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From: miket@blia.BLI.COM (Mike Tossy)
Newsgroups: comp.databases
Subject: Re: Join Contest
Message-ID: <12072@blia.BLI.COM>
Date: 13 Jul 90 21:29:35 GMT
References: <5265@plains.UUCP>
Organization: Britton Lee, Los Gatos, CA
Lines: 27

In article <5265@plains.UUCP>, gus@plains.NoDak.edu 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.
> 
> This seems like an incredible number of joins, especially if the
> tables are large, on the order of 1/2 million tuples.
> 
> Any comment/references, etc.?

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.