From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: xinwen@stu.scu.edu.cn, pgsql-bugs@lists.postgresql.org,
        David Rowley <dgrowleyml@gmail.com>
Subject: Re: BUG #17777: An assert failed in nodeWindowAgg.c
In-reply-to: <20230211004940.t5l2dz7rnss76zao@awork3.anarazel.de>
References: <17777-860b739b6efde977@postgresql.org>
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Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Fri, 10 Feb 2023 16:49:40 -0800"
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Date: Fri, 10 Feb 2023 20:08:09 -0500
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Andres Freund <andres@anarazel.de> writes:
> I think we could just add a !contain_subplans() to the code deciding whether
> it's safe to use the movable window optimization?

Yeah, perhaps.  That doesn't seem like a mainstream use-case either.

Another idea, tying into your previous point, is to try to check
contain_volatile_functions in the planner before we've reduced
sublinks to subplans.  I'm not sure that would be convenient to do
though; subplan-conversion happens pretty early.

(I'm quite hesitant to move the goalposts on what
contain_volatile_functions detects.  As that comment indicates,
some thought has gone into its current behavior, and I think
we might hit some unwanted side-effects if we change it.)

			regards, tom lane