Thank you all for your help, we will be cloning prod down this weekend so I am curious to see if the same plan is generated or if it will mirror prod and dev. I am still analyzing the trace files but the cause doesn't pop out at me. Ken Naim _____ From: Wolfgang Breitling [mailto:breitliw@xxxxxxxxxxxxx] Sent: Friday, January 13, 2006 6:44 AM To: niall.litchfield@xxxxxxxxx Cc: Mladen Gogala; kennaim@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx Subject: Re: Poorly performing query and 10053 trace To be correct, my article describes the CBO 8.1 trace and, to some degree behaviour. Jonathan's book not only describes a far more recent 10.1 10053 trace in chapter 14, the preceding chapters go far beyond what my paper did. In comparison to the book, the best that can be said about my paper is that it's free - and you know the adage "you get what you pay for". Of course, that is not always correct. With Jonathan's book you get much more than you pay for. For the record, I do not get any royalties for increased sales. I just think it is an exceptional book and my little blurb pales in comparison besides becoming incredibly dated. At 02:37 AM 1/13/2006, Niall Litchfield wrote: On 1/13/06, Mladen Gogala <gogala@xxxxxxxxxxxxx > wrote: Not wanting to diminish Jonathan's exquisite book, there is also an excellent article by Mr. Wolfgang Breitling, on http://www.centrexcc.com. The description is excellent and immediately usable. I can't believe I forgot that one. Regards Wolfgang Breitling Centrex Consulting Corporation www.centrexcc.com