Yantao Shi <y.shi@xxxxxxxxxxxxx> writes: > testdbspc=# explain select file_name from catalog where file_name like > 'MOD04_L2.A2005311.%.004.2005312013%.hdf'; > QUERY PLAN > Seq Scan on catalog (cost=0.00..429.00 rows=1 width=404) > Filter: (file_name ~~ 'MOD04_L2.A2005311.%.004.2005312013%.hdf'::text) > (2 rows) I'm betting you are using a non-C locale. You need either to run the database in C locale, or to create a special index type that is compatible with LIKE searches. See http://www.postgresql.org/docs/8.1/static/indexes-opclass.html regards, tom lane