From: Tom Lane <tgl@sss.pgh.pa.us>
To: Richard Guo <guofenglinux@gmail.com>
cc: Pg Hackers <pgsql-hackers@lists.postgresql.org>,
        "Finnerty,
    Jim" <jfinnert@amazon.com>
Subject: Re: Making Vars outer-join aware
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Comments: In-reply-to Richard Guo <guofenglinux@gmail.com>
	message dated "Tue, 12 Jul 2022 15:20:37 +0800"
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Date: Tue, 12 Jul 2022 09:37:41 -0400
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Richard Guo <guofenglinux@gmail.com> writes:
> Note that the evaluation of expression 'b.j + 1' now occurs below the
> outer join. Is this something we need to be concerned about?

It seems more formally correct to me, but perhaps somebody would
complain about possibly-useless expression evals.  We could likely
re-complicate the logic that inserts PHVs during pullup so that it
looks for Vars it can apply the nullingrels to.  Maybe there's an
opportunity to share code with flatten_join_alias_vars?

			regards, tom lane