From: Tom Lane <tgl@sss.pgh.pa.us>
To: jian he <jian.universality@gmail.com>
cc: "David G. Johnston" <david.g.johnston@gmail.com>,
        PetSerAl <petseral@gmail.com>,
        "pgsql-bugs@lists.postgresql.org" <pgsql-bugs@lists.postgresql.org>
Subject: Re: Record returning function accept not matched columns declaration
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Comments: In-reply-to jian he <jian.universality@gmail.com>
	message dated "Mon, 04 Mar 2024 08:00:00 +0800"
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Date: Sun, 03 Mar 2024 19:40:01 -0500
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jian he <jian.universality@gmail.com> writes:
> On Sat, Mar 2, 2024 at 1:56 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I'm having mixed feelings about whether to back-patch this.  Somebody
>> might complain that we broke a working query in a minor release.

> context: in postgres 9.3.25, dbfiddle[1]
> this query will fail:

> with a(b) as (values (row(1,2,3)))
> select * from a, coalesce(b) as c(d int, e int);

Sure, but in v12 and up (i.e., the supported versions that we might
back-patch into) the query succeeds, and it might not be obvious
to someone that its behavior isn't as-intended.

Admittedly, this seems like a rather contrived case.  In cases
where the record-returning function call isn't reducible to a
constant, you'll get the expected error.  So maybe I'm worrying
over something that no one is depending on in practice.

> I think by ExecMakeTableFunctionResult you mean `mainly
> ExecMakeTableFunctionResult's function: tupledesc_match`
> since ExecMakeTableFunctionResult is quite long.

Perhaps.  I mentioned ExecMakeTableFunctionResult because that's
what's called directly from nodeFunctionscan.c.  Referencing a
static function of another module is risky because it's pretty
unlikely the comment would get updated if refactoring in that
module makes it false.

			regards, tom lane