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From: chiu@brahms.amd.com (Timothy Chiu)
Newsgroups: comp.databases
Subject: Re: Join Contest
Message-ID: <1990Jul17.182426.25684@amd.com>
Date: 17 Jul 90 18:24:26 GMT
References: <5314@plains.UUCP>
Sender: usenet@amd.com (NNTP Posting)
Organization: Advanced Micro Devices; Sunnyvale, CA
Lines: 34

In article <5314@plains.UUCP> gus@plains.UUCP (jim gustafson) writes:
>In article <933@dgis.dtic.dla.mil> jkrueger@dgis.dtic.dla.mil (Jon) writes:
>
>>>Recently I heard that an IBM-type db person claimed that it's
>>>not uncommon in commercial db applications to join as many as
>>>10-15 (maybe even 30) tables in a single query.
> 
>>It is uncommon.  Ask your IBM-type db person to substantiate
>>his claim.  "Extraordinary claims require extraordinary
>>justification".  In fact it's difficult to design a query that
>>makes sense with more than about five joins.  Try it.
> 
>>-- Jon
>>-- 
>>Jonathan Krueger    jkrueger@dtic.dla.mil   uunet!dgis!jkrueger
>>Drop in next time you're in the tri-planet area!
>

Well, let's see, I used to work for a major money center bank on
Wall Street and we used DB2, (IBM's hideous monster) and the 
applications I worked with used joins of up to 18 different 
tables (each table represented a different business activity
of the bank, but contained information from more than one 
subsidiary).  To find information about one subsidiary it was
not uncommon to have huge table joins, this added to the fact
we had truly "brain-dead" users made for some interesting QMF
problems.  If anyone's truly interested I can send them more
details via e-mail.

--
Timothy Z. Chiu      | -- This space under construction --  
chiu@brahms.amd.com  |
Advanced Micro Devices, M/S 167 P.O. Box 3453, Sunnyvale, CA 94088-3000
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