> On Tue, Nov 24, 2009 at 2:41 PM, Neil Kodner <nkodner@xxxxxxxxx> wrote: > But all things considered, I can produce the PIO trap time and time again > using 10.2.0.4 OFE. With extensive testing, I've never been able to > reproduce it with 10.1.0. This corresponds to what has been seen from some of your 10046 traces provided: - You'll be able to reproduce longer execution times with 10.2.0.4 OFE because some of the execution plans seem to be suboptimal - obviously caused by the bad cardinality estimates as discussed so far. This will happen when the blocks have to read physically rather than from the cache - so sometimes the execution time will be good, sometimes bad depending on this. - This is probably not reproducible with the 10.1 OFE, since the execution plans tend to be better, due to estimates closer to reality. Even with physical I/O necessary these will perform good, due to significantly less I/O required. Still outstanding: - Setting DENSITY explicitly to get similar cardinality estimates with 10.2.0.4 OFE as with 10.1 OFE - Testing DYNAMIC_SAMPLING on table level Regards, Randolf Oracle related stuff blog: http://oracle-randolf.blogspot.com/ Co-author of the forthcoming "OakTable Expert Oracle Practices" book: http://www.apress.com/book/view/1430226684 http://www.amazon.com/Expert-Oracle-Practices-Database-Administration/dp/1430226684 ______________________________________________________ GRATIS für alle WEB.DE-Nutzer: Die maxdome Movie-FLAT! Jetzt freischalten unter http://movieflat.web.de -- //www.freelists.org/webpage/oracle-l