This whole relational and dimensional thing is so last year, that isn't what I was talking about at all. In fact, if you check out the white paper I wrote for Netezza (follow the link at the bottom), you'll see I'm advocating something I call "careless design." We have so much hardware, we don't have to knock ourselves out designing for performance. Well, not really, but we're getting there. No, I didn't mean relational as opposed to dimensional, they're both relational. They're the same thing.

So far as I can tell, the world is full of things like app servers that talk to relational database servers because the "business rules" in a relational database aren't really business rules at all, they're just these little things, call them business data rule-ets. The real brains live in the app servers. The reason is that data models are to opaque for most mortals to understand. Stakeholders can't talk this language and they can't even validate the results.

I can't believe that in 2004, all of out DW processes, ETL, BI, etc., still hook up directly to the physical models of databases. It's not only a huge maintenance cost, it is too limiting.

What we need instead is a unified conceptual model that is exposed to people and processes. And what I mean by a conceptual model is something like a steering wheel or accelerator pedal in a car.

In my last car, there was no cable connecting the pedal to a throttle. Rather, the force and depth of depressing the pedal was registered by some electronic sensors that communicated to the engine management system which them insured that both throttles, one on each side of the V-shaped engine, were opened at precisely the same instant by two identical servo motors. That pedal was a conceptual model of the accelerator. I could drive the car without knowing anything about the mechanism actually engaged.

The same is true of a steering wheel. You get in a car and drive it. You typically don't think about the actual steering mechanism, whether it's a rack and pinion or a big steering box with a worm and roller. In fact, in that same car, there was a planetary gear between the steering column and and the steering rack for the "active" steering feature. A steering wheel is a conceptual model. It shields us from the having to know about the physical components that actually drive the machine and gives us continuity over time.

That's what I was getting at. Can we represent business rules as artifacts in relational databases? Maybe. Can we define business rules using relational data modelling? I doubt it, it isn't expressive enough and it's too technical.