Automatic Undo Internals by Daniel Fink
Automatic Undo Management (AUM), also referred to as System Managed Undo (SMU), was introduced in Oracle9i in response to performance and administrative difficulties associated with rollback segments. AUM is widely publicized in marketing materials. However, there is little actual documentation on the mechanics and management of automatic undo from a DBA's perspective. This paper will shed light on the actual operations of automatic undo management. One important concept to keep in mind is that much of what we will review is related to undoing actions. As such, there is a great deal of 'reverse' terminology and presentation. For example, undo is read in reverse order, from the last entry to the first. Instead of reading the next entry, we read the previous. .sense makes that hope I
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- Author:: Daniel Fink
- Item #: Paper0017
