7 Downgrading a Database

Supported Releases for Downgrading

You can downgrade both major releases and patchset releases, based on the original version from which the database was upgraded. Major release downgrades are supported back to 10.2 and 10.1. Patchset downgrades are supported back to all prior 11.1 patch releases.

In all discussions of downgrading, it is important to understand that you can only downgrade to the release from which you upgraded. For example, if you upgraded from Oracle Database 10g Release 1 (10.1) to Oracle Database 11g Release 1 (11.1), then you could not subsequently downgrade to Oracle Database 10g Release 2 (10.2); you could only downgrade to Oracle Database 10g Release 1 (10.1).

If the release number of your Oracle 10g Release 1 (10.1) database is lower than 10.1.0.5, then you should install the latest patch for Oracle Database 10g Release 1 (10.1) prior to downgrading. Similarly, if the release number of your Oracle 10g Release 2 (10.2) database is lower than 10.2.0.3, then you should install the latest patch release for 10.2 prior to downgrading. Note that you can upgrade from any patch release of 10.1 or 10.2, but you should install the latest patch release in the Oracle home you intend to use after downgrading.

If you have Database Vault installed with your Oracle 11g Release 1 database, you can downgrade to release 10.2.0.4 only. Downgrade to 10.2.0.3 is not supported with Database Vault.

If you have Messaging Gateway or Workspace Manager in your database, then be aware that neither of them are part of Oracle Database patchsets prior to release 10.2.0.4. Therefore, you must separately apply all relevant patches to the release 10.2.0.3 or release 10.1.0.5 Oracle home before downgrading.

Downgrade is not supported for Oracle Enterprise Manager. But if you save your Oracle Enterprise Manager Database Control files and data before upgrading your database, then you can restore the old version of Database Control after downgrading the database.

In any event, if you have Enterprise Manager configured in your database, then you must drop the SYSMAN schema before downgrading the database. Run the following command to drop the SYSMAN schema:

DROP USER sysman CASCADE

Check for Incompatibilities

Check the compatibility level of your database to see if your database might have incompatibilities that prevent you from downgrading. If the compatibility level of your Oracle Database 11g Release 1 (11.1) database is 11.0.0 or higher, then you are not able to downgrade. Your compatibility level is determined by the setting of the COMPATIBLE initialization parameter. Check your COMPATIBLE initialization parameter setting by issuing the following SQL statement:

SQL> SELECT name, value, description FROM v$parameter
         WHERE name='compatible';

If you are downgrading to Oracle Database 10g Release 2 (10.2), then the COMPATIBLE initialization parameter must be set to 10.2.0 or lower.

If you are downgrading to Oracle Database 10g Release 1 (10.1), then the COMPATIBLE initialization parameter must be set to 10.1.0.

Perform a Full Backup

Perform a full backup of your Oracle Database 11g Release 1 (11.1) database before you downgrade.

Downgrade the Database

Complete the following steps to downgrade your Oracle Database 11g Release 1 (11.1) database to a major release or a relevant patchset upgrade:

1. If you have enabled Oracle Database Vault on your database, then you must disable it before downgrading the database.

   See Also:

   Oracle Database Vault Administrator's Guide for instructions on disabling Oracle Database Vault

2. Log in to the system as the owner of the Oracle Database 11g Release 1 (11.1) Oracle home directory.

   Note: This step is required only if Enterprise Manager Database Control is already configured for the database.

   Stop the Database Control, as follows:

   1. Set the ORACLE_SID environment variable to the databaseSid

   2. Run the following command:

      ORACLE_HOME/bin/emctl stop dbconsole
      
      

   If the database being downgraded is an Oracle Real Application Clusters (Oracle RAC) database, then this step should be performed for all the instances.

3. If you are downgrading an Oracle RAC database to 10g Release 1 (10.1), then you must remove extra voting disks before shutting down the Oracle Clusterware stack.

   1. To see the number of voting disks used and to list voting disk paths, run the following command:

      Oracle_Clusterware_Home/bin/crsctl query css votedisk
      
      

   2. Remove each additional voting disk you find in the previous step by running the following command, where path is a voting disk path discovered in the previous step:

      Oracle_Clusterware_Home/bin/crsctl delete css votedisk path
      
      

4. At a system prompt, change to the ORACLE_HOME/rdbms/admin directory.

   Note:

   If you are downgrading a cluster database, then shut down the instance completely and change the CLUSTER_DATABASE parameter to false. After the downgrade, you must set this parameter back to true.

