RE: backup UNDO Tablespace (dba_undo_extents)

From: Powell, Mark <>
Date: Tue, 15 Dec 2009 17:22:37 +0000
Message-ID: <>

The undo tablespace is definitely required for full recovery of the database. First your restore then you roll forward then you rollback at the end to create a consistent image.

What kind of rman backup is being used? Backup pieces or copy, full or incremental, etc ... I expect at some point the full undo tablespace was used hence the full tablespace data files get backed up.

From: [] On Behalf Of MacGregor, Ian A. Sent: Tuesday, December 15, 2009 12:08 PM To:
Cc:; Subject: Re: backup UNDO Tablespace (dba_undo_extents)

The undo tablespace is required for database recovery

Sent from my iPhone

On Dec 15, 2009, at 8:51 AM, "Guillermo Alan Bort" <<>> wrote:

Short answer... don't take a backup of the undo tablespace... it's not required for database recovery.


On Tue, Dec 15, 2009 at 1:20 PM, Roger Xu <<><>> wrote: Good morning,

Background: Windows 2003 / Oracle 10g with auto undo (8K block size)

We have only one datafile (20 GB) in the undo tablespace. When I ran RMAN backup of this datafile, it created a 20GB backupset file.

I query dba_undo_extents and it shows less than 80 MB used.

SQL> select sum(blocks) from dba_undo_extents; SUM(BLOCKS)


Any explanation? How do I keep the backup of undo small?

Roger Xu

-- Received on Tue Dec 15 2009 - 11:22:37 CST

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