Re: vehicle to autoparts relationships

NENASHI, Tegiri wrote:
> "Aloha Kakuikanu" <aloha.kakuikanu_at_yahoo.com> wrote in
> news:1164226982.397468.272020_at_b28g2000cwb.googlegroups.com:
>
>
> > Contrary to what object people may say that assembling and
> > disassembling things within a computer environment is not a big deal.
> > It is certainly not a reason to dismiss relational approach.
> >
> > Now, there are some larger parts, ggregated from the smaller ones, for
> > example, trigger assembly, or stock. How do we handle these? Simple,
> > they are just sets:
> >
> > table AssemblyParts (
> > assemblyPartNo integer, // informally it is a set#
> > partNo integer, // foreign key to Parts
> > );
> >
> > Granted, some of the interested queries become set joins, so you have
> > to be familiar with the concept of set join. Other than that I don't
> > see any problems. Do you?
>
> You want to say the set containment join, is not it ? If you do, there
> are two problems: 1) the performance of set containment join; 2) the set
> valued attribute, or relation valued attribute, is not realised by all
> the databases. One can have a separate relation in the place of the
> relation valued attribute, of course, but then how does one reference the
> relation from AssemblyParts with assemblyPartNo ?

No nested relations. Can't one express set containment join in plain SQL the same way one writes relational division query? Next, how many parts a typical vehicle has, pehaps 1000? Wouldn't relational division kind of query perform OK on such relatively small dataset (no matter how bad the execution plan is)? Received on Thu Nov 23 2006 - 02:13:37 CET