Path: utzoo!mnetor!uunet!mcvax!cernvax!ethz!marti
From: marti@ethz.UUCP (Robert Marti)
Newsgroups: comp.databases
Subject: Re: Database implementation/theory issues?  (Semantic Data Models)
Message-ID: <311@bernina.UUCP>
Date: 2 Mar 88 13:27:22 GMT
References: <33671UH2@PSUVM> <232@cullsj.UUCP> <725@smidefix.liu.se>
Organization: ETH Zuerich, Switzerland
Lines: 38
Summary: 1. It ain't easy to implement.   2. There was no market.

In article <725@smidefix.liu.se>, gorry@smidefix.liu.se (Goran Rydquist) writes:
> The greatest evil in today database theory is the unquestioned (?) assumption
> that the data model must be based on records.  [ ... ]
> 
> I quote:
> 	[ ... Quote ... ]
> [W. Kent, Limitations of Record-Based Information Models", ACM Transactions on
> Database Systems, vol 4, no 1, pp 107-131, March 1979]
> 
> I would like to hear comments, historical motivations, views etc.
> 
> Goran Rydqvist			gorry@majestix.liu.se
> ---------

The ideas contained in Bill Kent's paper are now more than 10 years
old.  Even today, however, there are not many systems which implement
them.  This is partly due to the fact that their implementation has
turned out to be decidedly non-trivial:  Apart from deciding on how
to map the data model onto secondary storage you also have to consider
access path, recovery, and concurrency control issues.

A few systems have been built as research prototypes -- CCA's work on
DAPLEX (LDM, DDM), Xerox PARC's Cypress, and the TAXIS project at U
Toronto come to mind.  But there are certainly no widely used products
which support semantic data models on the market today, although the
situation seems to be changing with all the interest in applying database
techniques to engineering and AI applications:  A new generation of
object-oriented database systems is emerging, e.g., Servio Logic's
GemStone and Ontologic's VBase products.

Still, users of record-oriented database systems apparently have been
able to build a lot of very useful applications with this technology.

-- 
Robert Marti                    Phone:       +41 1 256 52 36
Institut fur Informatik
ETH Zentrum/SOT                 CSNET/ARPA:  marti%ifi.ethz.ch@relay.cs.net
CH-8092 Zurich, Switzerland     UUCP:        ...uunet!mcvax!ethz!marti