RE: Bind variable peeking and Dynamic sampling
- From: "Bobak, Mark" <Mark.Bobak@xxxxxxxxxxxxxxx>
- To: <Brandon.Allen@xxxxxxxxxxx>, <greg@xxxxxxxxxxxxxxxxxx>, "Oracle-L" <oracle-l@xxxxxxxxxxxxx>, <fairlie_r@xxxxxxxxx>
- Date: Tue, 8 May 2007 13:45:27 -0400
Brandon,
I agree that having a hint to selectively hard parse (or, really, just
selectively recompute execution plan) would be quite useful. But I
suspect Oracle is hesitant to provide it, for fear that it becomes a
"magic bullet", and people begin overusing it, causing an overall
degradation in performance. It would be great, but would need to be
very selectively applied.
-Mark
PS Hmm....now, where do I go to file an enhancement request?
--
Mark J. Bobak
Senior Oracle Architect
ProQuest/CSA
"There are 10 types of people in the world: Those who understand
binary, and those who don't."
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Allen, Brandon
Sent: Tuesday, May 08, 2007 12:58 PM
To: greg@xxxxxxxxxxxxxxxxxx; Oracle-L; fairlie_r@xxxxxxxxx
Subject: RE: Bind variable peeking and Dynamic sampling
Not that Wolfgang's suggestion isn't a good one, but just FYI - in my
case, I got rid of histograms and am still having the problems of
inappropriate plan sharing due to bind variable peeking.
I've filed enhancement request 6030306 to add a hint or some other
method of forcing Oracle to always hard-parse and bind-peek for certain
queries. If any of you agree this would be a good enhancement, please
submit an enhancement request of your own and reference the above ER
number and if enough of us ask for it, hopefully they'll add it soon.
Thanks,
Brandon
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Greg Rahn
Wolfgang's suggestion to remove any histograms might be the best bet.
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