Re: Set returning functions in select column list

From: Marti Raudsepp <marti(at)juffo(dot)org>
To: David W Noon <dwnoon(at)ntlworld(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Set returning functions in select column list
Date: 2012-02-17 16:21:07
Message-ID: CABRT9RAMwmvNruvqe4HrvUZUMCMDLhDofjHh50O-w98kjcub7A@mail.gmail.com
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On Fri, Feb 17, 2012 at 17:31, David W Noon <dwnoon(at)ntlworld(dot)com> wrote:
> The words to search for are "Cartesian product".  This is the way
> RDBMSes have handled unconstrained implicit joins since the days of
> SQL/DS.

Yeah, that's what Jack was confused about -- it's actually *not* a
cartesian product. It simply stops enumerating when all the SRFs reach
the end at the same time.

Both of these queries generate 6 rows, although a cartesian product
would mean 12 in the second query:
select generate_series(1,2), generate_series(1,3);
select generate_series(1,2), generate_series(1,6);

Regards,
Marti

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