Hi,
Another issue for a 10g->11g upgrade would be the optimizer cardinality
feedback and (to a lesser degree for us) , the adaptive cursor sharing
features, which are both enabled by default (although I don't remember now if
optimizer_features_enabled=10.2.0.4 effectively disables the cardinality
feedback)
Of the above, the cardinality feedback was really a major pain for us (for a 9i
-> 11g ugrade). Many optimizer plans regressed (the application didn't
properly used bind variables, and the supposedly "intelligent" cardinality
feedback algorithm choosed bad plans for the most important queries). It also
depends on the level of patching of the 11203 release (until a certain level of
patches there were many optimizer bungs related to the two areas above)
You could try disabling the cardinality feedback at least temporarily, via an
"alter session (or system) set _optimizer_use_feedback=false", flush the
shared pool (or if possible for you, rebounce the instance) , and then check to
see the generated plans.
regards,
alvaro
________________________________
De: oracle-l-bounce@xxxxxxxxxxxxx [oracle-l-bounce@xxxxxxxxxxxxx] en nombre de
Mandal, Ashoke [ashoke.k.mandal@xxxxxxxxxxxxx]
Enviado: lunes, 19 de octubre de 2015 21:48
Para: fuzzy.graybeard@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Asunto: RE: Database perfortmance degraded drastically after upgrading the
database from Oracle 102.0.4 to Oracle 11.2.0.3
It is on Solrais 10.
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Hans Forbrich
Sent: Monday, October 19, 2015 2:41 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: Database perfortmance degraded drastically after upgrading the
database from Oracle 102.0.4 to Oracle 11.2.0.3
Which platform, which features and options do you have?
I would recommend using Diag Pack and AWR reports, but if you don't have EE and
OEM and DiagPack, it would be a wast of time recommending them.
/Hans
On 19/10/2015 1:21 PM, Mandal, Ashoke wrote:
Greetings All,
After the upgrade of one of my databases from Oracle 10.2.0.4 to Oracle
11.2.0.3 the users are experiencing poor query performance. The response time
of the queries have increased by 15 times.
I have tried the following without any luck but checking if you have any other
suggestions
1. Changed optimizer_dynamic_sampling from 2 to 1 => No performance
improvement
2. Changed optimizer_features_enable to '10.2.0.4' => No performance
improvement
3. Try setting cursor_sharing to force => No performance improvement
4. Set “_optimizer_skip_scan_enabled" = FALSE => No performance improvement
Please let me know if you any suggestions to resolve this issue
Appreciate your help in advance,
Ashoke
[CONFIDENTIALITY AND PRIVACY NOTICE] Information transmitted by this email is
proprietary to Medtronic and is intended for use only by the individual or
entity to which it is addressed, and may contain information that is private,
privileged, confidential or exempt from disclosure under applicable law. If you
are not the intended recipient or it appears that this mail has been forwarded
to you without proper authority, you are notified that any use or dissemination
of this information in any manner is strictly prohibited. In such cases, please
delete this mail from your records. To view this notice in other languages you
can either select the following link or manually copy and paste the link into
the address bar of a web browser:
http://emaildisclaimer.medtronic.com<http://emaildisclaimer.medtronic.com/>
