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Tuning Oracle UNDO segments
Oracle Tips by Burleson Consulting |
Question:
I have seen a lot of redo log contention of private strand
flushes related to in memory undo, but I have not been able to
find any comprehensive information about in memory undo or how
to tune it. How do you tune your UNDO for optimal performance?
Answer:
The UNDO segments are used for read consistency, flashback
database and for transaction recovery and you have a number of
tuning knobs. I have complete details in my book
"Oracle
Tuning: The Definitive Reference". Also see the 10g UNDO advisor
utility for advice on the optimal UNDO configuration.
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Settings - Parameters such as transactions_per_rollback_segment and
the size of the UNDO tablespace.
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Faster storage - Using solid-state disk
is a great way to speed up UNDO writing as it can be up to 300x faster than
platter disk UNDO.
Also see my notes relating to UNDO
tuning:
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If you like Oracle tuning, see the book "Oracle
Tuning: The Definitive Reference", with 950 pages of tuning tips and
scripts.
You can buy it direct from the publisher for 30%-off and get
instant access to the code depot of Oracle tuning scripts. |
