org>;
	Thu,  9 Aug 2007 22:35:31 -0300 (ADT)
Received: from postgresql.org ([200.46.204.71])
	by localhost (mx1.hub.org [200.46.204.191]) (amavisd-maia, port 10024)
	with ESMTP id 49929-04 for <pgsql-sql-postgresql.org@postgresql.org>;
	Thu,  9 Aug 2007 22:35:25 -0300 (ADT)
X-Greylist: from auto-whitelisted by SQLgrey-1.7.5
Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130])
	by postgresql.org (Postfix) with ESMTP id 2D7B89F9CB3
	for <pgsql-sql@postgresql.org>; Thu,  9 Aug 2007 22:35:26 -0300 (ADT)
Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1])
	by sss.pgh.pa.us (8.14.1/8.14.1) with ESMTP id l7A1ZDoI007475;
	Thu, 9 Aug 2007 21:35:14 -0400 (EDT)
To: Andreas Joseph Krogh <andreak@officenet.no>
cc: pgsql-sql@postgresql.org,
	"Rodrigo De =?utf-8?q?Le=C3=B3n?=" <rdeleonp@gmail.com>
Subject: Re: PG won't use index on ORDER BY <expression> 
In-reply-to: <200708092310.53309.andreak@officenet.no> 
References: <200708092018.44111.andreak@officenet.no>
	<200708092238.46284.andreak@officenet.no>
	<a55915760708091357m4632c952s10bdafd235765941@mail.gmail.com>
	<200708092310.53309.andreak@officenet.no>
Comments: In-reply-to Andreas Joseph Krogh <andreak@officenet.no>
	message dated "Thu, 09 Aug 2007 23:10:52 +0200"
Date: Thu, 09 Aug 2007 21:35:13 -0400
Message-ID: <7474.1186709713@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
X-Virus-Scanned: Maia Mailguard 1.0.1
X-Archive-Number: 200708/62
X-Sequence-Number: 29000

Andreas Joseph Krogh <andreak@officenet.no> writes:
> I forgot to mention: I use UTF-8. IIRC, it works fine with C-locale without
> the "varchar_pattern_ops", which is why it works for you I think.

That shouldn't make any difference, and doesn't for me in testing here:

regression=# select version();
                                                  version                                                  
-----------------------------------------------------------------------------------------------------------
 PostgreSQL 8.2.4 on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.1.2 20070626 (Red Hat 4.1.2-13)
(1 row)

regression=# show lc_collate;
 lc_collate 
------------
 en_US.utf8
(1 row)

regression=# show server_encoding ;
 server_encoding 
-----------------
 UTF8
(1 row)

regression=# \d person
                                Table "public.person"
  Column   |       Type        |                      Modifiers                      
-----------+-------------------+-----------------------------------------------------
 id        | integer           | not null default nextval('person_id_seq'::regclass)
 firstname | character varying | 
 lastname  | character varying | 
Indexes:
    "person_pkey" PRIMARY KEY, btree (id)
    "person_lowerfullname_idx" btree ((lower(COALESCE(firstname, ''::character varying)::text) || lower(COALESCE(lastname, ''::character varying)::text)))

regression=# explain select id from person order by (lower(COALESCE(firstname, '')) ||  lower(COALESCE(lastname, ''))) ASC limit 1;
                                           QUERY PLAN                                            
-------------------------------------------------------------------------------------------------
 Limit  (cost=0.00..0.08 rows=1 width=68)
   ->  Index Scan using person_lowerfullname_idx on person  (cost=0.00..62.25 rows=800 width=68)
(2 rows)


So there's something going on that you haven't told us about your installation.

			regards, tom lane