"IOS scan" ? Index Only Scan What's your seq_page_cost and random_page_cost? hashes=# SELECT name, setting, reset_val FROM pg_settings WHERE setting <> reset_val; name | setting | reset_val -------------------------+----------------+----------- archive_command | (disabled) | enable_bitmapscan | off | on enable_indexscan | off | on enable_seqscan | off | on log_file_mode | 0600 | 384 random_page_cost | 0.1 | 4 seq_page_cost | 0.1 | 1 transaction_isolation | read committed | default unix_socket_permissions | 0777 | 511 (9 rows) Postgresql 9.2.1 was configured and built with default settings. Thank you. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance