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What is actually undo_retention [message #267981]

Mon, 17 September 2007 01:15

sureshkay
Messages: 21
Registered: June 2007

Junior Member

Does the undo_retention means the life time of the uncommited data OR Commited Data

which one of the below statement corretly defines the Definition of undo_Retention:

1. If I commit the Transaction the undo segment will remain active till the undo_retention time is over and then it overwrites the segment

2. If there are uncommited Transactions then undo_retention defines the life time for the undo segment and when the time expires the undo segment expires.

One more question:
from Oracle Documentation:
However, since DROP TABLESPACE drops an undo tablespace even if it contains unexpired undo information (within retention period), you must be careful not to drop an undo tablespace if undo information is needed by some existing queries.

How is it possible to drop undo tablespace when the there are unexpired undo information ???
can any one explain with a example.

[Updated on: Mon, 17 September 2007 01:28]

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Re: What is actually undo_retention [message #267987 is a reply to message #267981]

Mon, 17 September 2007 01:36

Arju
Messages: 1554
Registered: June 2007
Location: Dhaka,Bangladesh. Mobile:...

Senior Member

http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/undo.htm#BJFEHEIC

This is Undo Retention.

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Re: What is actually undo_retention [message #267989 is a reply to message #267987]

Mon, 17 September 2007 01:45

sureshkay
Messages: 21
Registered: June 2007

Junior Member

Yes it is clear and it also answers my question from new topic i submitted "Undo Tablespace takes time to switch from pending offline to offline mode". Thanks

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