Re: The wisdom of the object mentors (Was: Searching OO Associations with RDBMS Persistence Models)

From: Sasa <>
Date: Mon, 05 Jun 2006 19:36:33 +0200
Message-ID: <e61q2i$o4i$>

Marshall wrote:
> Sasa wrote:

>>mAsterdam wrote:
>>>And all tables, columns and constraints in your schema
>>>were designed and named by the object-persistence layer
>>>designers/programmers, for programs.
>>No. They should be designed semi-independently of the object persistence
>>layer. The client (app(s)) dictates what it wants. The DBMS chooses how
>>will it present it. The mapper, simply translates.

> Why would you do that? The requirements dictate the conceptual
> model. The conceptual model dictates the logical model. The
> logical model is the database schema. The conceptual model
> also dictates what the application code needs to do.
> If you have done the above correctly, there is no "separation"
> between the schematic needs of the database and those
> of the application. There is certainly no need for "independence."

Given the fact that same model is described in OO and relational world, one using things such as classes, class hierarchies and aggregations, and the other using tables. Is it not to be expected that there will be difference in each design?

Of course, they are both driven by the same model, with the possible option that the database describes broader model if it serves more than one applications. Hence the semi independence.

Sasa Received on Mon Jun 05 2006 - 19:36:33 CEST

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