You can reach the Rollback Segment Manager via the Enterprise Manager and the Storage node. Double clicking the Rollback Segments node will open a window similar to the one below.
Note:
If your Oracle server does not use Rollback Segments, the Rollback Segments node will not be visible.
The Oracle Rollback Segment Manager
The list displays the currently available rollback segments, their status and current size. From here, you can create new, edit or drop rollback segments. In addition to that, you can take rollback segments OFFLINE and bring them ONLINE.
When editing or creating a new rollback segment, use the OK button to save your changes and the Cancel button to cancel your changes.
Note:
The user you used to register the server needs to have access to views DBA_ROLLBACK_SEGS, DBA_SEGMENTS and V$ROLLSTAT for this feature to work.
Creating a New Rollback Segment
Use the New Rollback Segment to start the dialog as shown below:
The Rollback Segment dialog
Here you can specify the Rollback Segment attributes.
By using the "[default]" for the extent attributes, you're using the database defaults.
Editing a Rollback Segment
Double clicking a rollback segment will show the Edit Rollback Segment dialog, similar to the one above.
Some options might be read only, like the name and tablespace.
Using the Online checkbox you can take the rolback segment offline or bring it online, see below.
Dropping a Rollback Segment
You can only drop a rollback segment with a status of OFFLINE. When using the Drop Rollback Segment button, you will be asked to confirm and if you choose Yes, the rollback segment will be dropped.
Take a Rollback Segment Offline
If you take a rollback segment offline, it will no longer be used by Oracle to hold data needed to rollback DML statements. Once taken offline, you can drop the rollback segment.
You can take a rollback segment offline by selecting an active rollback segment and using the Take Offline button.
Take Offline button
After the confirmation, Database Workbench will attempt to take the rollback segment offline. In case of errors, you will get a message and the rollback segment will stay online. If the status changes, the image for the rollback segment will change to a "grayed" image.
Bring a Rollback Segment Online
You can bring a rollback segment back online so that it's available for use by using the Bring Online button.
Bring Online button
After bringing a rollback segment online, the image of the rollback segment will change to an active one.