In the following blog article in response to my comment Jonathan Lewis wrote this *"Although optimizer_features_enable will make the optimizer revert to earlier behaviour, I don’t think there’s any guarantee that it will re-introduce bugs that were present in earlier versions"* http://jonathanlewis.wordpress.com/2011/03/02/first_rows/#comments Best regards Mohamed Houri 2014-11-27 13:13 GMT+01:00 Mauro Pagano <mauro.pagano@xxxxxxxxx>: > I don't have any example handy but any CBO fix that is not under a > fix_contol (ie. fix for wrong result bugs or ora-600/7445) would not be > disabled by an older OFE and so if such fix is responsible for a plan > change then changing OFE param will not revert to the old plan > > Sent from my iPhone > > On Nov 27, 2014, at 3:32 AM, Chitale, Hemant K <Hemant-K.Chitale@xxxxxx> > wrote: > > I am looking for notes and/or examples that show that, after an upgrade > and execution plan changes, even resetting OFE doesn’t always help. That > is : OFE set to the previous version doesn’t guarantee that execution > plan and runtime will be exactly as it was in the earlier version. > > One example I find is at > *http://jonathanlewis.wordpress.com/2014/11/03/upgrades-4/* > <http://jonathanlewis.wordpress.com/2014/11/03/upgrades-4/> > > Any more would help me. > > Hemant K Chitale > > > This email and any attachments are confidential and may also be > privileged. If you are not the intended recipient, please delete all copies > and notify the sender immediately. You may wish to refer to the > incorporation details of Standard Chartered PLC, Standard Chartered Bank > and their subsidiaries at https://www.sc.com/en/incorporation-details.html > . > > -- Houri Mohamed Oracle DBA-Developer-Performance & Tuning Member of Oraworld-team <http://www.oraworld-team.com/> Visit My - Blog <http://www.hourim.wordpress.com/> Let's Connect - <http://fr.linkedin.com/pub/mohamed-houri/11/329/857/>*Linkedin Profile <http://fr.linkedin.com/pub/mohamed-houri/11/329/857/>* My Twitter <https://twitter.com/MohamedHouri> - MohamedHouri <https://twitter.com/MohamedHouri>