Re: how rollback segment is used

"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 - 06:27:27 CST