To: "Chris Cox" <cjcox@optushome.com.au>
Cc: pgsql-sql@postgresql.org
Subject: Re: LIKE on index not working 
In-reply-to: <030e01c46fbe$e8baeb90$5100000a@PHOENIX> 
References: <030e01c46fbe$e8baeb90$5100000a@PHOENIX>
Comments: In-reply-to "Chris Cox" <cjcox@optushome.com.au>
	message dated "Thu, 22 Jul 2004 17:38:28 +1000"
Date: Thu, 22 Jul 2004 13:10:38 -0400
Message-ID: <10467.1090516238@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

"Chris Cox" <cjcox@optushome.com.au> writes:
> For some reason I just can't get this to use the index for the following
> query.  I'm using PostgreSQL 7.3.4.

It works for me in 7.3.6 (see below).  I'd guess that you are using a
non-LIKE-safe locale setting --- can you get LIKE to use indexes at
all?

regression=# create table fooey(f1 varchar);
CREATE TABLE
regression=# create index fooeyi on fooey(lower(f1));
CREATE INDEX
regression=# explain select * from fooey where lower(f1) = lower('z');
                              QUERY PLAN
----------------------------------------------------------------------
 Index Scan using fooeyi on fooey  (cost=0.00..17.08 rows=5 width=32)
   Index Cond: (lower((f1)::text) = 'z'::text)
(2 rows)

regression=# explain select * from fooey where lower(f1) like lower('z');
                              QUERY PLAN
----------------------------------------------------------------------
 Index Scan using fooeyi on fooey  (cost=0.00..17.08 rows=5 width=32)
   Index Cond: (lower((f1)::text) = 'z'::text)
   Filter: (lower((f1)::text) ~~ 'z'::text)
(3 rows)


			regards, tom lane