Re: Normalisation versus optimisation

"Normalisation" belongs to the realm of a (logical) datamodel; "optimisation" to the realm of physical implementation.

Anyone assuring you that you optimise performance by denormalisation is on thin ice! (Remember, this is comp.databases.theory :-) ).

My advise: don't denormalise, but if needed: use some physical optimisation, such as an index.

Regards
Jan Emil Larsen

"Edward64" <edward.collier_at_techop.co.uk> skrev i en meddelelse news:74bed22a.0110250616.7887c6d7_at_posting.google.com...
> Three tables: ProductType, ProductVariant and DespatchNumber.
>
> They enjoy a 1:n relationship, left to right e.g.
>
> ProductType -> ProductVariant, ProductVariant -> DespatchNumber
>
> The design of the tables is simple enough:
>
> ProductType =
> ProductTypeID, (PRIMARY KEY)
> ProductTypeDescription
>
> ProductVariant =
> ProductVariantID, (PRIMARY KEY)
> ProductVariantDescription,
> ProductTypeID (FOREIGN KEY on ProductType TABLE)
>
> DespatchNumber =
> DespatchNumberID, (PRIMARY KEY)
> DespatchNumberDescription
> ProductVariantID (FOREIGN KEY on ProductVariant TABLE)
>
> My question is this. Should I include the following column in
DespatchNumber table:
>
> ProductTypeID (FOREIGN KEY on ProductType TABLE)
>
> Is there any upside or downside to this? Normalisation versus
optimisation.
>
> The target database is SLQ Server 7.0
>
> TIA
>
> Edward
Received on Tue Dec 04 2001 - 08:10:38 CST