Re: Object-relational impedence
Date: Thu, 6 Mar 2008 14:58:35 +0000
Message-ID: <slrnft01kr.ap4.eric_at_tasso.deptj.demon.co.uk>
On 2008-03-05, Dmitry A. Kazakov <mailbox_at_dmitry-kazakov.de> wrote:
> On Wed, 5 Mar 2008 11:34:05 +0000, Eric wrote:
>
>> On 2008-03-04, Dmitry A. Kazakov <mailbox_at_dmitry-kazakov.de> wrote:
>
>> I don't believe that merely using an RDBMS will solve all problems. What
>> I meant was that, accepting what David said above, if you keep your data
>> in an RDBMS, it will be easily available for the solution of any
>> possible problem that can be solved using that data.
>
> No, this as well is wrong. Keeping "data" in RDBMS puts certain
> restrictions on what can be stored there and how it can be used later.
No it doesn't, in either case.
>
> You propose a solution (DB on a RDBMS). What was the problem? From your
> description the problem looks like a persistence layer. This what c.d.t.
> people vehemently disagree. Isn't it interesting to see how quickly a great
> theory of all degrades to storage?
A persistence layer is "my program has X, I need put put it away somewhere and get it back later". As long as what you get back is what you put, it's OK - no need to worry about the internal details of X or what it might be related to.
An RDBMS is not a persistence layer. No-one from c.d.t has said that it can not be used as a persistence layer. What is often said is that using an RDBMS _merely_ as a persistence layer is a grossly misguided use of machine and human resources.
The relational model is not a great theory of all, it is a logically-based recipe for the long-term management of data. You are the sort of person who degrades it by arguing from a position of ignorance of what it is really about.
>
>>> I guess that his hidden argument was "because RDB
>>> apparently solves all problems, then data-centric view is the right one."
>>
>> No, the argument is that the data-centric view is often (not necessarily
>> always) the right one to take, and that keeping the data in an RDBMS
>> provides a better basis for solving future problems using the data than
>> any other way of keeping it.
>
> Ah, that's better. So data-centric view is not universal => then there
> exist cases which cannot be viewed that way => data is not a fundamental
> term => data do not unconditionally exist. Are we in agreement?
>
No we are not. "cannot be viewed" should be "are not best viewed", and the rest of your implications are nonsense.
>>> Yet another logical fallacy was a data-centric problem statement: "there
>>> will never be any other application that will need my data," used in order
>>> to prove data-centric view itself.
>>
>> There is no fallacy here. First there is a fact - you have data, however
>> you choose to view it. Do you want to deny this?
>
> Certainly. Non-observable things do not exist. But the fallacy is that you
> are putting existence of data as a fact from which you deduce data
> existence.
I have not deduced data existence from anything, I simply believe it to be a fact.
>
>>> In OO problems are not modeled in terms
>>> of applications using data.
>>
>> No, but the data is still there.
>
> In which sense? Laplace has answered this two hundred years ago: "I did not
> need to make such an assumption."
>
What is your definition of "data"?
E Received on Thu Mar 06 2008 - 15:58:35 CET