Date: Wed, 24 May 2023 15:46:28 +0200 (CEST)
From: Erik Wienhold <ewie@ewie.name>
To: Atomic_Sheep <atomic.sheep@gmail.com>, pgsql-docs@lists.postgresql.org
Message-ID: <1667253069.131800.1684935988763@office.mailbox.org>
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 <CAL3CXNMes1r4s78QnMAekj9W1nchGH7dbq86wyEFB2gxqQrJ-g@mail.gmail.com>
References: 
 <CAL3CXNMes1r4s78QnMAekj9W1nchGH7dbq86wyEFB2gxqQrJ-g@mail.gmail.com>
Subject: Re: Cross-Product JOIN?
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> On 24/05/2023 10:22 CEST Atomic_Sheep <atomic.sheep@gmail.com> wrote:
>
> "Finally, NATURAL is a shorthand form of USING: it forms a USING list
> consisting of all column
> names that appear in both input tables. As with USING, these columns
> appear only once in the
> output table. If there are no common column names, NATURAL JOIN
> behaves like JOIN ...
> ON TRUE, producing a cross-product join."
>
> Did it mean cartesian product and not cross-product?

Cross product means cartesian product in this context.  So technically correct.
Personally, I think it should read cartesian product because cross product is an
overloaded term and cartesian product is used more often in the documentation
overall.

But the same page [0] also uses cross product when talking about grouping sets.

The source code uses cross product in a couple of comments, though.

[0] https://www.postgresql.org/docs/15/queries-table-expressions.html

--
Erik