Re: Object-relational impedence
Date: Mon, 17 Mar 2008 09:12:22 -0700 (PDT)
On Mar 17, 6:44 am, Eric <e..._at_deptj.demon.co.uk> wrote:
> On 2008-03-16, S Perryman <q..._at_q.com> wrote:
> > For the real-world systems involving "variant records" that I have worked
> > on (100+ different record types, 100+ different property types) your table
> > is merely a global variable from hell (as evidenced by the several telecoms
> > systems that used the same approach in the 1990s and ended up being a
> > lifetime rewrite and rebuild job whenever types and properties came and
> > went) .
> If you build a system around something like that, you are crazy. If it
> is a given that you have to deal with, all you can do is treat it as
> messages and parse them to put the information you need into sensible
> structures. This is probably true for a much smaller number of variants.
I suspect his system needed a many-to-many table(s) somewhere, but instead they hardwired many categories into columns and created myriad tables for each (forced) "subtype", like he did in the Publications example from a month or so ago. Perhaps in the 1990's RDMBS performance wasn't good enough to handle many-to-many tables that way. But he still holds a grudge against RDBMS.
-T- Received on Mon Mar 17 2008 - 17:12:22 CET