Re: some ideas about db rheory

From: none <rp_at_raampje.>
Date: 04 Aug 2009 00:14:17 GMT
Message-ID: <4a777d59$0$25868$703f8584_at_news.kpn.nl>


vldm10 wrote:

>On 20 srp, 23:09, rp_at_raampje.(none) (Reinier Post) wrote:
>> I am afraid I do not see the difference.
>> I wrote that reply to ask you what the difference is.
>
>Given that I have spent much time working on this paper, constructive
>criticism is always welcome. Your comments, however, are more often
>intended as degrading than constructive.

I do not intend to degrade. I only try to understand the relationship between your proposed model and the relational model. It seems to me that it can be formalized in such a way that your model can be thought of as a way of using existing DBMSes, which would save a lot of work trying to understand or implement it.

>So I will reply on a lighter note.
>
>> Second, it seems to me that your use of identifiers
>> can be eliminated systematically and *losslessly*, i.e. without
>> diminishing expressive power.  I'm curious whether this is the case.
>
>No this is not the case, I will give you two examples:
>
>Example1. You need to make a db for a car dealer , who sells new
>Honda Civic vehicles. All of these vehicles are identical. If you
>eliminate the identifier, that is the VIN (vehicle identification
>number) it will be impossible to make a db (in the RM) for this
>dealer.

So this VIN is just a regular relation attribute for the Car relation. It is not something that requires you to go beyond the relational model.

[...]

>In real life 99 procent of business applications use identifiers. This
>happenms because IT professionals are ahead of IT theoretics. In my
>paper, you can find a theoretical background for identifiers.

OK. Now you're posting this in a newsgroup full of people who claim that identifiers are implementation details, funbdamentally wrong. etc. I am not even one of those people. I'm just asking how you prove them wrong.

>> You represent these 'meta-data' in a separate table and then link them
>> to the 'concept' using an identifier attribute.
>
>Since I have not mentioned the terms meta-data or table in my paper,
>please do not use them as mine, and then criticize me about them.
>I do not think that time or people are meta-data. It would do our
>discussion good if you gave us a drfinition for meta-data and data.

Data: facts regarding the state of affairs at the time they are asserted or retracted by a database change. Metadata: facts regarding such assertions or retractions, e.g. when they are made, or by whom. The distinction is necessarily interpretation dependent.

>Otherwise, I will not take you seriously. ( You can find a definition
>of data in my paper).

Fine.

>> I don't understand.  Suppose your database has an entity Person.
>> I am a person.  What is my identifier?
>
>You can try to follow your ideas and use your attributes strictly for
>your identification and representation.

?

-- 
Reinier
Received on Tue Aug 04 2009 - 02:14:17 CEST

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