Carlos Henrique Reimer wrote: > We're facing a weird performance problem in one of our PostgreSQL servers running 8.0.26. Ouch. 8.0 has been out of support since October 2010, and I am afraid that might be a problem for you. > What can explain the difference between calling same query inside and outside a cursor? If we run the > query outside a cursor we got a response time of 755ms and 33454ms if we call the same query inside a > cursor. The planner estimates that only 10% of the rows from the cursor will be fetched. That favors plan that deliver the first rows quickly. This percentage has been added as a configuration parameter in 8.4 (cursor_tuple_fraction). You would set this parameter to 1.0 to get the same plans with or without cursors. > I suspect the query called inside the cursor is using a different plan than the same query outside a > cursor. Is there a way to confirm this suspicion? You could try EXPLAIN DECLARE cur1 CURSOR FOR .... Yours, Laurenz Albe -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
