RE: Monitoring CBO degrading Switches in xplans?
Date: Tue, 23 Jun 2009 14:49:23 -0400
Oracle recommended it, but with the disclaimer that you do your own testing. The test setup is currently in progress. I would like to hear from DBA'S who actually implemented it and how did it impact performance?
From: Andrew Kerber <andrew.kerber_at_gmail.com> Sent: Thursday, June 18, 2009 6:04 PM
Cc: Oracle-L Group <oracle-l_at_freelists.org> Subject: Re: Monitoring CBO degrading Switches in xplans?
Did you try turning off bind variable peeking or histograms?
On Thu, Jun 18, 2009 at 4:51 PM, Fmhabash <fmhabash_at_gmail.com> wrote:
> This is an issue that has made sleepless over and over again. Critical
> application sql changes its xplans causing elapse time to go unacceptably
> We eventually wanted to monitor this kind of event proactively. To this
> effect, we query top n sql from awr order by elapsed time. We then compare
> most recent ET value to the previous n samples. We then calculate cost of
> current plan and compare it to existing awr ones cost.
> With all this info, we alert if ET and plan cost exceed thresholds.
> How do you cope with this issue and what have you done to monitor it (logic
> Thank You.
-- Andrew W. Kerber 'If at first you dont succeed, dont take up skydiving.' -- http://www.freelists.org/webpage/oracle-lReceived on Tue Jun 23 2009 - 13:49:23 CDT