Christian, while I agree with you that setting optimizer_features_enable to a back release is not the same as running the optimizer at that release level, this is actually not a good example in this context as complex_view_merging is set to false by optimizer_features_enable=8.1.7 Christian Antognini wrote: > Hi=20 > > >> About the RBO change in 9i, can you show me a test case? > > > E.g. complex_view_merging could lead to different execution plans. > If I run the following statements in 8.1.7 and 9.2.0 I get different = > results... > (notice that both database have a "minimal" INIT.ORA that doesn't modify = > any optimizer parameter) > -- Regards Wolfgang Breitling Centrex Consulting Corporation www.centrexcc.com -- //www.freelists.org/webpage/oracle-l