Re: Guaranteed Flashback Table

From: Stefan Knecht <>
Date: Wed, 30 Apr 2008 23:16:56 +0200
Message-ID: <>

Hi Charlotte

No need to go to 11g -- you can do this in 10gR2 as well -- take a look at the retention guarantee clause, which you can specifiy at tablespace level:


RETENTION GUARANTEE specifies that Oracle Database should preserve unexpired undo data in all undo segments of tablespace even if doing so forces the failure of ongoing operations that need undo space in those segments. This setting is useful if you need to issue an Oracle Flashback Query or an Oracle Flashback Transaction Query to diagnose and correct a problem with the data.



On Wed, Apr 30, 2008 at 10:01 PM, Charlotte Hammond <> wrote:

> Hi All,
> I'd like to have the option to flashback a few large-ish tables (NOT the
> whole database) to the start of a complex data manipulation operation.
> However I have no idea how long this operation will take so I have to set
> UNDO_RETENTION to a big value just to be sure. I'd prefer to be able to
> define a point at the start of the operation, and say "keep enough undo to
> go back here". Is there any such mechanism? (Only thing I could think of
> was to keep dynamically cranking up UNDO_RETENTION as the operation proceeds
> but that seems really messy).
> I'll probably just stick with the tried and trusted CTAS "backup" of the
> tables before I start but just wanted to check that I'm not missing out on
> something that could save me time and space.
> Any suggestions welcome - thanks!
> Charlotte
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Stefan P Knecht
Senior Consultant
Infrastructure Managed Services

Trivadis AG
Europa-Strasse 5
CH-8152 Glattbrugg

Phone +41-44-808 70 20
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Received on Wed Apr 30 2008 - 16:16:56 CDT

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