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Guarantee Retention for Fixed Size Undo Tablespace [message #681740] Mon, 24 August 2020 08:04 Go to next message
Messages: 1
Registered: August 2020
Junior Member
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!
Re: Guarantee Retention for Fixed Size Undo Tablespace [message #681742 is a reply to message #681740] Mon, 24 August 2020 10:53 Go to previous message
John Watson
Messages: 8935
Registered: January 2010
Location: Global Village
Senior Member
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 Smile

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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