On Wednesday 15 July 2009 10:27:50 Craig Ringer wrote: > On Wed, 2009-07-15 at 12:10 +0900, ning wrote: > > First execution: PostgreSQL 0.006277 seconds / DB2 0.009028 seconds > > Second execution: PostgreSQL 0.005932 seconds / DB2 0.000332 seconds > > Actually, on second thoughts that looks a lot like DB2 is caching the > query results and is just returning the cached results when you repeat > the query. Are you sure getting the query *result* is causing the delay? If my faint memory serves right DB2 does plan caching - PG does not. To test this theory you could prepare it and execute it twice. Prepare it: PREPARE test_query AS SELECT void,nameId,tag FROM (SELECT void,nameId,tag,.... FROM Attr WHERE attributeof IN (SELECT oid_ FROM ItemView WHERE ItemView.ItemId=?)) x RIGHT OUTER JOIN (SELECT oid_ FROM ItemView WHERE ItemView.ItemId=? and ItemView.assignedTo_=?) y ON attributeof = oid_ FOR READ ONLY; Execute it: EXECUTE test_query; EXECUTE test_query; Greetings, Andres -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
