Re: cdt glossary - TABLE

Marshall Spight wrote:
> Jan Hidders wrote:
>

>>Note that a representation of a table in memory or on paper will always
>>necessarily introduce an order on the elements.

Actually I would argue it does introduce *some* order, just not the one we generally think of. The inverted index will have to be represented in memory so somehow so there will be a first entry, a second entyr, et cetera, and whith that entry there is a list associated, and combined these define yet again an order on the tuples.

>>This is similar to how
>>denotations of a set such as {a, b, c} and {c, b, a} also introduce each
>>a different order on the elements of the set. In the first denotation
>>the order is a < b < c, in the second it is c < b < a. This order,
>>however, is merely an aspect of the representation and not a property of
>>the thing that is represented. In other words, the two different
>>denotations actually represent the same thing.

Thank you.

>>For tables this means
>>that the order in memory of the representation of the body is not really
>>part of the body, or, put in another way, if we change that order in the
>>representation then it would still represent the same body.

Thank you, again. :-)

> Also: another attribute of any in-memory representation of a relation
> is that for each row, it will be possible to identify the specific
> chip it's on. Yet another attribute of the representation is total
> power consumption. Voltage. Position in space. etc. etc. None of
> these have anything to do with the value of the relation, though;
> along with order, we could change any and all of them, and still
> have the same relation value.

I like that. It really drives the point home and reassures the reader: "Look, this abstraction-thing is really nothing new, you are already doing it all the time, and this is not much different".

• Jan Hidders