Re: By The Dawn's Normal Light

Marshall Spight wrote:
> This conversations takes as a given that there's a
> "relation engine" and a *separate* entity, the "type
> engine." I've not heard this terminology outside
> of this list. Can someone explain what the value of
> separating these two entities is?

I think it might be some terminology that I've made up. It's often said that "types and relations are orthogonal" (google this newsgroup for example) and this is just expressing that idea.

It seems neatest to me to consider the part that does the relational stuff as a separate system to the part that does the type/domain stuff. It's like they are encapsulated from each other and interact only through well-defined interfaces.

I think it's crucial when considering what is meant by "first normal form" and "atomic", for example.

I've not written a DBMS so I'm only guessing, but I'd imagine the relational implementation would divide quite naturally from the implementation of the types/domains.

But it makes sense to me to think about it from both a logical and physical point of view.

The idea is that people should be able to write their own type implementations and add them to a relational core. How easy this is I'm not sure and I think it's difficulty might be underestimated, but it would fit with the idea of separating out the two.

Paul. Received on Mon Nov 08 2004 - 22:15:09 CET