| Guarantee Retention for Fixed Size Undo Tablespace [message #681740] |
Mon, 24 August 2020 08:04  |
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adojuki
Messages: 1
Registered: August 2020
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Junior Member |
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Hi there OracleFAQ Community!
I am currently studying for my OCA certification exam and was wondering about the use of a fixed size undo tablespace with guarantee retention enabled.
Oracle, as far a I know, ignores any undo retention for fixed size undo tablespaces, and may re-use unexpired undo to support new transactions if necessary.
So I was wondering what is the behaviour if you have a fixed size undo tablespace with guarantee retention enabled? Is the undo retention still ignored or does the guarantee retention take precedence over it?
I am not completely sure but my guess would be that the undo retention is still ignored.
My colleague took the exam a few months prior and told me the that he can remember a question like this (but he isn't sure about the right answer), so I was wondering what you people think about this.
Best regards!
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| Re: Guarantee Retention for Fixed Size Undo Tablespace [message #681742 is a reply to message #681740] |
Mon, 24 August 2020 10:53  |
John Watson
Messages: 8962
Registered: January 2010
Location: Global Village
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Senior Member |
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Welcome to the forum. Please read the OraFAQ Forum Guide and How to use code tags and make your code easier to read
What you need to do is test: create a small undo tablespace, set retention guarantee and a long retention time, then do a lot of DML. You will see what happens when the undo tablespace fills up with unexpired undo. If you can make a nice repeatable test case, post it here as a blog article and be famous 
As a hint: consider the options. Either Oracle will have to break the guarantee, or it will have to block DML until the retention time is passed. Which do you think is a better solution, given that Oracle always strives for zero data loss?
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