How to use index in case insensitive substing search - Mailing list pgsql-general

How to force postgres to use index for the following query (I can change the
query to equivalent if required)

select nimi from klient where lower(nimi) like 'test%'

Currently it does NOT use index:

create index nimib2 on firma1.klient(lower(nimi) bpchar_pattern_ops);
explain analyze select nimi from firma1.klient where lower(nimi) like
'mokter%'

"Seq Scan on klient  (cost=0.00..9.79 rows=1 width=74) (actual
time=0.740..0.761 rows=1 loops=1)"
"  Filter: (lower((nimi)::text) ~~ 'mokter%'::text)"
"Total runtime: 0.877 ms"

Postgres 8.1 UTF8 encoding in Windows XP

Note.

Query

explain analyze select nimi from firma1.klient where nimi like 'Mokter%'

for same data uses index:

"Index Scan using nimib on klient  (cost=0.00..5.80 rows=1 width=74) (actual
time=9.402..9.427 rows=1 loops=1)"
"  Index Cond: ((nimi ~>=~ 'Mokter'::bpchar) AND (nimi ~<~
'Moktes'::bpchar))"
"  Filter: (nimi ~~ 'Mokter%'::text)"
"Total runtime: 9.615 ms"

Andrus.