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From: Tom Lane <[email protected]>
To: Stefan Weiss <[email protected]>
Cc: [email protected]
Subject: Re: INNER JOINS in sql-select.html
Date: Thu, 30 Oct 2003 17:56:04 -0500
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>

Stefan Weiss <[email protected]> writes:
> From <doc/html/sql-select.html>:
> | A CROSS JOIN or INNER JOIN is a simple Cartesian product, the same
> | as you get from listing the two items at the top level of FROM. CROSS
> | JOIN is equivalent to INNER JOIN ON (TRUE), that is, no rows are
> | removed by qualification.

> I thought that by using the second form, you would be able to do
> 'explicit' joins, effectivly telling the planner in which order to
> join multiple tables (in case you have to join 10+ tables)?

They are semantically equivalent, but not necessarily the same from a
performance point of view.  The potential performance issues are covered
elsewhere; I think it would just obfuscate matters to try to include
that topic here.

			regards, tom lane

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