Last updated on OCTOBER 06, 2017
Applies to:Oracle Database - Standard Edition - Version 10.1.0.5 to 22.214.171.124 [Release 10.1 to 11.2]
Oracle Database - Enterprise Edition - Version 10.1.0.5 to 126.96.36.199 [Release 10.1 to 11.2]
Information in this document applies to any platform.
This document is created for use as a guideline and checklist for downgrading a previously upgraded database from Oracle 11gR2 back to the previous release: Oracle 10gR1, Oracle 10gR2, Oracle 11gR1. It is also useful for downgrading from 188.8.131.52 to 184.108.40.206
Additional, corrective actions (such as de-install / re-install or re-upgrade to current patchset levels) may be needed to settle left-over issues after a downgrade.
If the goal is to have the instance back EXACTLY as it was pre-upgrade then other processes including a recovery to just before the upgrade should be used.
The process discussed in this article is a script based downgrade. This article does not discuss the use of Export / Import, Data Pump or other methods to move data from one version to another.
Oracle binaries of the release/version to which you are downgrading should be available/installed on the server before you start the downgrade process. If you have uninstalled the Oracle executable's to which you want to downgrade, please re-install the oracle binaries to the correct version / patch level for the downgrade.
Please note the following:
- This process is only valid for databases upgraded using either the DBUA or manual upgrade process. Databases that are moved from one version to another using process (like Export / Import, Data Pump, TTS, ... etc) cannot use this process.
- This process is intended to downgrade a database that was successfully upgraded to 11gR2. It is not intended to back out from a failed upgrade.
- You can only downgrade to the release and patch level you upgraded from. For example, if you upgraded from Oracle 10gR1 (10.1.0.5) to Oracle 11gR2 (11.2), then you can not downgrade to Oracle 10gR2 (10.2). You can only downgrade to Oracle 10gR1 (10.1.0.5)
- Downgrades to 9iR2 are not supported. This is because in the upgrade process the compatible parameter is set to a minimum 10.1.0. This prevents downgrades. See <Note 388604.1> : ORA-00201 while downgrading from 10gR2 to 10gR1 or 9iR2 for additional information.
- If there are any patches applied on the source database running from the upgraded home, they need to be rolled back before beginning the downgrade process. The steps to un-install and roll back patches are documented in the readme for the patch in question. Failure to un-install and roll back patches can result in a failure to downgrade including dictionary objects that cannot be re-validated.
Example: For an Exadata Bundle Patch, the procedure is to:
Un-install the patch
Example: $ opatch auto /u01/app/oracle/patches/14103267 -rollback
Roll back any SQL applied as part of the patch application:
Example: SQL> @rdbms/admin/catbundle_EXA_<database SID>_ROLLBACK.sql to rollback SQL changes.
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