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In-Reply-To: <5e6ae3c1.48b2.19ce5bfea42.Coremail.dingyi_yale@163.com>
From: Fujii Masao <masao.fujii@gmail.com>
Date: Fri, 13 Mar 2026 22:50:07 +0900
Message-ID: 
 <CAHGQGwHGyBAA6e+2eMzOPAbwd9CHKhCCKQ8AVHXG2UwUEj7zew@mail.gmail.com>
Subject: Re: Re: Change COPY ... ON_ERROR ignore to ON_ERROR ignore_row
To: Yi Ding <dingyi_yale@163.com>
Cc: Peter Eisentraut <peter@eisentraut.org>,
 jian he <jian.universality@gmail.com>,
	Matheus Alcantara <matheusssilv97@gmail.com>,
 torikoshia <torikoshia@oss.nttdata.com>,
	Masahiko Sawada <sawada.mshk@gmail.com>, vignesh C <vignesh21@gmail.com>,
	Jim Jones <jim.jones@uni-muenster.de>,
 Kirill Reshke <reshkekirill@gmail.com>,
	Fujii Masao <masao.fujii@oss.nttdata.com>,
	"David G. Johnston" <david.g.johnston@gmail.com>,
 Yugo NAGATA <nagata@sraoss.co.jp>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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On Fri, Mar 13, 2026 at 2:51=E2=80=AFPM Yi Ding <dingyi_yale@163.com> wrote=
:
> The new test added in v1 makes sense to me. A small suggestion is that to=
 verify if a field is really null, we can do:
>
> ALTER FOREIGN TABLE agg_bad OPTIONS (ADD on_error 'set_null');
> SELECT a, b IS NULL FROM agg_bad;

Since the file_fdw test runs "\pset null _null_", a NULL value is displayed=
 as
"_null_". So you can verify that the value is NULL by checking whether
"_null_" is shown.

One could argue that this cannot be distinguished from the literal text val=
ue
"_null_". However, relying on "\pset null _null_" is sufficient for this te=
st,
I think.

Regards,

--=20
Fujii Masao