Re: Logical equivalence of simple and complex types under the relational model?
Date: Tue, 30 Nov 2004 21:02:07 +0000
Message-ID: <41acdfd0$0$9345$ed2619ec_at_ptn-nntp-reader02.plus.net>
Rene de Visser wrote:
>> If the DBMS has a function that returns the integer part of a
>> float, this means that float is a complex type?
>
> I was wondering about such things myself. What if you have a function
> that returns that the nth bit of an integer? Or allows you to do
> prime decompositions of a number?
>
> I am not sure that the split between complex and simple is well
> defined at all. Especially if the DBMS allows user defined functions
> that can operate on the phyiscal level...
The way I see it, DBMSs consist of two (orthogonal) components: a type system and a relational system. If the DBMS can decompose a value using the relational system alone, it's a complex value. If it needs the help of the type system to decompose the value, it's a simple value.
Like most things, "complex" and "simple" are relative terms. To the type
system pretty much all values are complex. To the standard relational
system, all values are simple.
Paul.