Path: utzoo!utgpu!water!watmath!clyde!rutgers!im4u!ut-sally!ut-emx!lad-shrike!chris
From: chris@AUSTIN.LOCKHEED.COM (Chris Wood)
Newsgroups: comp.databases
Subject: Data vs Application oriented design
Summary: Flexibility vs. performance
Keywords: relational,network,comparison
Message-ID: <69@coot.AUSTIN.LOCKHEED.COM>
Date: 7 Jan 88 17:11:12 GMT
References: <12673@pyramid.pyramid.com>
Organization: Lockheed Austin Div.
Lines: 31
Posted: Thu Jan  7 11:11:12 1988

In article <12673@pyramid.pyramid.com>, eric@pyrps5 (Eric Bergan) writes:
> 	Have all the applications that you have worked on been static
> entities, that didn't change as you after you had initially designed the
> database?  If a network database-based application suddenly needs to
> support a new query that it was not initially designed for (but has the
> data for), a significant redesign may be necessary. In a properly designed
> relational database, the data independence allows you to avoid this
> redesign.
> 

I submit that the above is true because Relational systems are designed
to fit the data, whereas network systems are/were typically designed to
fit the applications.  This means that network systems were very concerned
with performance issues to meet the response time needs of specific
applications.  It is entirely possible to build a CODASYL database design
that does not use the dreaded "imbedded pointers" and is just a set of 
(dare I say it) relations that are unrelated.  True, now you have lost much
of the power of the DBMS, but look how easy it is to reorganize!

Heretical statement follows:

Thus it follows that the Relational model is a SUBSET of the network model.

OOOOOOOOOOhhhhhhh  boy, that ought to generate some flames!

Chris Wood

By the way, keep in mind that I am playing Devil's advocate here.  I have 
used many DBMS's over the years, but now I am using only Relational ones.
(When was the last time a major vendor announced a NEW DBMS product that
wasn't relational?)