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From: Pei Cao <pc@cs.Princeton.EDU>
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Date: Sat, 6 Aug 1994 18:42:42 -0400
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To: postgres@postgres.Berkeley.EDU
Subject: how is a three-way join implemented?
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Resent-Date: Sat, 06 Aug 94 15:42:52 -0700
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Hi, I am new to Postgres, and would appreciate if anyone can give me some help
on this.

Suppose I have a three way join:

retrive into temp (small.all, large1.all, large2.all) 
where (small.key1 == large1.key1) and (large2.key1 == large1.key1)

where the size of "small" is 1/10 of that of "large1" and "large2".  

Does Postgres join small and large1 first, then join the result relation with 
large2?  Or does it join all three of them together at the same time, if so,
how exactly does it do that?

Thanks a lot!

Pei Cao
CS Dept.
Princeton Universtiy

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