How to Keep All UNDO Segments from Being Offlined in Oracle 10g - Fast Ramp-Up
(Doc ID 396863.1)
Last updated on JANUARY 30, 2022
Applies to:Oracle Database Cloud Service - Version N/A and later
Oracle Database - Enterprise Edition - Version 10.2.0.1 to 10.2.0.5.0 [Release 10.2]
Oracle Database Cloud Schema Service - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
The purpose of this document is to explain how Oracle 10g uses Automatic Workload Repository (AWR) statistics to decide how many undo segments should be online when an instance is started.
Per the Oracle Database 10g New Features for Administrators Course, the concept of Fast Ramp-Up indicates the following:
"In previous versions, when the instance was restarted or when you switched undo tablespaces, the ramp-up time for the system to grow the number of online undo segments could be several minutes. Generally, this time delay was unacceptable.
After an instance startup or a switch of undo tablespaces in Oracle Database 10g, the database decides how many segments to place online, based on existing data stored in the the AWR."
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