thanks for the hint, now the peak hour is over and the same scan is taking 71 ms in place of 80000 ms and the total query time is also acceptable. But it is surprising that the scan was taking so long consistently at that point of time. I shall test again under similar circumstance tomorrow. Is it possible to enable block level statistics from the psql prompt for a particular query and see the results on the psql prompt ? explain analyze SELECT count(*) from rfi_partitions.rfis_part_2006_02 where generated_date >= 2251 and receiver_uid=1320721 ; QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------------------------------------ Aggregate (cost=6.44..6.45 rows=1 width=0) (actual time=71.513..71.513 rows=1 loops=1) -> Index Scan using rfis_part_2006_02_generated_date on rfis_part_2006_02 (cost=0.00..6.43 rows=1 width=0) (actual time=71.508..71.508 rows=0 loops=1) Index Cond: (generated_date >= 2251) Filter: (receiver_uid = 1320721) Total runtime: 71.553 ms (5 rows) -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance