I'm not sure how well this works in Postgres. For Informix, we could trick the optimizer into using an index with something like:
Select colname from table where colname !=NULL. Specifically mentioning the column in the query was the trick. In esql/C, there were return parameters that then told you how many rows were found. >CREATE INDEX st_v_state_idx ON state_tst USING btree (v_state); >CREATE INDEX st_f_state_idx ON state_tst USING btree (f_state); > >Load the table using a copy from ... > >vacuum verbose analyze state_tst; > >Total rows: 14309241 > >Queries using either f_state = or v_state = explain (and appear to >execute) using a sequential scan. Resulting in 60 - 80 second query >times. > >Can I force the use of an index? Or do I have something wrong? Any >ideas? > >pg_test=# explain select count(*) from state_tst where f_state = 'PA'; >NOTICE: QUERY PLAN: > >Aggregate (cost=277899.65..277899.65 rows=1 width=0) > -> Seq Scan on state_tst (cost=0.00..277550.51 rows=139654 > width=0) > >EXPLAIN > >---------------------------(end of broadcast)--------------------------- >TIP 4: Don't 'kill -9' the postmaster ---------------------------(end of broadcast)--------------------------- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])