=> set enable_indexscan = on; SET => set enable_seqscan = off; SET => EXPLAIN select distinct comp_code, supp_code, supp_name, buyer_code, buyer_name, item_code, revision, description, po_no, pos_no, order_date, delivery_date, reschedule_date, reschedule_qty, ordered_qty, delivered_qty, backorder_qty, stock, warehouse_code, allocated, exception, run_date from reschedule_bak where order_date = '01/04/2003'; QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Unique (cost=6999.59..7123.48 rows=215 width=213) -> Sort (cost=6999.59..7004.98 rows=2155 width=213) Sort Key: comp_code, supp_code, supp_name, buyer_code, buyer_name, item_code, revision, description, po_no, pos_no, order_date, delivery_date, reschedule_date, reschedule_qty, ordered_qty, delivered_qty, backorder_qty, stock, warehouse_code, allocated, exception, run_date -> Index Scan using reschedule_bak_order_date_idx on reschedule_bak (cost=0.00..6880.30 rows=2155 width=213) Index Cond: (order_date = '01/04/2003'::date) (5 rows) => EXPLAIN select distinct comp_code, supp_code, supp_name, buyer_code, buyer_name, item_code, revision, description, po_no, pos_no, order_date, delivery_date, reschedule_date, reschedule_qty, ordered_qty, delivered_qty, backorder_qty, stock, warehouse_code, allocated, exception, run_date from reschedule_bak where order_date >= '01/04/2003'; QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Unique (cost=659460.84..678797.48 rows=33629 width=213) -> Sort (cost=659460.84..660301.57 rows=336289 width=213) Sort Key: comp_code, supp_code, supp_name, buyer_code, buyer_name, item_code, revision, description, po_no, pos_no, order_date, delivery_date, reschedule_date, reschedule_qty, ordered_qty, delivered_qty, backorder_qty, stock, warehouse_code, allocated, exception, run_date -> Index Scan using reschedule_bak_order_date_idx on reschedule_bak (cost=0.00..587396.88 rows=336289 width=213) Index Cond: (order_date >= '01/04/2003'::date) (5 rows) =>\q 2003-12-20 10:35:10 [1558] LOG: query: set enable_seqscan = on; 2003-12-20 10:35:10 [1558] LOG: duration: 0.000458 sec 2003-12-20 10:36:57 [1558] LOG: query: select distinct comp_code, supp_code, supp_name, buyer_code, buyer_name, item_code, revision, description, po_no, pos_no, order_date, delivery_date, reschedule_date, reschedule_qty, ordered_qty, delivered_qty, backorder_qty, stock, warehouse_code, allocated, exception, run_date from reschedule_bak where order_date >= '01/04/2003'; 2003-12-20 10:47:15 [1558] LOG: duration: 617.886026 sec 2003-12-20 11:11:37 [1558] LOG: query: set enable_seqscan = off; 2003-12-20 11:11:37 [1558] LOG: duration: 0.000458 sec 2003-12-20 11:11:40 [1558] LOG: query: select distinct comp_code, supp_code, supp_name, buyer_code, buyer_name, item_code, revision, description, po_no, pos_no, order_date, delivery_date, reschedule_date, reschedule_qty, ordered_qty, delivered_qty, backorder_qty, stock, warehouse_code, allocated, exception, run_date from reschedule_bak where order_date >= '01/04/2003'; 2003-12-20 11:22:04 [1558] LOG: duration: 623.982111 sec