MIME-Version: 1.0
From: SATYANARAYANA NARLAPURAM <satyanarlapuram@gmail.com>
Date: Mon, 13 Apr 2026 02:21:28 -0700
Message-ID: 
 <CAHg+QDcfpGDoPL3fvfjXRtfn=fny6DdJR6BAy6TpS1Xj2EZfXA@mail.gmail.com>
Subject: Bug: COPY FORMAT JSON includes generated columns unlike text/CSV
To: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
	Richard Guo <guofenglinux@gmail.com>
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Hi hackers,

COPY TO with FORMAT json includes generated columns in the output,
while text and CSV formats correctly exclude them.  Virtual generated
columns appear as null (since they aren't materialized), and stored
generated columns appear with their values  Attached a patch to address
this.

Repro:

    CREATE TABLE t (id int, a int,
        s int GENERATED ALWAYS AS (a * 10) STORED,
        v int GENERATED ALWAYS AS (a * 100) VIRTUAL);
    INSERT INTO t (id, a) VALUES (1, 5);

    COPY t TO STDOUT;
    COPY t TO STDOUT WITH (FORMAT csv, HEADER);
    COPY t TO STDOUT WITH (FORMAT json);
CREATE TABLE
INSERT 0 1
1       5
id,a
1,5
{"id":1,"a":5,"s":50,"v":null}

After the fix:
COPY t TO STDOUT WITH (FORMAT json);
{"id":1,"a":5}

Thanks,
Satya

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<div dir=3D"ltr">Hi hackers,<div><br>COPY TO with FORMAT json includes gene=
rated columns in the output,<br>while text and CSV formats correctly exclud=
e them.=C2=A0 Virtual generated<br>columns appear as null (since they aren&=
#39;t materialized), and stored<br>generated columns appear with their valu=
es=C2=A0 Attached a patch to address this.</div><div><br></div><div>Repro:<=
br><br>=C2=A0 =C2=A0 CREATE TABLE t (id int, a int,<br>=C2=A0 =C2=A0 =C2=A0=
 =C2=A0 s int GENERATED ALWAYS AS (a * 10) STORED,<br>=C2=A0 =C2=A0 =C2=A0 =
=C2=A0 v int GENERATED ALWAYS AS (a * 100) VIRTUAL);<br>=C2=A0 =C2=A0 INSER=
T INTO t (id, a) VALUES (1, 5);</div><div><br></div><div>=C2=A0 =C2=A0 COPY=
 t TO STDOUT;<br>=C2=A0 =C2=A0 COPY t TO STDOUT WITH (FORMAT csv, HEADER);<=
br>=C2=A0 =C2=A0 COPY t TO STDOUT WITH (FORMAT json);<br>CREATE TABLE<br>IN=
SERT 0 1<br>1 =C2=A0 =C2=A0 =C2=A0 5<br>id,a<br>1,5</div><div>{&quot;id&quo=
t;:1,&quot;a&quot;:5,&quot;s&quot;:50,&quot;v&quot;:null}=C2=A0</div><div><=
br></div><div>After the fix:</div><div>COPY t TO STDOUT WITH (FORMAT json);=
<br>{&quot;id&quot;:1,&quot;a&quot;:5}=C2=A0<br><br>Thanks,</div><div>Satya=
</div></div>

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