Re: Relational vs network vs hierarchic databases

"Ja Lar" <jalar_at_nomail.com> wrote in message news:cmqh96$9e2$1_at_news.net.uni-c.dk...
>
> "Laconic2" <laconic2_at_comcast.net>...
>
>> Never mind what I said. Take a look at what Dan said. That kinda lays
> the
>> subthread to rest, I think.
>
> Yes. You (both) are talking about physical/implementation matters, not
> about
> relational model versus hierarchical/network model.

Not really. I could write a set of names on a piece of paper and connect them by arrows and traverse any given sequence much quicker than doing a sequence of tuple associative value lookups.

I can model a hierarchy and a network relationally. Is this what you mean? Or do you mean that some formal logical model could never be implemented using graphs or a special type of graph?

How do you talk about a hierarchical/network model (when you are really talking about systems) without talking about physical/implementation matters. That was the primary basis of criticism for why the relational model was superior (remember the term physical indepedence).

>
> In this case, you might be correct in one or more concrete cases. (But you
> might be wrong as well).

I'm not sure what you mean? "You might be right, but you might be wrong?" Care to be more concrete?

> Point is that "relational" and "performance" are orthogonal - and thus not
> contradicting or compeeting in any case.

What does orthogonal mean? Does it mean that the intersecting vectors of relational and performance never ever really intersect? No.

Why do we have an OSI model that divides the requirements of communication into seven layers, but rarely does a protocol stack consist of 7 layers when implemented? Because of the overhead. In theory, understanding things like processing overhead, delay propagation, jitter, signal to noise ratio, and other factors have real theoretical relevance, no matter what type of model is put out there.

Yes. The relational model is a logical model that is orthogonal to "performance" in the abstract. But if you are going to compare it to a hierarchical or network model and criticise those models for being constrained and hindered because of the use and dependence on pointers, which are physical, then their is no reason not to recognize their strengths in terms of their physical manifestion as well.

> In regard to the theme of the thread: that's the important message, IMHO.

OK

• Dan