On Dec 15, 2005, at 2:19, Darren Duncan wrote:

* a Tuple is an associative array having one or more Attributes, and each Attribute has a name or ordinal position and it is typed according to a Domain; this is like a restricted Hash in a way, where each key has a specific type

* a Relation is an unordered set of Tuples, where every Tuple has the same definition, as if the Relation were akin to a specific Perl class and every Tuple in it were akin to a Perl object of that class

Something that puzzled me in "Database in Depth" is that jargon, supposedly math-based. A relation in math is just a subset of a Cartesian product, and a tuple is an element of a relation. So it's standard for a Relation type to be a set of Tuples, but a tuple itself is not a set (as are "tuples" in the book, argh). So if something unordered like that goes into the language to mimick that model I wouldn't call it Tuple.

Math conventions there are well established, the jargon in "Database in Depth" departs from them and I don't think it is a good idea to adopt it.

-- fxn

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