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From: garyp@cognos.uucp (Gary Puckering)
Newsgroups: comp.databases
Subject: Re: Relational vs. Network Model Performance
Message-ID: <521@cognos.uucp>
Date: Tue, 7-Apr-87 00:23:52 EST
Article-I.D.: cognos.521
Posted: Tue Apr  7 00:23:52 1987
Date-Received: Sat, 11-Apr-87 00:50:52 EST
References: <1361@hou2d.UUCP>
Reply-To: garyp@cognos.UUCP (Gary Puckering)
Organization: Cognos Incorporated, Ottawa, Canada
Lines: 35

In article <1361@hou2d.UUCP> sachar@hou2d.UUCP writes:
>Ignoring the user friendly and other issues, network model bases
>databases should have better performance than relational model
>based databases due to presence of links. 

This is a commonly-held fallacy.  Linkage paths represent an
implementation option, just as B-tree, hash and clustered indexes are
options that speed up certain queries.  There is no theoretical reason
why a network dbms should perform better than a relational dbms.  Only
practical reasons.  Most of the systems I've measured tend to perform
somewhat below their network counterparts because:

1)  They do a lot more (there's more code, etc.)

2)  They provide greater data independance (datatype conversions)

3)  They provide more sophisticated locking and transaction management
    (degree 3 consistency, as opposed to degree 2)

4)  They provide varying-length datatypes and null-values, which means
    more overhead in terms of a record management scheme

5)  They are immature products

The last point is perhaps the most important to bear in mind.
Commercial relational systems are still immature in comparison to most
network and hierarchical dbms's.  Ask someone who was involved when
IBM's IMS was introduced.  Comparing DB2 performance to IMS performance
is like comparing an 8-year old runner to a 20-year old runner.  In a
few years I thin the performance debate will fade away.

-- 
Gary Puckering        3755 Riverside Dr.
Cognos Incorporated   Ottawa, Ontario       decvax!utzoo!dciem!
(613) 738-1440        CANADA  K1G 3N3       nrcaer!cognos!garyp