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From: agonzale@nmsu.edu (Agustin Gonzalez-Tuchmann)
Newsgroups: comp.databases
Subject: Re: Database Comparisons
Message-ID: <580@opus.NMSU.Edu>
Date: 7 Feb 91 22:25:00 GMT
References: <10737@pasteur.Berkeley.EDU>
	<1991Feb7.134634.26917@infonode.ingr.com> <10876@pasteur.Berkeley.EDU>
	<1991Feb7.190050.449@inel.gov>
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In-reply-to: cdm@gem-hy.Inel.GOV's message of 7 Feb 91 19:00:50 GMT

In article <1991Feb7.190050.449@inel.gov> cdm@gem-hy.Inel.GOV (Dale Cook) writes:

   In article <10876@pasteur.Berkeley.EDU>, mao@eden.Berkeley.EDU (Mike
   Olson) writes:
   |> In <1991Feb7.134634.26917@infonode.ingr.com>, tensmekl@infonode.ingr.com
   |> (Kermit Tensmeyer) writes
   |> 
   |> > Personnally, I don't see that much need to real relational databases. Most
   |> > of the applications that I see in the real world use the database as
   |> > complicated ISAM files. Network Databases seemed to use the resources more
   |> > efficently.
   |> 
   |> > I suspect that the idea of Relational Data format is more sexier to
   managers
   |> > than the other types of databases.  Is there any real world advantage to
   |> > RDBMS?
   |> 
   |> if your application is cast in concrete, it may be better to write a
   |> special-purpose data manager.  flight reservations is an example of an
   |> application area that's been pretty successful at doing non-relational
   |> data management commercially.
   |> 
   |> however, there are several drawbacks:
   |> 
   |> 	+  NO ad-hoc queries.  if you want to get some data out of the
   |> 	   database, you have to understand its structure and write a
   |> 	   program.
   |> 

   Excuse me, but this has nothing to do with RDBMS format.  I've worked with a
   non-relational DBMS system that has adhoc query capability, you don't have
   to understand the structure any more than you do an RDBMS.  The particular
   DBMS I refer to is ADABAS, and I would wager there are others.

There has to be an underlying model, though. In hard-coded application
the files and application programs very often result in different
solutions to common problems. This makes it difficult to create an
ad-hoc query program.


   |> 	+  you're not insulated from changes in the the storage structure.
   |> 	   if i change the way that records are organized on the disk (a
   |> 	   thing that i might do, for example, to speed up certain types
   |> 	   of searches) you have to rewrite all the computer programs that
   |> 	   use the database.
   |>

   Nonsense.

If you use a relational data base manager you can achieve data
independance with less pain than in normal procedural languages.

   |> 	+  as a corollary to the last point, there's no simple way for you
   |> 	   to speed up a query short of recoding the program that implements
   |> 	   it.  on a relational system, i can just define an index and let
   |> 	   the optimizer do the right thing.
   |>

   Again, nonsense.

I don't see how you can speed up a query without rewriting the
program. Thus it makes sense to me.


   |> in general, query optimizers have proven to be about as good as competent
   |> programmers in picking the right query.  a programmer with extra information
   |> about the data on the disk can sometimes do better than an optimizer, but
   |> the additional cost of programming every query by hand has to be considered
   |> as well.  finally, all the commercial people are claiming that we're on
   |> our way to twenty-way joins.  i don't really believe that, but if it's
   |> true, then the programmer does not exist who can hand-optimize the query
   |> in finite time.
   |> 
   |> in short, relational systems have a substantial advantage over network and
   |> hierarchical database systems for common business applications that involve
   |> ad-hoc queries and frequent schema changes.
   |> 

   That may be true, but you haven't given us any real examples why.

   The biggest advantage I have seen is that they enforce somewhat more rigor
   in your data design, e.g., you can't have repeating groups.


I think the biggest advantages is having a data model ( it enforces
rigor on design, if that's what you want), data independance, and
I think the most important -and often most overlooked feature--
it gives non-programmers a big chance to ask questions through
the query manager of the rdbm (or dbm).


--
Agustin Gonzalez-Tuchmann                    dbase-l list owner.
New Mexico State University                  Office: SH-165
Computer Science Department                  Phone: (505) 646-6243
Las Cruces, N.M. 88003-0001                  e-mail: agonzale@nmsu.edu