Re: The wisdom of the object mentors (Was: Searching OO Associations with RDBMS Persistence Models)
Date: Fri, 09 Jun 2006 10:11:32 +0200
Robert Martin wrote:
> Keith H Duggar said:
>> Robert Martin wrote:
>>> Bob Badour wrote :
>>>> A logical data model provides the structure, >>>> manipulation and integrity for a formal system. A good >>>> logical data model imposes no particular structure on >>>> the data as a whole while it does provide a structure in >>>> which to represent data. In fact, the structure of the >>>> data itself depends largely on one's point of view. One >>>> drastically alters the appearance of any graph by >>>> starting at a different location and traversing the >>>> edges in different directions. >>> >>> I'm with you so far >> >> So you agree that, unlike a relational data model, an OO >> (Network) data model imposes expression bias? In other >> words, that it creates a asymmetric navigational structure >> that artificially makes some computations more difficult to >> express? And do you think this is good? If so why?
> Because it also makes some computations easier.
Which (or which types of) computations are easier?
> An application will often reform data into a
> non-relational structure that eases computation.
"non-relational" as a synonym to "navigational" or did you have something else in mind?
> I'll grant you that the structure may make other compuations
> more difficult. (e.g. it is easier to search a balanced
> tree than to insert).
> Yes, I agree, there is an expressional bias. Indeed that is intrinsic
> to one of the points I've been trying to make (through the loud bluster
> of insults). Applications want to see the data in the form that is most
> convenient to them. This means that the applications should not
> strongly depend on the relational format unless that format IS the most
> convenient form for them.
That goes rather hard the other way:
Consider "Applications should not strongly depend on a navigational format unless that format IS the most convenient form for them.": a matter of convenience for some applications at the cost of convenience for other applications.
This comes close to first come, first serve.
If a new idea is sound at some abstract
level it still has to be cost-evaluated
against (and possibly rejected just because of) the navigations in place.
[snip FS] Received on Fri Jun 09 2006 - 10:11:32 CEST