From: Erik Wienhold <ewie@ewie.name>
To: Atomic_Sheep <atomic.sheep@gmail.com>
To: pgsql-docs@lists.postgresql.org
Subject: Re: Cross-Product JOIN?
Date: Wed, 24 May 2023 15:46:28 +0200 (CEST)
Message-ID: <1667253069.131800.1684935988763@office.mailbox.org> (raw)
In-Reply-To: <CAL3CXNMes1r4s78QnMAekj9W1nchGH7dbq86wyEFB2gxqQrJ-g@mail.gmail.com>
References: <CAL3CXNMes1r4s78QnMAekj9W1nchGH7dbq86wyEFB2gxqQrJ-g@mail.gmail.com>
> 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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-docs@postgresql.org
Cc: ewie@ewie.name, atomic.sheep@gmail.com, pgsql-docs@lists.postgresql.org
Subject: Re: Cross-Product JOIN?
In-Reply-To: <1667253069.131800.1684935988763@office.mailbox.org>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox