Very nice summation, Martic. As to your statement below, it would be a good start if Oracle had separate system statistics for each instance in a RAC cluster. At 11:43 PM 5/20/2005, Martic Zoran wrote: >Oracle will maybe evolve into having system statistics >per object or at least per file/disk. That will be >much better to use then global system statistics about >MBR and SBR. Regards Wolfgang Breitling Centrex Consulting Corporation www.centrexcc.com -- //www.freelists.org/webpage/oracle-l