Re: Autoallocate vs Uniform extent performance

I totally agree Gaja.

I support a SAP BW system and they create tables with a 100 of partitions and only load 24 of them. With autoallocate, most of them are small (64k) and space is not wasted. If they do decide to load them up, I'm still safe because the extent size increase as the object grows.

I'm don't advocate of autoallocate for everything because I can't determine the next extent, but this is one place where it's better than uniform.

I also have some uniform LMTs for larger tables that I migrate to when tables get too big.

Steve

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Thursday, April 03, 2003 11:33 AM

> Totally agree with Connor. Just to add a comment to
> his note.
>
> A usage model recommended for UNIFORM vs. AUTOALLOCATE
> follows:
>
> If you know the data volume and growth of your
> segments and they are predictable, then use UNIFORM.
>
> If you are completely in the dark with:
>
> 1) How much data is going to be persisted in the
> segments?
> 2) What growth patterns the segments are going to
> exhibit?
>
> Then use AUTOALLOCATE.
>
> Of course, if you do change your mind, after the fact,
> you can use the MOVE command to the tablespace of
> choice with the extent allocation of your choice.
>
> Cheers,
>
> Gaja
>
> --- Connor McDonald <hamcdc_at_yahoo.co.uk> wrote:
> > I don't believe that was the case. auto and uniform
> > in all of the (admittedly rudimentary and
> > subjective)
> > tests I've done appear the same in terms of
> > performance.
> >
> > I prefer uniform purely for the reasons of:
> >
> > - more thorough elimination of fragmentation
> > - predictability of next extent sizes
> >
> > hth
> > connor
> >
> > --- Peter.McLarty_at_mincom.com wrote: > Hi all
> > >
> > > Some time ago there was a discussion about the use
> > > of the different extent
> > > management types and that if my memory serves me
> > > that there was a
> > > perception that Auto allocate extents had some
> > > performance issues against
> > > Uniform extents.
> > >
> > > Was this correct and can it be backed up with some
> > > definitive testing, has
> > > someone done a whitepaper???
> > >
> > > Cheers
> > >
> > >
> > > --
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Author: Steve Perry
  INET: sperry_at_sprynet.com

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