MIME-Version: 1.0
References: <19463-f59d5d2a41969756@postgresql.org>
In-Reply-To: <19463-f59d5d2a41969756@postgresql.org>
From: surya poondla <suryapoondla4@gmail.com>
Date: Mon, 27 Apr 2026 15:31:27 -0700
Message-ID: <CAOVWO5pvxWGTr_YTFd6=kvCLk_4Jpaj13gNBY=NJZ9BTh+ounw@mail.gmail.com>
Subject: Re: BUG #19463: Server crash (Assertion failure) when using MERGE
 statement in CTE
To: 303677365@qq.com, pgsql-bugs@lists.postgresql.org
Content-Type: multipart/alternative; boundary="000000000000a53e8d065078ad81"
Archived-At: <https://www.postgresql.org/message-id/CAOVWO5pvxWGTr_YTFd6%3DkvCLk_4Jpaj13gNBY%3DNJZ9BTh%2Bounw%40mail.gmail.com>
Precedence: bulk

--000000000000a53e8d065078ad81
Content-Type: text/plain; charset="UTF-8"

Hi Chunling,

Thank you for reporting the issue.

I tried to reproduce the issue on postgres19 and I don't see any crash.

psql (19devel)
Type "help" for help.

postgres=#
postgres=#
postgres=#
postgres=# CREATE TABLE target (col_int INT, col_varchar VARCHAR(2000));
CREATE TABLE
postgres=# CREATE TABLE source (col_int INT, col_varchar VARCHAR(2000));
CREATE TABLE
postgres=# INSERT INTO source VALUES (1, 'test');
INSERT 0 1
postgres=#
postgres=#
postgres=# WITH merge_cte AS (
postgres(#     MERGE INTO target t
postgres(#     USING source s ON t.col_int = s.col_int
postgres(#     WHEN NOT MATCHED THEN INSERT (col_int, col_varchar) VALUES
 WHEN NOT MATCHED THEN INSERT (col_int, col_varchar) VALUES (s.col_int,
postgres(# s.col_varchar)
postgres(# )
postgres-# SELECT col_int FROM merge_cte;
ERROR:  WITH query "merge_cte" does not have a RETURNING clause
LINE 7: SELECT col_int FROM merge_cte;
                            ^
postgres=# WITH merge_cte AS (
postgres(# MERGE INTO target t
postgres(# USING source s ON t.col_int = s.col_int
postgres(# WHEN NOT MATCHED THEN INSERT (col_int, col_varchar) VALUES
(s.col_int, s.col_varchar) RETURNING t.col_int
postgres(# )
postgres-# SELECT col_int FROM merge_cte;
 col_int
---------
       1
(1 row)

I tried to reproduce the issue on postgres15 too, but i see ERROR:  MERGE
not supported in WITH query.


Regards,
Surya Poondla

--000000000000a53e8d065078ad81
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div dir=3D"ltr">Hi Chunling,<br><br>Thank you for reporti=
ng the issue.<br><br>I tried to reproduce the issue on postgres19 and I don=
&#39;t see any crash.<br><br>psql (19devel)<br>Type &quot;help&quot; for he=
lp.<br><br>postgres=3D# <br>postgres=3D# <br>postgres=3D# <br>postgres=3D# =
CREATE TABLE target (col_int INT, col_varchar VARCHAR(2000));<br>CREATE TAB=
LE<br>postgres=3D# CREATE TABLE source (col_int INT, col_varchar VARCHAR(20=
00));<br>CREATE TABLE<br>postgres=3D# INSERT INTO source VALUES (1, &#39;te=
st&#39;);<br>INSERT 0 1<br>postgres=3D# <br>postgres=3D# <br>postgres=3D# W=
ITH merge_cte AS (<br>postgres(# =C2=A0 =C2=A0 MERGE INTO target t<br>postg=
res(# =C2=A0 =C2=A0 USING source s ON t.col_int =3D s.col_int<br>postgres(#=
 =C2=A0 =C2=A0 WHEN NOT MATCHED THEN INSERT (col_int, col_varchar) VALUES =
=C2=A0 =C2=A0WHEN NOT MATCHED THEN INSERT (col_int, col_varchar) VALUES (s.=
col_int,<br>postgres(# s.col_varchar)<br>postgres(# )<br>postgres-# SELECT =
col_int FROM merge_cte;<br>ERROR: =C2=A0WITH query &quot;merge_cte&quot; do=
es not have a RETURNING clause<br>LINE 7: SELECT col_int FROM merge_cte;<br=
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 ^<br>postgres=3D# WITH merge_cte AS (<br>postgres(=
# MERGE INTO target t<br>postgres(# USING source s ON t.col_int =3D s.col_i=
nt=C2=A0<br>postgres(# WHEN NOT MATCHED THEN INSERT (col_int, col_varchar) =
VALUES (s.col_int, s.col_varchar) RETURNING t.col_int<br>postgres(# )<br>po=
stgres-# SELECT col_int FROM merge_cte;<br>=C2=A0col_int <br>---------<br>=
=C2=A0 =C2=A0 =C2=A0 =C2=A01<br>(1 row)<br><br>I tried to reproduce the iss=
ue on postgres15 too, but i see=C2=A0ERROR: =C2=A0MERGE not supported in WI=
TH query.<br><br><br>Regards,<br>Surya Poondla</div></div>

--000000000000a53e8d065078ad81--