How to restore oracle upgrade failed

Oracle Restore Method after Failed Upgrade

Oracle upgrades can sometimes fail, causing the system to be unavailable. To restore the system, perform the following steps:

1. Terminate recovery

• Stop the database instance.
• Switch to recovery mode: sqlplus / as sysdba .
• Run the following command: STARTUP NOMOUNT;

2. Roll back the data file

• Use the recovery command to roll back the data file:

   <code>RECOVER DATABASE UNTIL CANCEL USING BACKUP CONTROLFILE TO '\\path\\to\\controlfile_backup';</code>

3. Open the database

• Run the following command to reopen the database: STARTUP mount;
• Confirm that all data files are installed: SELECT NAME FROM V$DATAFILE;
• Recover redo logs: ALTER DATABASE OPEN RESETLOGS;

4. Recreate the control file

• If the control file is corrupted, recreate it:

   <code>CREATE CONTROLFILE REUSE DATABASE '<database_name>' AS '<path>';</path></database_name></code>

5. Reopen the database

• Reopen the database in full recovery mode: ALTER DATABASE OPEN;

6. Verify restore

• Run the integrity check on the database: SELECT * FROM SYS.DBA_CONSISTENCY;
• Confirm that all data and objects are intact.

7. Roll back the rollback segment

• If a rollback segment is created during the restore process, roll it back: ROLLBACK SYSTEM TO SCN <scn before upgrade>;</scn>

hint:

• Be sure to back up the database before performing any restore operations.
• If you cannot resolve the restore problem yourself, seek Oracle support.

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