Re: PIZZA time again :-)
Date: Sat, 10 Sep 2005 13:02:23 +0200
David Cressey wrote:
> Marshall Spight wrote:
>>Although for the purposes of data modelling, I don't see >>that the order is relevant. The fact that the person who >>makes the pizza puts the toppings on in a certain order >>doesn't mean that order is relevant to how you specify >>a pizza. I've never heard anyone ordering pizza say >>anything like "please put the pepperoni down first, >>then the cheese." It's just "pepperoni and cheese" and >>its up to the person making the pizza to use the correct >>order.
> I've already rested my case, so I'm not about to reenter the argument. But,
> since you're the "semantics guy" in this forum,
> I can't resist bringing up the question of semantics, implicit in the topic
> Here it is, all the way back to the beginning of the topic.
>>Assume >>1. there is a meaningful (or at least consequential) >>difference between: >> >>toppings([salami, mozarella, onions]). >>and >>toppings([mozarella, onions, salami]).
> That word "meaningful" should be a clue that, ultimately, what we're
> discussing here is semantics.
Yes. And even earlier:
The word "assume" aks the reader to take what is assumed as given, so we can get to the question at hand.
A lot op the postings just go into wether the difference in the
example could actually be meaningful.
What is bothering some people about the assumption is of course (rephrased from Marshall Spight's statement that it isn't in this case):
"For the purposes of data modelling, order can be relevant."
IMO below you make a strong case that it can.
> The first question is, "meaningful in what context?"
> In terms of databases, there are at least two contexts: the context of the
> transaction that wrote the data, and the context of any transaction that
> reads the data. So the question is not "meaningful in use" but "meaningful
> in exchange".
> The "obvious exchange" to me is the case where someone orders a Pizza from
> a delivery store (I just happened to use Domino's as an example), and
> orders a set of toppings. A while later, the delivery man shows up, the
> customer looks in the box, and says "this isn't what I ordered". The
> delivery man looks in the box, looks at the order, and says "yes, it is."
> The customer grabs the order out of the delivery man's hand and looks at it
> and it says,
>>toppings([mozarella, onions, salami]).
> whereupon the customer says, "what I actually ordered was,
>>toppings([salami, mozarella, onions])."
> And the delivery man says, "well, it's the same thing.".
> Now, I don't care whether the cook always adds the ingredients in a set
> order or not. All I care about are the context of the order and the context
> of the delivery.
> So, to make a long story short, the question of "is it a list or a set"?
> boils down to "what are you going to do with the data"?
> This question is relevant to data modeling as well as to process modeling.
Received on Sat Sep 10 2005 - 13:02:23 CEST