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Re: how rollback segment is used

From: Daud <daud11_at_hotmail.com>
Date: 20 Nov 2002 20:09:27 -0800
Message-ID: <f0bf3cc3.0211202009.3d6f5f3d@posting.google.com>


Hi Richard

Thanks for your reply. Just one last clarification. So, if my last extraction finished (commited and done!) at extent number N, the next extraction will start at extent number N+1 and so on... (assuming there are no other transactions). Forget about other rollback segments because the extraction script is specifically told to use RBS01. Am I right?

rgds
Daud

"Richard Foote" <richard.foote_at_bigpond.com> wrote in message news:<H6KC9.80494$g9.226874_at_newsfeeds.bigpond.com>...
> "Daud" <daud11_at_hotmail.com> wrote in message
> news:f0bf3cc3.0211200239.7fbb5140_at_posting.google.com...
> > We have a reporting database that is separate from the production
> > database.
> > The ONLY inserts/updates/deletes that happen in the reporting database
> > come from a extraction script. Here is how the extraction script
> > works:
> >
> > Every 5 minutes, it wakes up, reads from a config file and extracts
> > data from production database and commits them into the reporting
> > database. The only thing that matters in the config file is the
> > parameter for rollback segment - we have to specify one specific
> > rollback segment - in this case RBS01.
> > Once the extraction is done, it sleeps and repeats the whole process
> > again one or two minutes later.
> >
> > My question is, will it ALWAYS start using from the FIRST extent in
> > the rollback segment and overwrites the previous extraction rollback
> > info?
>
> Hi Daud
>
> No.
>
> The extents in a rollback segment are used in a round robin manner. It will
> only write to the first extent again once it has been around and written to
> all the other extents (unless of course there is a blocking transaction in
> the first extent which prevents Oracle from overwriting it and causes Oracle
> instead to allocate a new extent).
>
> Your extraction script will start from the location within the rollback
> segment Oracle is currently up to and will only begin overwriting previous
> extraction info once it's written to all extents.
>
> Cheers
>
> Richard
>
> >
> > rgds
> > Daud
Received on Wed Nov 20 2002 - 22:09:27 CST

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