From: Tom Lane <tgl@sss.pgh.pa.us>
To: =?utf-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <ilmari@ilmari.org>
cc: Matthias van de Meent <boekewurm+postgres@gmail.com>,
        Artur Formella <artur.formella3@gmail.com>,
        pgsql-hackers@postgresql.org
Subject: Re: Allowing additional commas between columns, and at the end of the SELECT clause
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Comments: In-reply-to =?utf-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <ilmari@ilmari.org>
	message dated "Mon, 13 May 2024 13:28:19 +0100"
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Date: Mon, 13 May 2024 10:11:34 -0400
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=?utf-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <ilmari@ilmari.org> writes:
> Matthias van de Meent <boekewurm+postgres@gmail.com> writes:
>> Single trailing commas are a feature that's more and more common in
>> languages, yes, but arbitrary excess commas is new to me. Could you
>> provide some examples of popular languages which have that, as I can't
>> think of any.

> The only one I can think of is Perl, which I'm not sure counts as
> popular any more.  JavaScript allows consecutive commas in array
> literals, but they're not no-ops, they create empty array slots:

I'm fairly down on this idea for SQL, because I think it creates
ambiguity for the ROW() constructor syntax.  That is:

	(x,y) is understood to be shorthand for ROW(x,y)

	(x) is not ROW(x), it's just x

	(x,) means what?

I realize the original proposal intended to restrict the legality of
excess commas to only a couple of places, but to me that just flags
it as a kluge.  ROW(...) ought to work pretty much the same as a
SELECT list.

As already mentioned, if you can get some variant of this through the
SQL standards process, we'll probably adopt it.  But I doubt that we
want to get out front of the committee in this area.

			regards, tom lane