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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Bruce Momjian <bruce@momjian.us>
cc: "David G. Johnston" <david.g.johnston@gmail.com>,
        Laurenz Albe <laurenz.albe@cybertec.at>, postgres-hape@gmx.de,
        pgsql-docs@lists.postgresql.org
Subject: Re: group by can use alias from select list
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Comments: In-reply-to Bruce Momjian <bruce@momjian.us>
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Bruce Momjian <bruce@momjian.us> writes:
> On Tue, Jul 11, 2023 at 07:31:26AM -0700, David G. Johnston wrote:
>> I think the complaint is that someone seeing the behavior in the wild c=
omes to
>> this order-of-operations and doesn't see that the observed behavior is
>> documented.

> How is the attached patch?

Maybe better "Although query output columns are nominally computed in the
next step, they can also be referenced (by name or by ordinal number)
as <literal>GROUP BY</literal> elements".

You could go further and add "Such references cannot be parts of
<literal>GROUP BY</literal> expressions, however."  Not sure if we
cover that explicitly anywhere else.

			regards, tom lane