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Re: I think that relational DBs are dead. See link to my article inside

From: David Portas <REMOVE_BEFORE_REPLYING_dportas_at_acm.org>
Date: 20 Jul 2006 14:37:00 -0700
Message-ID: <1153431420.054503.62110@m73g2000cwd.googlegroups.com>


Josip Almasi wrote:
> >
> > What multidimensional model? Kimball popularised some methodology and
> > some jargon under the Dimensional banner. Some people find such
> > terminology useful but it doesn't change the data model. It is still
> > relational or SQL. Do you think relational is something other than
> > multi-dimensional?
>
> You really gave me some food for thought with this:)
> Yes, you're right. Only difference is normalization.

Not even that. The Kimball-styled "Dimensional Model" operates only at the logical level. Despite hype to the contrary it is orthogonal to normalization, not the antithesis of it. Normalization is concerned only with base relations whereas Kimball's ideas can be implemented purely through views without disturbing NF at all. RK has done a lot of ill by not better explaining the nature of his ideas. His works contain plenty of confusion over logical versus physical.

> > A recursive CTE. More generally speaking the query is just some
> > restriction of a transitive closure (ie. it need not be defined
> > recursively).
>
> But needs to be iterated regardless, right?
> If so, it's not relational.
> Please explain; I just don't understand how it can be represented as set.

The relational model does not exclude iteration. RM says nothing about how any particular operation is performed inside the DBMS. What matters is that the operation can be logically defined using only relational operators. The transitive closure of a graph is certainly a set. A subtree within that graph is just a subset of it. In the case of a hierarchy it is particularly easy to define a subset just by specifying the root of a subtree.

[dropped comp.ai.neural-nets from my reply]

-- 
David Portas
Received on Thu Jul 20 2006 - 16:37:00 CDT

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