Re: recovery and resetlogs

From: Sybrand Bakker <postbus_at_sybrandb.demon.nl>
Date: Thu, 23 May 2002 18:09:17 +0200
Message-ID: <ueq7ov6uelhe64@corp.supernews.com>

"Charles J. Fisher" <cfisher_at_rhadmin.org> wrote in message news:Pine.LNX.4.44.0205230944170.14395-100000_at_galt.rhadmin.org...
> I have a question regarding instance and database recovery and their
> interaction with a resetlogs operation.
>
> I understand that instance recovery is a two-phase process, where SMON
> first rolls-forward all redo, opens the database, and then goes into a
> low-priority background state and rolls-back all uncommitted redo.
>
> However, when the database is recovered from backup datafiles without
> online redo logs (by rolling through archived logs), and the database is
> opened with a resetlogs operation, how does SMON know about the
> uncommitted transactions?
>
> I imagine that rolling-forward through the redo built all required
> versioning blocks in the rollback segments, but when all redo records are
> erased, how does SMON still retain knowledge of uncommitted transactions?
>
> ----------------------------------------------------------------------

---

> / Charles J. Fisher |"How many who came into this
world /
> / cfisher_at_rhadmin.org | with me have already left it!"
/
> / http://rhadmin.org | -Marcus Aurelius
/
> --------------------------------------------------------------------------
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>

Uncommitted transactions are in *both* the online redolog *and* in the rollback segments. A rollback segment is stored in a datafile. Does that answer your question?

Hth,

--
Sybrand Bakker
Senior Oracle DBA

to reply remove '-verwijderdit' from my e-mail address

Received on Thu May 23 2002 - 11:09:17 CDT