426 Part III ✦ Administering Storage for Oracle Objects
4. Why do you need multiple rollback segments?
5. What is the difference between an online and offline rollback segment? 6. What is the significance of the OPTIMAL parameter?
Chapter 10 ✦ Managing Rollback Segments
Once you have a sound understanding of their use, managing rollback segments is really not that difficult. You must make sure that there are enough of them to prevent contention and make sure they are appropriately sized to avoid dynamic extension or, what is worse, running out of space. If a transaction runs out of rollback space, it rolls back. If it took two hours to run out of space, it will probably take another two hours to rollback. Now four hours have elapsed and the
transaction is right back where it started.
The Use of Rollback Segments