| UNDO tablespace: how to shrink datafiles ? [message #347221] |
Thu, 11 September 2008 02:06  |
psoftneto
Messages: 44
Registered: July 2008
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Hi all,
Please can some one tell me how to shrink UNDO tablespace datafiles ?
Even after shutdown/startup the datafiles still have the same percentage of use.
Will those datafiles shrink automatically when user will make a new request ?
Thanks for your response.
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| Re: UNDO tablespace: how to shrink datafiles ? [message #347433 is a reply to message #347235] |
Thu, 11 September 2008 11:34  |
macdba
Messages: 27
Registered: May 2005
Location: US
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Junior Member |
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UNDO TS remains occupied till undo_retention. When new transaction requires a space, transaction which are expired are removed from undo segments and space is made is available. By default Oracle does not guarantee undo retention.
In 10G there is parameter undo_retention_gurantee this one guarntees undo retention. So check if it is set. If there is no space available in UNDO and old segments are not expired, new transactions will abort.
You dont need to shrink the UNDO segments like the old rollback segments if the undo management is AUTO
regards
--Mak
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