Re: Guaranteed Flashback Table

  • From: Robert Freeman <robertgfreeman@xxxxxxxxx>
  • To: knecht.stefan@xxxxxxxxx, charlottejanehammond@xxxxxxxxx
  • Date: Wed, 30 Apr 2008 15:20:53 -0700 (PDT)

OF course, she could be on 9iR1 and then none of this makes a difference! :-)

 Robert G. Freeman
Author:
Oracle Database 11g New Features (Oracle Press)
Portable DBA: Oracle  (Oracle Press)
Oracle Database 10g New Features (Oracle Press)
Oracle9i RMAN Backup and Recovery (Oracle Press)
Oracle9i New Feature
Blog: http://robertgfreeman.blogspot.com (Oracle Press)



----- Original Message ----
From: Stefan Knecht <knecht.stefan@xxxxxxxxx>
To: charlottejanehammond@xxxxxxxxx
Cc: oracle-l <oracle-l@xxxxxxxxxxxxx>
Sent: Wednesday, April 30, 2008 3:16:56 PM
Subject: Re: Guaranteed Flashback Table

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:

From: 
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_7003.htm#i2231734

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.

Cheers

Stefan




On Wed, Apr 30, 2008 at 10:01 PM, Charlotte Hammond 
<charlottejanehammond@xxxxxxxxx> 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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-- 
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Stefan P Knecht
Senior Consultant
Infrastructure Managed Services

Trivadis AG
Europa-Strasse 5
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OCP 9i/10g SCSA SCNA
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