Re: Mixing OO and DB

Bob Badour wrote:
> topmind wrote:
>
> > On Mar 17, 8:49 am, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:
> >
> >>topmind wrote:
> >>
> >>>On Mar 17, 5:21 am, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:
> >>
> >>>>topmind wrote:
> >>
> >>>>>Patrick May wrote:
> >>
> >>>>>>"Brian Selzer" <br..._at_selzer-software.com> writes:
> >>
> >>>>>>>"Patrick May" <p..._at_spe.com> wrote in messagenews:m2wso9i9be.fsf_at_spe.com...
> >>
> >>>>>>>>>> In any case, we're getting a little far afield from the
> >>>>>>>>>>original question. In enterprise systems, denormalization for
> >>>>>>>>>>performance does take place. This is just one of several reasons
> >>>>>>>>>>for decoupling the application logic from the database schema.
> >>
> >>>>>>>>>I don't agree with this. You're equating the database schema with
> >>>>>>>>>the database implementation.
> >>
> >>>>>>>> Not at all. I don't see where you get that from what I wrote.
> >>
> >>>>>>>>>The schema specifies what information is to be and can be recorded.
> >>
> >>>>>>>> Yes.
> >>
> >>>>>>>>>As such the schema is an integral part of the application
> >>>>>>>>>specification, and it cannot be decoupled
> >>
> >>>>>>>> No. One schema can support multiple applications, and often
> >>>>>>>>does in enterprise environments. One application can be supported
> >>>>>>>>by different schemas -- there is not one and only one way to
> >>>>>>>>represent the information required by the application.
> >>
> >>>>>>>I'll buy that a schema can be part of multiple applications, but
> >>>>>>>that there can be multiple ways to represent the same information
> >>>>>>>does not alter what information is to be and can be recorded.
> >>
> >>>>>> First, please excuse the delay in replying. I was busy
> >>>>>>destroying the world by replacing relational databases with in-memory
> >>>>>>distributed object repositories. ;-)
> >>
> >>>>>> We seem to be in agreement that different specific schemas can
> >>>>>>provide access to the same underlying information. That suggests that
> >>>>>>your statement that ". . . the schema is an integral part of the
> >>>>>>application specification, and it cannot be decoupled . . ." needs
> >>>>>>clarification. Would you agree with the formulation "The logical
> >>>>>>schema is an integral part of the application specification."? By
> >>>>>>"logical schema" I mean the implementation independent set of data
> >>>>>>that supports the application.
> >>
> >>>>>> If you agree with this, the second half of your claim ". . . and
> >>>>>>it cannot be decoupled" is clearly incorrect because the application
> >>>>>>implementation deals with the physical schema. Since you agree that
> >>>>>>multiple different physical schemas are possible, decoupling the
> >>>>>>application from any particular set of those is both possible and good
> >>>>>>design.
> >>
> >>>>>Decoupling adds a layer of indirection. Indirection is not free.
> >>>>>Unless that level of indirection buys you a lot, it is often not worth
> >>>>>it because it adds to maintenance cost and red-tape code bulk. Spend
> >>>>>indirection wisely.
> >>
> >>>>Topmind, if you are going to answer these idiots, please give better
> >>>>answers. As far as "decoupling" physical schema goes, the relational
> >>>>model already provides physical independence.
> >>
> >>>I think they mean things like pre-joined or pre-summed to how an app
> >>>"likes" it. I've worked on apps that often would benefit from a
> >>>simplified view of certain info for a particular app or group of
> >>>people.
> >>
> >>That's logical independence not physical independence, and the
> >>relational model already provides that too.
> >
> > Again, I don't think the originator literally meant disk sector bits.
> > But, I'll await their clarification, hopefully using the example or an
> > example.
>
> My point, Topmind, is better answers than the ones you gave exist. If
> you are going to answer these idiots, please give better answers.

I keep asking God to give me superpowers, but he just ignores my calls and sends spammers to my door in white shirts while I'm eating dinner.

-T- Received on Mon Mar 17 2008 - 21:36:54 CET