Re: RM and abstract syntax trees

From: paul c <>
Date: Sat, 10 Nov 2007 18:31:44 GMT
Message-ID: <kOmZi.198054$th2.102454_at_pd7urf3no>

David Cressey wrote:
> The distinction between content based addressing and pointer based
> addressing is fundamental to the comparison of databases built on the
> relational model and databases built on the graph model.
> ...

That might be the most purely relational argument so far (versus ones that start with some programming technique and try to show that RM is comparable). You're in good company too - in 1970 Codd wrote:

"The simplicity of the array representation which becomes feasible when all relations are cast in normal form is not only an advantage for storage purposes but also for communication of bulk data between systems which use widely different representations of the data. The communication form would be a suitably compressed version of the array representation and would have the following advantages: (1) It would be devoid of pointers (address-valued or displacement-valued ) ."

(I believe he meant "array representation" to describe storage and by "communication" he didn't mean user interpretation, just data transport.   I imagine at the time among other things he might have had Cobol OCCURS clauses in mind and the file systems that allowed "null" interpretations. Wonder what he'd say today about the overhead, irregularity and ambiguity of XML.) Received on Sat Nov 10 2007 - 19:31:44 CET

Original text of this message