Re: In an RDBMS, what does "Data" mean?

Anthony W. Youngman wrote:

> mAsterdam writes

>> Anthony W. Youngman wrote:
>>> mAsterdam writes
>>>>>> R 'loses the ability to view the data' from within M and that
>>>>>> would somehow mean M is *more* expressive?
>>>>>> The only way I could make sense out of that is
>>>>>> if the (appearant) excess expressions in R could
>>>>>> *not* be relevant to a solution.
>>>>>>
>>>>>> Do you have an indication as to what those excess expressions are?
>>>>>
>>>>> they tend to be data that were collected and stored  
>>>>> in the M solution and designed out (deemed unimportant
>>>>> to retain) for the R solution.
>>>>
>>>> Just to get it straight: These 'designed out' data *can*
>>>> be represented in R (inferred from the R translation of the M 
>>>> solution), but they are *not* represented in R because of the 
>>>> different design  process (ispired by the nature of M cq. R)?
>>>
>>> Yes. Because M has retained metadata (which it can 
>>> express as data in R).
>>> But R may not be able to express that in M because the analyst 
>>> didn't view the metadata as important.
>>
>> It is R or it is the analyst who did not view the metadata (and it 
>> would help if you could narrow it down by being more specific - I 
>> think there is a lot of metadata that you falsely exclude) as important.
>> I would say it's the analyst, maybe - somewhat- inspired
>> by the language she uses.

Are these really the only alternatives? Let me guess. Analysts usng a RDBMS have to be perfect to get it right, but MV automagically stores everything possibly relevant.

>>> And even where R expresses an M-like view of the data, it contains 
>>> less  INFORMATION, because R is unaware that it is expressing metadata.
>>
>> So now languages should be aware of what they are expressing.
>> Why this mixing, IMO unnecessary confusing way of saying things?
>>

Any other complaints about that? Not from me. I suggest that if MV does not convey all relevant data, MV is not good at expressing itself clearly.

> But let's go
> back to the "list or bag" thing. If both the MV and the relational
> database contain the *same* data, then the MV version is richer because
> it has retained any order that was there.

Why not convey it explicitly, if it is relevant?

> If the app wants a bag, it can
> ignore the order. But if the app wants the original list, not only does
> the relational version have to store more data, but it has to do more
> with it - it has to sort it before handing it back to the app. The app
> needs to know that it's supposed to be a list, and also has to know how
> to convert the set back to an ordered list.
>
> That's what I'm trying to express - a lot of stuff is implicit in the MV
> approach, which you can ignore if you want. By explicitly forcing this
> metadata into data, a relational app needs to "know" a lot more to get
> the same result.

All data expressible in R is expressible in M. True? Received on Thu Jun 24 2004 - 01:14:38 CEST