Re: Logical equivalence of simple and complex types under the relational model?

"Rene de Visser" <Rene_de_Visser_at_hotmail.de> wrote in message news:cofms4$vr$1_at_news.sap-ag.de...
> I have read a number of papers that discuss whether complex data types
> should be allowed under the relational model.
>
> What I haven't seen analysed is whether there is actually any logical
> difference (upto renaming/isomorphism) between the resulting models.
>
> It seems to me at first sight that
>
> 1) RM with simple types
> 2) RM with complex types
>
> are indistiguishable at the logical level.
<snip>
> If this is so why was there in the past debate about whether to allow
> complex types or not, when it seems in theory (and in at least some
> languages) it makes no logical difference?

All data can be accounted for either way, but there is typically not a mapping between metadata. So, even if there is no logical difference, there is a semantic difference that is significant.

--dawn Received on Mon Nov 29 2004 - 23:51:27 CET