Last updated on APRIL 18, 2017
Applies to:Oracle Database - Standard Edition - Version 126.96.36.199 and later
Information in this document applies to any platform.
Plan regressions after upgrades is quite common. There are many reasons behind plan regressions, however it is a very broad subject to enumerate what has caused the plan regression in new upgraded environment. Sometimes the original plan from the preupgraded environment is desired even if the new plan produced in upgraded environment is better.
For such situations, Oracle has provided enough flexibility (outlines in old versions and SQL profiles/baselines in newer versions) in the hands of DBAs to quickly check and resolve such situations of getting the old plan back into the new upgraded environment, if it is still reproducible in the newly upgraded environment.
Implementing SQL profiles and baselines using COE profile scripts or DBMS packages can be handy. We use either COE scripts or DBMS packages to create SQL profile or baseline as needed to get that Old plan in new environment, provided customer has SQL Tuning and Diagnostics pack.
However in many cases, customers do not have SQL tuning and diagnostics pack, DBMS_SQLTUNE package cannot be used, as they are not licensed. In this case, stored outline can be used.
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