RE: How to clear UNDOTBS

  • From: "Goulet, Richard" <Richard.Goulet@xxxxxxxxxxx>
  • To: <ecandrietta@xxxxxxxxx>, "ORACLE-L" <oracle-l@xxxxxxxxxxxxx>
  • Date: Mon, 18 Jan 2010 08:40:26 -0500

Eriovaldo,
 
    You as a DBA don't clear the undo tablespace any more, that is handled by 
Oracle and there are really a number of things that can hold onto undo for long 
periods of time.  The first is the setting of UNDO_RETENTION in your database.  
The second is how long the user keeps things in limbo land, namely not 
committing.  The next is what other sessions are interested in the rollback 
data that your storing.  I know that UNDO can get very large on some systems, 
almost being twice the actual database, but that's not your fault or that of 
the RDBMS, but the application designer and the end user.  As examples, one 
database that I managed some years ago had almost 2TB of data and 500MB of 
undo, while a PeopleSoft system was 10GB of data and 100GB of UNDO.  Go figure.
 

Dick Goulet 
Senior Oracle DBA/NA Team Lead 
PAREXEL International 

 

________________________________

From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of Eriovaldo Andrietta
Sent: Monday, January 18, 2010 8:28 AM
To: ORACLE-L
Subject: How to clear UNDOTBS


Hi, 

I have an UNDOTBS that is growin up.
How can I do to clear it ?

I don´t need data that is there saved.
I can restart writting the UNDOTBS again.

Regards
Eriovaldo


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