Re: Lucid statement of the MV vs RM position?

Bob Badour wrote:
> Marshall Spight wrote:
>> Can you be more specific about the differences between the
>> two?
>
> In the end, I think you and I focused on function while Jon focused on
> form.

I think not. I focus on the significant difference between

1. An aggregate operator
2. The invocation of an aggregate operator within a SUMMARIZE operator

You don't get from relation (1) to relation (2) in my post to Marshall just by using SUM. You have to use SUMMARIZE as well.

For that matter, I don't think neither you nor Marshall really have focused on anything but saying "Yes, it is!". You don't address my arguments at all.

> Functionally, GROUP is an aggregate among other things.

(An *aggregate*? Or an aggregate *operator*? Do you mean to distinguish between those terms?)

No. Functionally (I'm not sure what precisely that means, but...) it can be defined *using* an aggregate. (But you don't have to define it that way).

Is "SUMMARIZE R BY A ADD (SUM(X) AS AGG_X)" an aggregate (operator?)? Is it the aggregate operator SUM?

Is "SUMMARIZE R BY A ADD (SUM(X) AS AGG_X, AVG(Y) AS AGG_Y)" an aggregate? Which aggregate operator is it?

Is "SUMMARIZE R BY A ADD (UNION(RELATION{TUPLE{X}}) AS AGG_X)" an aggregate?

> For instance, it is also a value selector.

I'm not sure what you mean by this term.

> Syntactically, Date and Darwen chose to handle it differently than other
> aggregates. Perhaps to avoid confusion with the UNION aggregate,

But isn't D&D's UNION aggregate precisely what you claim GROUP is? Or do you actually claim that an aggregate operator is *both* the operator itself (defined by identity and repeated operation) *and* a SUMMARIZE invocation using the aggregate operator as a summary (and presumably no other summaries, cf. my SUM/AVG example above)?

> or
> perhaps to provide a symmetric balance to UNGROUP. Perhaps for a lot of
> reasons or perhaps for no particular reason.
>
> One can easily look at GROUP as a convenient shorthand for a combined
> type conversion and aggregate.

No, you need a "surrounding" SUMMARIZE as well.

-- 
Jon