Randall Skelton <skelton@brutus.uwaterloo.ca> writes: > As you suggested, while this is much shorter in length, it is > considerably longer in execution. >> SELECT t1.timestamp FROM ( >> SELECT timestamp FROM cal_quat_1 UNION >> SELECT timestamp FROM cal_quat_2 UNION >> SELECT timestamp FROM cal_quat_3 UNION >> SELECT timestamp FROM cal_quat_4 UNION >> SELECT timestamp FROM cal_ccd_temp >> ) t1 WHERE >> t1.timestamp BETWEEN '2004-02-01 00:03:30' AND '2004-02-01 >> 00:04:00'; Do you actually need UNION, or would UNION ALL do? (The latter doesn't try to eliminate duplicates.) regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org