Re: Hierarchical Model and its Relevance in the Relational Model

Op vrijdag 30 januari 2015 14:23:48 UTC+1 schreef Derek Asirvadem:
> Jan
>
> Again, just on that one point.
>
> > On Friday, 30 January 2015 22:35:51 UTC+11, Jan Hidders wrote:
> >
> > As you know I agree with that to some extent, but not completely. So I wonder what arguments and observation you have to offer to support that position. And to avoid misunderstandings: I'm interpreting your position as that you think that the Nested Relational Model will lead to more effective DBMSs then the Flat Relational Model. Would that be fair?
>
> [.. snip ..]
>
> No. My initial post, this thread, is about real hierarchies.

And are these essentially different from nested relations? Can you define how exactly? Just so it's clear what you are talking about. I'm guessing it is that there is a notion of logical relationships between parts of hierarchies. But I'm not sure, so it would help the discussion if you could confirm that. I'm also curious what your evidence is that this has always been part of how the Relational Model was widely understood. I know database researchers who were around at the time, with both contacts in academia and industry, and they disagree with that.

> Not about the various papers that propose to implement data in some nested form (a view that is partially hierarchical) without understanding that the Relational Model has Hierarchies. ignorant people are forever re-inventing the wheel. and forever coming up short and square.

I don't know papers that talk about "implementing" in a nested form, but I do know papers about "representing" it that way. That is of course an essential difference if we take data independence into account. Why did you use the word "implementing" and which papers are doing that?

I also don't really get this accusation that these paper unfairly claim to have invented something new. As far as I can tell they usually don't do that; they rather investigate what happens if you do. Any paper in particular that you can point to that does this in a way you find unacceptable?

• Jan Hidders