Bingo. Looks like they formalized a paper in Jan, 2003. And Oracle is doing... what? ________________________________ From: Job Miller [mailto:jobmiller@xxxxxxxxx] Sent: Friday, June 09, 2006 12:42 PM To: Christian.Antognini@xxxxxxxxxxxx; Schultz, Charles Cc: oracle-l@xxxxxxxxxxxxx; Wolfgang Breitling Subject: RE: The CBO Lie Detector Isn't this what DB2 claims LEO already does? I had to take a class once taught by an ex-IBM Autonomic Computing guy who required I learn about LEO. "In this paper we introduce LEO, DB2's LEarning Optimizer, as a comprehensive way to repair incorrect statistics and cardinality estimates of a query execution plan. By monitoring previously executed queries, LEO compares the optimizer's estimates with actuals at each step in a QEP, and computes adjustments to cost estimates and statistics that may be used during future query optimizations. This analysis can be done either on-line or off-line on a separate system, and either incrementally or in batches. In this way, LEO introduces a feedback loop to query optimization that enhances the available information on the database where the most queries have occurred, allowing the optimizer to actually learn from its past mistakes." Job Miller oracle-l-bounce@xxxxxxxxxxxxx wrote: Charles >* I have to make a small disclaimer that I have not fully read the >paper, yet. I have only found an abstract, and am still looking for the >full thing. I did not find it on the OakTable.net or hotsos, but am >going through the rest of my google hits. You find Wolfgang's paper on his homepage (www.centrexcc.com). HTH Chris -- //www.freelists.org/webpage/oracle-l __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com