From: Tom Lane <tgl@sss.pgh.pa.us>
To: Amit Langote <amitlangote09@gmail.com>
cc: fedor_erastov@mail.ru,
        PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>,
        Andres Freund <andres@anarazel.de>,
        Andrew Dunstan <andrew@dunslane.net>
Subject: Re: BUG #16644: null value for defaults in OLD variable for trigger
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References: <16644-5da7ef98a7ac4545@postgresql.org>
 <802555.1601432494@sss.pgh.pa.us>
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 <207142.1603468329@sss.pgh.pa.us> <568704.1603648770@sss.pgh.pa.us>
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Comments: In-reply-to Amit Langote <amitlangote09@gmail.com>
	message dated "Mon, 26 Oct 2020 12:11:23 +0900"
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Date: Sun, 25 Oct 2020 23:19:04 -0400
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Amit Langote <amitlangote09@gmail.com> writes:
> On Mon, Oct 26, 2020 at 5:53 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Moreover, it's more correct, even disregarding the problem
>> at hand, because the tlist isn't a perfectly accurate depiction of
>> the relation rowtype: ExecCleanTypeFromTL will not derive the correct
>> info for dropped columns.

> Hmm, I don't understand.  Isn't it the planner's job to make the
> targetlist correctly account for dropped columns; what
> expand_targetlist() does?

Yes, there are columns in the tlist to match them, but ExecCleanTypeFromTL
cannot mark those columns as "attisdropped".  The column data type
likely won't be right either.  The latter shouldn't matter, if the
column is being filled with a null ... but I'm a bit surprised that
we've gotten away this long with not being honest about attisdropped.

			regards, tom lane