Re: The IDS, the EDS and the DBMS

From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Mon, 06 Sep 2004 23:21:43 +0200
Message-ID: <413cd4f4$0$42417$e4fe514c@news.xs4all.nl>

Alfredo Novoa wrote:

> mAsterdam wrote:

>>>>Why are these object-relational mapping projects bogus?
>>>>Is it because bridging the impedance mismatch is not a
>>>>worthwhile quest, is it because it it impossible or
>>>>just because none of these projects has done a good
>>>>job at it yet?
>>>
>>>It is because they eliminate the disease killing the patient.
>>
>>The patient being?
>>The disease being?
>>Let's try to properly pin-point the problems and the stuff
>>we'ld like to save.

>
> The patient is the SQL-DBMS, the disease
> the object-relational mismatch.

Very clear, thank you.

> The result is that you don't work with an SQL-DBMS anymore.

For an EDS, no real datasharing required, an SQL-DBMS might not be necessary.

>>>The solution is to include relation variables and the relational
>>>algebra/calculus in the application languages and not to hide the
>>>declarative set oriented DBMS behind a procedural record oriented
>>>layer.
>>
>>That would indeed be nice to have.
>>ISTM that is one way of trying to do object-relational mapping.

>
> What ISTM is?

Sorry. ISTM = It seems to me.

> ... We have that vocabulary. It is in the classic computer science books.

Classic as in pre-xxx? xxx being relational, object?

Laconics IDS/EDS distinction creates a frame of reference to discuss systems we have and can observe instead of discussing ideological rights and wrongs.

>>>The hide the power of The Relational Model forcing you to manage the
>>>data procedurally in the application.
>>
>>I'll try translating this into a less relational *versus* object 
>>version:
>>One thing the projects should not try to hide in hiding the 
>>complexity is the ease of operating at set-level.

>
> And using the set algebra/calculus.
>

>>Another no-hide thing is the power of declarative languages.
>>Am I understanding you correctly (for now dodging the implications)?

>
> Yes.
>

>>>>Trade offs are to be expected.
>>>
>>>And they are often impressive. The code size 
>>>grows in orders of magnitude.
>>
>>Yes. One nuance: Code is used more often than it is written,
>>so in widely used systems a part of this cost dissappears.

>
> No, the cost surplus never dissapears, but it is true that it may be
> little in percentage.
>
> For instance if you charge 8 million € for something that could be
> done for 100.000€ but you employ 2 million €, you still win a lot.
>
> I know cases like this. The low productivity
> helps a lot to hide the fraud.

True :-( but side-track, no?

>>The performance hit stays, evidently.

>
> But in most cases the performance hit is very negative.
>
> See this:
>
> http://martinfowler.com/articles/dblogic.html

ISTM (heh) that Martin Fowler knows his business. He knows his audience (OO students)
and how to not lose his audience in
giving advice: by prodding along at first.

>>While this does express your attitude,
>>it does not explain why (or where) the
>>relational interface would be
>>of just the right complexity.

>
> Because it is all in the books all we know, and I have no time nor the
> intention to type the whole books here :)
>
> But of course we can discuss any specifical point you want.

Ok, I'll hold you to this (as soon as I feel up to the challenge of being specific enough).

>>I think data sharing is not and should not be
>>the privilege of people with a sound knowledge of
>>"The Relational Model" (capitalization yours).

>
> I think that database system development should be the privilege of
> people with at least an elementary knowledge on the basics of the data
> management field.

Accidents will happen. When many cars are driven by untrained chauffeurs it is a certainty. I don't know how or when the need for drivers licenses emerged - hmmmm digressing again. Maybe we can analyse the clashes.

> By the way the capitalization is not mine, in
> English the proper nouns are capitalized.

It looked german (German?) and somewhat
putting it on a pedestal to me.
However, english is't native to me,
so I'll leave that to those who know better. Received on Mon Sep 06 2004 - 16:21:43 CDT