Re: Undo Retention of 5 days; anyone?

  • From: "Indy Johal" <Indy.Johal@xxxxxxxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Fri, 13 Feb 2004 11:03:27 -0500

Arup
Here is small cut out from one of the Oracle Openworld presentation title" 
ORACLE DATABASE 10 g TIME NAVIGATION: HUMAN ERROR CORRECTION"  by Tammy 
Bednar from Oracle

"New in Oracle Database10g is the ability to query data in the past for 
more than 5 days if the UNDO_RETENTION is set for greater then 5 days. 
Oracle will maintain the undo for that period of time as long as the Undo 
Tablespace datafiles are allocated enough disk space"

Now I am surprised with the result mentioned by one of the expert in 
earlier email in the list that he tested it with more than 5 days. The 
only exception I can count is
-->either  if the database is down for few days and then in that case 
SMON_SCN_TIME can have timestamp for more than 5 days
OR
--> If the SCN flashback method is used and not the Timestamp.


Also the Timestamp Mapping to SMON_SCN_TIME are been referred at lot of 
places like here is one of the presentation link
http://www.aoug.at/Files/doag2003_x.pdf

Also this is been mentioned by Kirti in one of his presentaion slide named 
" Back to th past with Oracle 9i Flashback query"



Thanks

Indy Johal
Manager, Database Administration
PR Newswire
indy_johal@xxxxxxxxxxxxxx
http://www.prnewswire.com

(201) 946-5687 [W]
(201) 400-3960 [M]

"We tell your story to the world."




"Arup Nanda" <orarup@xxxxxxxxxxx>
Sent by: oracle-l-bounce@xxxxxxxxxxxxx
02/12/2004 10:16 PM
Please respond to oracle-l

 
        To:     <oracle-l@xxxxxxxxxxxxx>
        cc: 
        Subject:        Re: Undo Retention of 5 days; anyone?


Indy,

Thanks for the update on the SCN time limitation. I wasn't thinking about
that. If you do find some information on that limitation, I'll appreciate 
if
you could please share that with me.

The theretical limit of undo_retention is some 136 years!

Thanks.

Arup


----- Original Message ----- 
From: "Indy Johal" <Indy.Johal@xxxxxxxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Thursday, February 12, 2004 4:27 PM
Subject: Re: Undo Retention of 5 days; anyone?


> Arup
> If I am correct, can we go beyond 5 days of Flashback recovery using
> Timestamp method in Oracle 9i. I know somebody referred earlier in the
> mail that he recover the data which is older than 15 days. I know that
> some documentation says that it is not possible as timestamp mapping to
> SCN is maintained in SMON_SCN_TIME for only 5 days. I am not having any
> configuration to test it so thought I can check with you.
>
> Thanks
>
> Indy Johal
> http://www.prnewswire.com
>
> (201) 946-5687 [W]
> (201) 400-3960 [M]
>
> "We tell your story to the world."
>
>
>
>
> "Arup Nanda" <orarup@xxxxxxxxxxx>
> Sent by: oracle-l-bounce@xxxxxxxxxxxxx
> 02/12/2004 12:42 AM
> Please respond to oracle-l
>
>
>         To:     <oracle-l@xxxxxxxxxxxxx>
>         cc:
>         Subject:        Undo Retention of 5 days; anyone?
>
>
> List,
> I have a very unusual request from users to have UNDO_RETENTION set to 5
> days. Normally I set to about 5 hours, not days. Don't ask why. They 
have
> inherited a bad design that requires flashing back to 5 days ago and, 
no,
> they can't redesign it.
>
> I'm curious if anyone has actually done it, i.e setting it to a very 
high
> value. Any input will be highly appreciated.
>
> Thanks a lot in advance.
>
> Arup
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