Merlin Moncure wrote: > It's pretty easy to craft a query where you're on the winning side, > but what's the worst case of doing two pass...is constant folding a > non trivial fraction of planning time?
One thing that has been suggested is to re-examine the plan after planning is done, and if execution time is estimated to be large (FSVO), then run a second planning pass with more expensive optimizations enabled to try and find better plans. The guiding principle would be to continue to very quickly find good enough plans for frequent/small/simple queries, but spend more planning effort on more complex ones where execution is likely to take much longer than planning time. So doing constant-folding twice would be enabled for the second planning pass. -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
