Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uwm.edu!bionet!apple!sun-barr!newstop!texsun!texbell!uudell!loft386!wes
From: wes@loft386.uucp (Wes Peters)
Newsgroups: comp.databases
Subject: Re: Join Contest
Summary: Join 10-15 tables in a single query?  Not in my world!
Message-ID: <1990Jul27.042508.10645@loft386.uucp>
Date: 27 Jul 90 04:25:08 GMT
References: <5265@plains.UUCP>
Organization: Lofty Pursuits Public Access Unix for Rapid City, SD USA
Lines: 18

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.?

My company has an application for tracking software problems and
changes that runs on Oracle.  Last week, I tried running a selection
that joined 3 tables*.  On our system, a cluster of 3 VAX 8250s
running VMS 4.7 and Oracle 5.1.22, this selection would not produce
any output in 45 minutes.  Dropping one table from the selection
resulted in output typically in 30-40 seconds.

*Actually we were selecting from 3 public synonyms for tables "owned"
by another Oracle user.  I'm sure our selection was pretty pessimal in
it's order of query, but still 45 minutes?  Yuck!