Home » RDBMS Server » Server Administration » UNDO MANAGEMENT (Oracle Standard 11.2.0.3 , OEL 6.4)
icon5.gif  UNDO MANAGEMENT [message #613071] Tue, 29 April 2014 07:12 Go to next message
silas.silva@gmail.com
Messages: 2
Registered: April 2014
Junior Member
Why is there a difference between these two procedures? how to estimate the size of the undo tablespace?

These are my results

Procedure 1 -

select dbms_undo_adv.longest_query(sysdate-10, sysdate) from dual;

1798

select dbms_undo_adv.required_undo_size (1798, sysdate-10, sysdate) from dual;

1385

Procedure 2 -

select DBMS_UNDO_ADV.RBU_MIGRATION from dual;

19576
Re: UNDO MANAGEMENT [message #613073 is a reply to message #613071] Tue, 29 April 2014 07:28 Go to previous messageGo to next message
John Watson
Messages: 7263
Registered: January 2010
Location: Global Village
Senior Member
Welcome to the forum. Please read our OraFAQ Forum Guide and please read How to use [code] tags and make your code easier to read

The package is not documented, and as you have discovered attempting to reverse engineer its functionality may give apparently inconsistent results. Can you not use the supported interface, which is to create a dbms_advisor task?

--update:
I just had a look at the source code for the package, this might be significant:Quote:
FUNCTION rbu_migration RETURN NUMBER;
-- This functin returns required undo tablespace size if users want to
-- migrate from rbu to aum. This function should be called only when
-- undo management is manual.

-- Input Parameters:
-- starttime: Start time of the given period.
-- endtime: End time of the given period.


[Updated on: Tue, 29 April 2014 07:42]

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icon14.gif  Re: UNDO MANAGEMENT [message #613078 is a reply to message #613073] Tue, 29 April 2014 07:59 Go to previous message
silas.silva@gmail.com
Messages: 2
Registered: April 2014
Junior Member
Thanks John, I believe that I can create the task in Enterprise Manager, to estimate the size. In my case the parameters UNDO_MANAGEMENT=AUTO and UNDO_RETENTION=900, and my UNDO tablespace is growing very fast. I believe that i have to resize it.
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