5. Start SQL*Plus.

6. Connect to the database instance as a user with SYSDBA privileges.

7. Start up the instance in DOWNGRADE mode:

   SQL> STARTUP DOWNGRADE
   
   

   You might be required to use the PFILE option to specify the location of your initialization parameter file.

8. Drop the SYSMAN schema:

   DROP USER sysman CASCADE;
   
   

9. Set the system to spool results to a log file for later verification of success:

   SQL> SPOOL downgrade.log
   
   

10. Run catdwgrd.sql:

    SQL> @catdwgrd.sql
    
    

    The following are notes about running the script:

    • You must use the version of the script included with Oracle Database 11g Release 1 (11.1).

    • You must run the script in the Oracle Database 11g Release 1 (11.1) environment.

    • The script downgrades all Oracle Database components in the database to the major release or 11g patch release from which you originally upgraded.

    If you encounter any problems when you run the script, or any of the scripts in the remaining steps, then correct the causes of the problems and rerun the script. You can rerun any of the scripts described in this chapter as many times as necessary.

    If the downgrade for a component fails, then an ORA-39709 error is displayed and the SQL*Plus session terminates without downgrading the Oracle Database data dictionary. All components must be successfully downgraded before the Oracle Database data dictionary is downgraded. You must identify and fix the problem before rerunning the catdwgrd.sql script.

11. Turn off the spooling of script results to the log file:

    SQL> SPOOL OFF
    
    

    Then, check the spool file and verify that there were no errors generated during the downgrade. You named the spool file in Step 9; the suggested name was downgrade.log. Correct any problems you find in this file and rerun the downgrade script if necessary.

12. Shut down the instance:

    SQL> SHUTDOWN IMMEDIATE
    
    

13. Exit SQL*Plus.

14. If your operating system is Linux or UNIX, then change the following environment variables to point to the directories of the release to which you are downgrading:

    • ORACLE_HOME

    • PATH

    You should also check that your oratab file and any client scripts that set the value of ORACLE_HOME point to the downgraded Oracle home.

    See Also:

    Your operating system-specific Oracle Database 11g Release 1 (11.1) installation documents for information about setting other important environment variables on your operating system

15. If your operating system is Windows, then complete the following steps:

    1. Stop all Oracle services, including the OracleServiceSID Oracle service of the Oracle Database 11g Release 1 (11.1) database, where SID is the instance name.

       For example, if your SID is ORCL, then enter the following at a command prompt:

       C:\> NET STOP OracleServiceORCL
       
       

       See Also:

       The Oracle Database Platform Guide for Microsoft Windows that is specific to your Microsoft Windows environment for information about stopping services

    2. Delete the Oracle service at a command prompt by issuing the ORADIM command. For example, if your SID is ORCL, then enter the following command:

       C:\> ORADIM -DELETE -SID ORCL
       
       

    3. Create the Oracle service of the database that you are downgrading at a command prompt using the ORADIM command.

       C:\> ORADIM -NEW -SID SID -INTPWD PASSWORD -MAXUSERS USERS
            -STARTMODE AUTO -PFILE ORACLE_HOME\DATABASE\INITSID.ORA
       
       

       This syntax includes the following variables:

       Variable	Description
       SID	Same SID name as the SID of the database being downgraded.
       PASSWORD	Password for the database instance. This is the password for the user connected with SYSDBA privileges. The -INTPWD option is not required. If you do not specify it, then operating system authentication is used, and no password is required.
       USERS	Maximum number of users who can be granted SYSDBA and SYSOPER privileges.
       ORACLE_HOME	Oracle home directory of the database to which you are downgrading. Ensure that you specify the full path name with the -PFILE option, including drive letter of the Oracle home directory.

       
       

       For example, if you are downgrading to Oracle Database 10g Release 2 (10.2), if your SID is ORCL, your PASSWORD is TWxy5791, the maximum number of USERS is 10, and the ORACLE_HOME directory is C:\ORANT, then enter the following command:

       C:\> ORADIM -NEW -SID ORCL -INTPWD TWxy5791 -MAXUSERS 10
            -STARTMODE AUTO -PFILE C:\ORANT\DATABASE\INITORCL.ORA
       

       Note:

       You are not required to change any Windows Registry settings when downgrading a database. The oradim utility makes all necessary changes automatically.

16. Restore the configuration files (for example, parameter files, password files, and so on) of the release to which you are downgrading.

    If this is an Oracle RAC database, execute the following command to return the database to single instance mode:

    SET CLUSTER_DATABASE=FALSE
    

    Note:

    If you are downgrading a cluster database, then perform this step on all nodes in which this cluster database has instances configured.

