Richard -- You might post the results of "EXPLAIN ANALYZE <your SQL here>;" ... be sure to run it in a transaction if you want to be able roll it back. Perhaps try "EXPLAIN <your SQL>;" first as it is faster, but EXPLAIN ANALYZE shows what the planner is doing. You wrote: > > P.S. Sometimes, some queries seem to benefit from being cancelled and then immediately > re-started. As there are being run in a transaction, I can't see how this could make a difference. > Am I missing anything obvious? Occasionally, a re-start of postgresql-8.4l itself seems to help. This may be the result of caching of the desired rows, either by PostgreSQL or by your operating system. The rollback wouldn't effect this -- the rows are already in memory and not on disk waiting to be grabbed -- much faster on all subsequent queries. HTH, Greg Williamson -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance