From: Tom Lane <tgl@sss.pgh.pa.us>
To: Richard Guo <guofenglinux@gmail.com>
cc: Etsuro Fujita <etsuro.fujita@gmail.com>,
        Alexander Pyhalov <a.pyhalov@postgrespro.ru>,
        PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Subject: Re: foreign join error "variable not found in subplan target list"
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Comments: In-reply-to Richard Guo <guofenglinux@gmail.com>
	message dated "Tue, 30 Aug 2022 09:18:54 +0800"
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Date: Mon, 29 Aug 2022 22:04:39 -0400
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Richard Guo <guofenglinux@gmail.com> writes:
> To be concrete, I mean something like this:

> +               /* Update the cost and width fields if we have added any
> new columns. */
> +               if (!equal(epq_path->pathtarget->exprs, target->exprs))
> +                       set_pathtarget_cost_width(root, target);

Wouldn't a list_length() comparison be sufficient?  equal() seems
like overkill.

			regards, tom lane