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Question and Answer

Connor McDonald

Thanks for the question, krishna.

Asked: March 20, 2017 - 9:17 am UTC

Last updated: March 23, 2017 - 3:18 am UTC

Version: 11.2.0.4

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You Asked

Hi ,

Why we need separate undo and temp table space in rac and please justify

and Connor said...

Because we do...

...and also it makes a lot of sense to do so.

If we had to compete for a shared undo and shared temp, then this means more coordination between instances, more cross-instance traffic, more contention.

Instance-local structures improve performance.


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elaborate please

A reader, March 22, 2017 - 9:39 am UTC

hello

1) what the terme "rac" make difference in the answer?? this still valid for non rac db? or not same answer fits?

2) "Instance-local structures improve performance."
what do you mean exactly ? could pls elaborate with 1 or 2 use cases?
Connor McDonald
March 23, 2017 - 3:18 am UTC

1) non-rac doesnt apply here, because its all on one box.

2) If I had (say) a single undo structure, then all instances would have to compete for resources within it. Competition (generally) = contention, because you need structures to guarantee you dont clash with others.

By each instance having its own undo, they dont interfere with each other for resources.
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