Path: utzoo!attcan!uunet!ogicse!plains!gus
From: gus@plains.UUCP (jim gustafson)
Newsgroups: comp.databases
Subject: Re: Join Contest
Message-ID: <5314@plains.UUCP>
Date: 17 Jul 90 08:05:58 GMT
Organization: North Dakota State University  Fargo, ND
Lines: 47

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!


Jon, in case you missed it, I'll repost what I guess would be 
a main contender and an example of an "uncommon" join.  I have 
seen/heard of several other examples of "monster" joins, but I 
am still interested in hearing from anyone who works with large, 
m-way joins.

Thanks,
Jim Gustafson	gus@plains.nodak.edu	
uunet!plains!gus (UUCP)	gus@plains (Bitnet)


+------------------- mike's --------- mail -------------------
| We have an instalation in the U.S. Navy (a personnel application) that
| routinely runs 15 way joins.  They were very pleased when we increased
| the limit with ShareBase II (from 16 tables under ShareBase I).
| 
| My observation is that the number of tables used by an application 
| increases dramaticly if the database design is well normalized.
| 
| --
|						  Teradata Corporation
| Mike Tossy                                      ShareBase Division
| miket@blia.bli.com                              14600 Wichester Blvd
| (408) 378-7575 ext2200                          Los Gatos, CA 95030
|					(Formerly: Britton Lee, Inc.)
| 
| These are only my opinions.
-- 
Jim Gustafson	gus@plains.nodak.edu	
uunet!plains!gus (UUCP)	gus@plains (Bitnet)