Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!mintaka!spdcc!merk!uvmark!jim
From: jim@uvmark.uucp (Jim Todhunter)
Newsgroups: comp.databases
Subject: Re: Relational Databases (and why they don't exist)
Message-ID: <1991Jun11.182525.57078@uvmark.uucp>
Date: 11 Jun 91 18:25:25 GMT
References: <1991Jun08.124337.29813@uvmark.uucp> <2421@ccadfa.adfa.oz.au> <25200@oolong.la.locus.com>
Organization: Vmark Software, Inc.
Lines: 58

In article <25200@oolong.la.locus.com> jfr@locus.com (Jon Rosen) writes:
>In article <2421@ccadfa.adfa.oz.au> ghm@ccadfa.adfa.oz.au (Geoff Miller) writes:
>[... much of acrticle deleted ...]
>
>>  However, you can implement a normalised
>>data *model* in ways which use NFNF structures.
>
> This is do NOT understand... If you mean that you can use denormalization
> for performance reasons after having appropriately normalized, I would
> agree... Otherwise, I fail to see how the use of an NFNF model (which
> I agree can be very useful in certain applications) can implement a
> normalized view of the data, since these are essentially contradictory
> views...  Please explain...
> 
> Jon Rosen

The following is an excerpt from e-mail I have been sending to people who
have asked for some references concerning NFNF models.  Although this list
is far from comprehensive, it should serve as a good starting point for
interest parties.  It should also answer the above question.

     There is a growing interest in NFNF database models.  In C.J.Date's
"An Introduction to Database Systems" (vol. I, 5th ed., Addison-Wesley, 1989),
NFNF models are cited as an interesting area for future research.  Date also
references several papers on the subject.

     The activity in this area has been increasing over the years.  Some
relevant papers are:

     Howard M. Dreizen and Shi-Kuo Chang, "Imprecise Schema: A Rationale for
          Relations with Embedded Subrelations", ACM TODS, Vol 14, No. 4, 12/89

     G. Ozsoyoglu, Z. M. Ozsoyogu and V. Matos, "Extending Relational Algebra
          and Relational Calculus with Set-Valued Attributes and Aggregate
          Functions", ACM TODS, Vol. 12, No. 4, 12/87

     Z. Meral Ozsoyogu and Li-Yan Yuan, "A New Normal Form for Nested
          Relations", ACM TODS, Vol. 12, No. 1, 3/87

     Mark A. Roth, Henry F. Korth and Abraham Silberschatz, "Extended Algebra
          and Calculus for Nested Relational Databases", ACM TODS, Vol. 13,
          No. 4, 12/88

     H. J. Schek and M. H. Scholl, "The relational model with relation-valued
          attributes", Information Systems, Vol. 11, No. 2, 1986

     P. Pistor and F. Anderson, "Designing a generalized NF2 model with an
          SQL-type language interface", Proc. 12th Int. Conf. Very Large
          Databases, Kyoto, August 1986

     Note: In this last reference, NF2 is read NF-squared, not second normal
           form.  NF-squared is another name for NFNF.

-- 
 James W. Todhunter, Manager, Software Development
 Vmark Software, Inc., 5 Strathmore Road, Natick, MA  01760, USA
 Internet: uvmark!jim@merk.com, UUCP: uunet!merk!uvmark!jim
 Phone: (508) 655-3700, Fax: (508) 655-8395, Telex: 5101011619 VMARKUNIVERS