Hi Is there a problem with averaging time intervals? I get this error with AVG( inserttime - last) ERROR: Bad interval external representation '0' but SUM( inserttime - last) / COUNT (inserttime) seems to work just fine. Details below, database version is 7.1. thanks, Philip sceppdata=> \d data_chunk Table "data_chunk" Attribute | Type | Modifier ---------------+--------------------------+--------------- chunkid | integer | not null seq_num | integer | channel_dbid | integer | first | timestamp with time zone | first_nanos | integer | first_leapsec | integer | last | timestamp with time zone | last_nanos | integer | last_leapsec | integer | inserttime | timestamp with time zone | default now() Indices: data_chunk__first_idx, data_chunk__last_idx, data_chunk__seq_num_idx, data_chunk_pkey sceppdata=> SELECT AVG( inserttime - last) AS latency FROM data_chunk WHERE channel_dbid = 1 AND last > '2001-06-15 10:35:54.85-04'; ERROR: Bad interval external representation '0' sceppdata=> SELECT SUM( inserttime - last) / COUNT (inserttime) AS latency FROM data_chunk WHERE channel_dbid = 1 AND last > '2001-06-15 10:35:54.85-04'; latency ------------- 00:00:07.07 (1 row) sceppdata=> SELECT inserttime, last, (inserttime - last) AS latency sceppdata-> FROM data_chunk WHERE channel_dbid = 1 AND last > '2001-06-15 10:35:54.85-04'; inserttime | last | latency ------------------------+---------------------------+------------- 2001-06-15 10:37:38-04 | 2001-06-15 10:37:29.70-04 | 00:00:08.30 2001-06-15 10:39:36-04 | 2001-06-15 10:39:30.16-04 | 00:00:05.84 (2 rows) ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly