UNDO is not strictly stored in the REDO. It is stored in the rollback
segments, but because the rollback is written to, it is a change to the
datafile(s) that contains the rollback, that change is written as a
change-vector to the redo (for rollforward, not rollback, purposes).Which is
why you can do a massive rollback regardless of how many times the redo logs
have switched over.
- Original Message -----
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
Sent: Wednesday, May 21, 2003 1:52 AM
> Jared - Yeah, perhaps I wasn't clear. Perhaps a Seussian rhyme will
explain
> it better:
>
> The redo stores undo so the smon is able to undo the disk writes when the
> system crashed because your parents came home.
>
> Dennis Williams
--
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Author: Binley Lim
INET: Binley.Lim_at_xtra.co.nz
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Received on Tue May 20 2003 - 10:01:50 CDT
