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Very high "TUNED_UNDORETENTION" => It's equal to instance runtime

edited Aug 27, 2020 3:58AM in Database Administration (MOSC) 42 commentsAnswered ✓

Hi,

Oracle 12.2.0.1 (RAC and Multitenant) env OL 7.5

I investigate a little bit an issue, that "UNEXPIRED" blocks in undo tablespace never become expired as long as the undo datafile is full or the undo datafile is full and no more autoextensible yet (then it is first autextended up to it's limit).

I have tested this several times.

The SR I've opened says this is expected behaivior. But I'm not sure and it's not plausible for me.

The "TUNED_UNDORETENTION" is continuously increasing and reflects exactly the runtime of the instance. There is no active transaction. I suppose the "TUNED_UNDORETENTION" is responsible for expiring undo blocks. Hence unexpired blocks were never expired, if "TUNED_UNDORETENTION" is only increasing.

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