From: Tom Lane <tgl@sss.pgh.pa.us>
To: Richard Guo <guofenglinux@gmail.com>
cc: David Rowley <dgrowleyml@gmail.com>,
        Dean Rasheed <dean.a.rasheed@gmail.com>,
        Ronan Dunklau <ronan.dunklau@aiven.io>,
        Justin Pryzby <pryzby@telsasoft.com>,
        Pavel Luzanov <p.luzanov@postgrespro.ru>,
        pgsql-hackers@lists.postgresql.org,
        Ranier Vilela <ranier.vf@gmail.com>
Subject: Re: Add proper planner support for ORDER BY / DISTINCT aggregates
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Comments: In-reply-to Richard Guo <guofenglinux@gmail.com>
	message dated "Tue, 17 Jan 2023 14:29:56 +0800"
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Date: Tue, 17 Jan 2023 02:05:19 -0500
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Richard Guo <guofenglinux@gmail.com> writes:
> BTW, I wonder if we should have checked CoercionForm before
> fix_upper_expr_mutator steps into CoerceViaIO->arg to adjust the expr
> there.

I will just quote what it says in primnodes.h:

 * NB: equal() ignores CoercionForm fields, therefore this *must* not carry
 * any semantically significant information.

If you think the planner should act differently for different values of
CoercionForm, you are mistaken.  Maybe this is evidence of some
previous bit of brain-fade, but if so we need to fix that.

			regards, tom lane