Re: Hierarchical Model and its Relevance in the Relational Model

> On Thursday, 29 January 2015 22:39:37 UTC+11, Jan Hidders wrote:

I am too tired to write, but I am reading. Quick answer for now, on one point only. I will reply the rest tomorrow.

> Concerning B: It becomes important here what it is that you precisely mean with "the HM". If you include the traditional assumptions about how the data is stored and the pragmatics of how to effectively query and manage it, then, yes, that is pretty much dead.

Obviously. I think we all agree that it died /in that sense/ in 1984.

there are other senses.

> But most now understand the relevance of data independence.

Hah! you have to be kidding.

Please provide a single link to a paper written by a mathematician in the RDB space, that asserts that.

For each that you do provide, I will provide one that asserts the opposite. I would have thought that you are familiar with some of them.

For the few that do assert database independence, note that it has taken them forty five years to reverse their position. Practitioners who followed Codd, have never left that position.

That is precisely part of the problem I am saying, that contaminated and damages the RDB space.

> If you define the HM as only the idea that data can be nested, then as you know some promote the idea that the Relational Model should allow this and provide means to effectively deal with them.

No, I don't limit my idea of the HM (in the various senses it exists today, and as it influenced or was fundamental to the RM), to that sense. And there are other senses.

In scoping terms, let us exclude that: nested sets; nested relations; complex datatypes; issue from this thread.

I have already stated somewhere, I provide all that without the need to change the definition of atomic, etc, using todays SQL. But that too is out of scope. The reason I make that out-of-scoope point is, the supply that I provide is totally within the RM. That is to say, the RM does not need to "allow" full and complete handling of hierarchical data, it already does. And only an idiot (ie. one who does not understand the RM; one who does not understand Hierarchies independently; and one who does not understand Hierarchies as prescribed within the RM), would have to ask for that.

Further, those creeps that ask for such changes, cannot change the RM. It is not theirs to change. If their claims were valid, they should make up their own model. Of course, it would be a Toy Model, with rubber bands and popsicle sticks.

Once again, the damage that people who have private definitions, do.

Sorry for the short treatment.

Cheers
Derek Received on Fri Jan 30 2015 - 13:58:17 CET