Automated UNDO Management

Automated Undo Management (AUM)

9i’s new feature Automated Undo Management (AUM) relieves you of the traditional, labor-intensive task of sizing and managing rollbacks. To use AUM, create a tablespace that will be used for rollbacks (the UNDO tablespace). Then start the instance with these two new 9i initialization parameters set to:

UNDO_MANAGEMENT = AUTO

UNDO_TABLESPACE = undo_tablespace_name

Once an instance is started with AUM, you can not and do not create or manage rollback segments manually. You can switch to another UNDO tablespace whenever you want, but you can not drop an UNDO tablespace while it has active transactions.