Re: identifying entities across database updates (was: Is a function a relation?)

"Walter Mitty" <wamitty_at_verizon.net> wrote in message news:OTh3m.554$P5.167_at_nwrddc02.gnilink.net...
>
> "none (Reinier Post)" <rp_at_raampje.> wrote in message
> news:4a4d30b3$0$8961$703f8584_at_news.kpn.nl...
>> Brian Selzer wrote:
>>
>>>I accept as an axiom that there are objects that can have a location in
>>>time
>>>or space. To formalize this, let C! be a 1-place relation that ranges
>>>over
>>>the objects in the Universe and expresses the property of having a
>>>location
>>>in time and space--that is, being concrete.
>>
>> Wait. Assuming that objects exist doesn't imply that we can uniquely
>> identify them. You and I, or even I and I, may very well disagree on
>> how to partition the universe into objects, depending on the purpose of
>> our description. How many objects is a chair? How many objects is
>> the character A? Can it be green? Is the chemical element C an object?
>> Is course 430, Database Design and Administration at Moron University,
>> an object? The reconciliation of different, overlapping database
>> schemas, even within the same organization, is an important practical
>> problem. So your relation is rather big. It certainly isn't a normal
>> database relation.
>
> [snip]
>
>> I don't think so. Why are you holding it, then? You may be
>> confusing database tuples with objects in the OO world.
>> The difference is in the nature of the relationship between
>> attribute updates and the object being modelled.
>>
>> In an OO fishtank, setting the 'healthy' property of a fish
>> to '+' will actually heal the fish! In a database, unless
>> we have some really unusual user-defined types inside, it will
>> do no such thing, but will only change our *statement* on
>> the health of that fish. This is why it's useless to regard
>> our database tuples as 'really' standing for identifiable objects:
>> we can only do that to the extent that we can actually identify
>> these objects by the tuple's attribute values.
>>
>> --
>> Reinier
>
> Among Hindu mystics, the division of the universe into objects is itself
> an illusion. It might be considered "the first great blunder" of someone
> who would understand ultimate reality.
>
> http://en.wikipedia.org/wiki/Maya_(illusion)
>

In a wonderful illustration of reality and illusion, my newsreader took the close parenthesis in the above URL to be not part of the URL. So when you follow the link, you get taken to the Wikipedia page for "no such article". To get to the actual article, you may have to manually correct the URL before you follow the link. I couldn't have engineered a better illustration of the subjectivity of data. Received on Fri Jul 03 2009 - 09:01:47 CEST