Resolving ORA-00392 During ALTER DATABASE OPEN RESETLOGS

Scenario

While attempting to open an Oracle database after recovery using:

SQL> alter database open resetlogs;
alter database open resetlogs
*

ERROR at line 1:
ORA-00392: log 4 of thread 1 is being cleared, operation not allowed
ORA-00312: online log 4 thread 1:
'/oradata/datafile/fahdb/onlinelog/group_4.268.792016823'
ORA-00312: online log 4 thread 1:
'/oradata/datafile/fahdb/onlinelog/group_4.257.792016845'

Understanding the Issue

This error typically indicates that an online redo log file is invalid or partially cleared. Oracle cannot proceed with OPEN RESETLOGS because the log is unarchived and may contain incomplete or uncommitted transactions.

Resolution

To resolve this, we can safely clear the problematic log group—provided we are sure it's no longer needed for recovery. In my case, this was log group 4.

Step 1: Clear the Unarchived Log Group

SQL> alter database clear unarchived logfile group 4;

Database altered.

Step 2: Retry Opening the Database

Now that the corrupted/unusable log group has been cleared, retry opening the database:

SQL> alter database open resetlogs;

Step 3: Verify Database Status

SQL> select open_mode from v$database;

OPEN_MODE

--------------------

READ WRITE

SQL>

Important Considerations

Clearing logs is irreversible. Ensure all necessary recovery steps are complete and that the redo log group in question is not needed for point-in-time recovery.

Always have a valid backup before performing any operations involving redo log manipulation.

This is typically part of a manual recovery or restore process, especially when dealing with incomplete recovery scenarios.

Conclusion

Encountering ORA-00392 can be alarming, especially after a restore operation. However, understanding the purpose of redo logs and how to safely handle unarchived ones is critical. With the right approach, we can bring the database back online confidently and securely.