Re: Normalization

Dear Bill

On Thu, 29 Jul 2004 12:09:23 -0600, Bill Sable <daniel.fink_at_sun.com> wrote:
> I recall a quotation to the effect that no database will perform adequately
> in 3rd Normal Form. To me this defines the difference between theory and
> reality. I have had the 'pleasure' to deal with 2 separate 'datawarehouses'
> that were exact copies of the OLTP structures. They work fine for a few
> months, then performance *rapidly* degrades to the point where the system is
> basically useless.

As I think others have said, designing for a true DW situation may well involve a different set of disciplines than OLTP design. (Of course it may not). If a DW system really is an exact copy of the online system, then I'd be very tempted to ask why it was being built. If the OLTP system can already meet all your reporting needs in an adequate way why build a new system - if you really need to offload work to some other server then standby or even that three letter acronym beginning with R might be appropriate.

I've always thought, been taught, that you design for OLTP etc in 3NF, you then (in an unsurprisingly close model of the hotsos tuning approach) see how the critical business processes perform, and if they don't meet your requirements then and only then do you denormalize, and you stop denormalizing when your code performs to spec.

I have to confess I haven't seen many systems like this, so maybe the original suggestion is closer to current business practice.

-- 
Niall Litchfield
Oracle DBA
http://www.niall.litchfield.dial.pipex.com
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