Re: Object-relational impedence
Date: Thu, 6 Mar 2008 18:19:33 +0100 (CET)
Message-ID: <Xns9A597D7B1BA4Evdghher_at_194.177.96.26>
S Perryman <q_at_q.com> wrote in news:fqp6ip$bje$1_at_aioe.org:
>> Does "the semantics of "joins" are an issue for OO" mean that >> relational joins cannot be implemented in principle in an >> object-oriented way ?
>
> IMHO most things can be implemented in principle.
> Efficiency etc is another (important) matter.
>
> Thinking out loud ...
>
> My unease about joins is that in the ADT/OO sense, for your example
> etc we effectively create instances of a new type whose properties
> actually belong to multiple (existing) object instances. Properties
> that may be realised as computational operations.
>
> I feel that prevailing impls of OO are not up to the job of doing the
> above (although having a consistent Relational infrastructure that
> apart from joins - works is and is programmed the same way for both
> ADT-based and "data value only" types/tuples - is something I have
> long wanted) .
That was refreshingly honest ! Thank you.
However, without joins what is left of the RM ? I think that even projections are not very palatable to the OO model. If so, that leaves us with something not very useful for data management at all.
>
> I similarly feel that Functional programming may have the answers to
> the problems (the execution engines in particular) .
There are some ( http://www.csd.abdn.ac.uk/ ~pgray/graduate_course2004/monad.pdf ) but they have a bunch of their own issues, mainly related to join performance (not surprisingly). But, I agree, FP way may still bear some relational fruits as opposed to the barren OOP tree ;)
>
> But thinking out loud and "feeling" is hardly knowing (one way or the
> other) is it. :-( :-)
>
>
> Regards,
> Steven Perryman
>
Received on Thu Mar 06 2008 - 18:19:33 CET