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Re: Stored fields ordered left to right

From: Paul G. Brown <paul_geoffrey_brown_at_yahoo.com>
Date: 28 Dec 2003 12:30:25 -0800
Message-ID: <57da7b56.0312281230.38fe4ded@posting.google.com>


"Bob Badour" <bbadour_at_golden.net> wrote in message news:<wLadnalFBMpQAXOi4p2dnA_at_golden.net>...

> For anyone who doesn't know, ignore Dawn--she's an idiot. Mathematical
> relations do not have any particular attribute order. The physical
> representation of mathematical relations using written symbols on planar
> surfaces relies on physical order for succinctness.

 Not quite right, Bob.

 Mathematical relations *do* have an attribute order[1] (or else the term 'mathematical relation' is used in another context entirely: to refer to relationships between maps [can't find a cite]). One of the ways in which Codd's relational model distinguishes itself is that it names relation attributes and thereby does away with the need for ordering. Some interpretations of the relational model retain the attribute order property(Datalog, for example[2]) or require the use of an index offset as an attribute identifier[3].

 Mind you, multi-value data management systems don't comply even in spirit with any of these models.

 See:

  [1] http://en.wikipedia.org/wiki/Mathematical_relation

  [2] http://www.cs.buffalo.edu/~chomicki/635/datalog-h.pdf

  [3] Abiteboul et al. _Foundations_of_Databases_ Addison-Wesley Publishing Company. 1995. (Specifically comments on the 'named' verse 'unnamed' perspectives in Section 3.2) Received on Sun Dec 28 2003 - 14:30:25 CST

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