Re: Increase the size of rollback segments

"Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in message news:971808412.11363.0.nnrp-10.9e984b29_at_news.demon.co.uk...
>
> If you have a 1MB rollback segment, it may be
> recycled several times without being written to
> disc. If you have a 100MB rollback segment
> then you will probably write the whole thing
> out before you get round to recycling it.
>

I'm probably being rather dense, but I can't quite see the logic here.

You're saying small segments will never flush to disk, but big ones will in their entirety?

Nope... Can't for the life of me see why that should be so. Can you elaborate please, because I suspect I'm missing something fundamental here.

Regards
HJR
>
> --
>
> Jonathan Lewis
> Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk
>
> Howard J. Rogers wrote in message <39ec377a_at_news.iprimus.com.au>...
> >Can you explain what the IO cost is? Cos I can't think of one.
> >
> >Regards
> >HJR
> >--
>
>--------------------------------------------------------------------------
> >Opinions expressed are my own, and not those of Oracle Corporation
> >Oracle DBA Resources: http://www.geocities.com/howardjr2000
>
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> >
> >"Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in message
> >news:971718991.1058.0.nnrp-08.9e984b29_at_news.demon.co.uk...
> >>
> >> The problem isn't one of space - like you, I am quite happy
> >> to 'waste' empty space to make administration more straightforward.
> >> In the case of rollback segments, though, there is an I/O cost
> >> to large rollback segments that can be avoided by keeping the
> >> rollback segments at the optimal size.
> >>
> >> --
> >>
> >> Jonathan Lewis
> >> Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk
>
>
>
Received on Wed Oct 18 2000 - 04:50:20 CDT