From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andrew Gierth <andrew@tao11.riddles.org.uk>
cc: Michael Paquier <michael@paquier.xyz>, cyg0810@gmail.com,
        pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17088: FailedAssertion in prepagg.c
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References: <17088-e33882b387de7f5c@postgresql.org>
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Comments: In-reply-to Andrew Gierth <andrew@tao11.riddles.org.uk>
	message dated "Wed, 07 Jul 2021 22:18:01 +0100"
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Date: Wed, 07 Jul 2021 17:22:17 -0400
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Andrew Gierth <andrew@tao11.riddles.org.uk> writes:
> A number of places in the planner have to explicitly avoid recursing
> into GroupingFunc->args when walking trees specifically because they are
> not evaluated. It looks to me like some places where that should have
> been checked for were missed. Looking into it.

Hmm.  Maybe it'd be better if the default behavior in
expression_tree_walker/mutator did not include recursing into the args,
then?  I am thinking this might be comparable to SubLinks/SubPlans, where
the walker has to take explicit action if it wants to recurse into the
sub-query.

			regards, tom lane