    • Set the CLUSTER_DATABASE initialization parameter to false. After the downgrade, you must set this initialization parameter back to TRUE.

17. At a system prompt, change to the ORACLE_HOME/rdbms/admin directory of the previous release.

18. Start SQL*Plus.

19. Connect to the database instance as a user with SYSDBA privileges.

20. Start up the instance:

    SQL> STARTUP UPGRADE
    
    

21. Set the system to spool results to a log file for later verification of success:

    SQL> SPOOL reload.log
    
    

22. Run catrelod.sql:

    SQL> @catrelod.sql
    
    

    The catrelod.sql script reloads the appropriate version of all of the database components in the downgraded database.

23. If you are downgrading to release 10.1.0.5 and you have XDB in your database, run the following script after running catrelod.sql:

    @dbmsxdbt.sql
    
    

24. Turn off the spooling of script results to the log file:

    SQL> SPOOL OFF
    
    

    Then, check the spool file and verify that the packages and procedures compiled successfully. You named the spool file in Step 21; the suggested name was reload.log. Correct any problems you find in this file and rerun the appropriate script if necessary.

25. Shut down and restart the instance for normal operation:

    SQL> SHUTDOWN IMMEDIATE
    SQL> STARTUP
    
    

    You might be required to use the PFILE option to specify the location of your initialization parameter file.

26. Perform this step if the database is configured for Oracle Label Security and you are downgrading from Oracle Database 10g Release 1 (10.1) or Oracle Database 10g Release 2 (10.2). Copy the olstrig.sql script from the Oracle Database 11g Release 1 (11.1) Oracle home to the Oracle home of the version to which the database is to be downgraded. Run olstrig.sql to re-create DML triggers on tables with Oracle Label Security policies. (See Oracle Database Enterprise User Security Administrator's Guide for more information.)

    SQL> @olstrig.sql
    
    

27. Run the utlrp.sql script:

    SQL> @utlrp.sql
    
    

    The utlrp.sql script recompiles all existing PL/SQL modules that were previously in an INVALID state, such as packages, procedures, types, and so on.

28. Exit SQL*Plus.

Your database is now downgraded.

Perform Post-Downgrade Tasks

This section discusses tasks that might be required after downgrading a database.

This section contains the following topics:

• Downgrading Oracle Clusterware Configuration

• Restoring Oracle Enterprise Manager

  • Single-Instance Oracle Database Without ASM

  • Oracle RAC Database Without ASM

  • Single-Instance Oracle ASM Instance

  • Oracle RAC ASM Instance

  • Single-Instance Oracle Database With ASM

  • Oracle RAC Database and ASM Instance

• Enabling Oracle Database Vault

111Home/bin/emca -restore db

111Home/bin/emca -restore db -cluster

111Home/bin/emca -restore asm

111Home/bin/emca -restore asm -cluster

111Home/bin/emca -restore db_asm

111Home/bin/emca -restore db_asm -cluster

> emca -restore db
 
STARTED EMCA at Mar 23, 2007 2:44:17 PM
EM Configuration Assistant, Version 11.1.0.3.0 Production
Copyright (c) 2003, 2005, Oracle.  All rights reserved.
Enter the following information:
Mar 23, 2007 2:44:17 PM oracle.sysman.emcp.util.GeneralUtil initSQLEngine
SEVERE: No SID specified
ORACLE_HOME for the database to be restored: /scratch/oracle/10.2.0/product/db_1
Database SID: DB102
Listener port number: 1521
Password for SYS user:  oracle
Do you wish to continue? [yes(Y)/no(N)]: Y
Mar 23, 2007 2:47:29 PM oracle.sysman.emcp.EMConfig perform
INFO: This operation is being logged at /scratch/oracle/cfgtoollogs/emca/DB102/emca_2007_03_23_14_44_17.log.
Mar 23, 2007 2:47:30 PM oracle.sysman.emcp.util.DBControlUtil stopOMS
INFO: Stopping Database Control (this may take a while) ...
Mar 23, 2007 2:47:41 PM oracle.sysman.emcp.util.DBControlUtil startOMS
INFO: Starting Database Control (this may take a while) ...
Mar 23, 2007 2:48:06 PM oracle.sysman.emcp.EMDBPostConfig performRestore
INFO: Database Control started successfully
Mar 23, 2007 2:48:06 PM oracle.sysman.emcp.EMDBPostConfig performRestore
INFO: >>>> The Database Control URL is http://stadd17.us.oracle.com:1158/em <<<<<<
Enterprise Manager configuration completed successfully
FINISHED EMCA at Mar 23, 2007 2:48:06 PM