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help / color / mirror / Atom feedFrom: jian he <[email protected]>
To: SATYANARAYANA NARLAPURAM <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: Richard Guo <[email protected]>
Subject: Re: Bug: COPY FORMAT JSON includes generated columns unlike text/CSV
Date: Tue, 14 Apr 2026 22:46:56 +0800
Message-ID: <CACJufxEDsyWG0-k_yQszrDw9DpOU0Rvti6EJu5kmQ26HEbHQSw@mail.gmail.com> (raw)
In-Reply-To: <CAHg+QDcfpGDoPL3fvfjXRtfn=fny6DdJR6BAy6TpS1Xj2EZfXA@mail.gmail.com>
References: <CAHg+QDcfpGDoPL3fvfjXRtfn=fny6DdJR6BAy6TpS1Xj2EZfXA@mail.gmail.com>
On Mon, Apr 13, 2026 at 5:21 PM SATYANARAYANA NARLAPURAM
<[email protected]> wrote:
>
> 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.
>
The patch looks good to me.
It seems there's a ``git apply`` issue applying the V1 patch.
The attached v2 is the same as your v1, it should apply without issue
using `git apply` or `git am`.
--
jian
https://www.enterprisedb.com/
Attachments:
[text/x-patch] v2-0001-COPY-FORMAT-JSON-with-generated.patch (3.5K, 2-v2-0001-COPY-FORMAT-JSON-with-generated.patch)
download | inline diff:
From 413bc70aaee9efe8cf40153bb31c80de69f5a909 Mon Sep 17 00:00:00 2001
From: jian he <[email protected]>
Date: Mon, 13 Apr 2026 22:48:47 +0800
Subject: [PATCH v2 1/1] COPY FORMAT JSON with generated
Author: SATYANARAYANA NARLAPURAM <satyanarlapuram(at)gmail(dot)com>
discussion: https://postgr.es/m/CAHg%2BQDcfpGDoPL3fvfjXRtfn%3Dfny6DdJR6BAy6TpS1Xj2EZfXA%40mail.gmail.com
commitfest entry: https://commitfest.postgresql.org/patch/
---
src/backend/commands/copyto.c | 2 +-
src/test/regress/expected/generated_stored.out | 6 ++++++
src/test/regress/expected/generated_virtual.out | 6 ++++++
src/test/regress/sql/generated_stored.sql | 3 +++
src/test/regress/sql/generated_virtual.sql | 3 +++
5 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/src/backend/commands/copyto.c b/src/backend/commands/copyto.c
index f0e0147c665..85d15353647 100644
--- a/src/backend/commands/copyto.c
+++ b/src/backend/commands/copyto.c
@@ -1033,7 +1033,7 @@ BeginCopyTo(ParseState *pstate,
{
cstate->json_buf = makeStringInfo();
- if (attnamelist != NIL && rel)
+ if (rel && list_length(cstate->attnumlist) < tupDesc->natts)
{
int natts = list_length(cstate->attnumlist);
TupleDesc resultDesc;
diff --git a/src/test/regress/expected/generated_stored.out b/src/test/regress/expected/generated_stored.out
index 43cddeac373..4d329c60994 100644
--- a/src/test/regress/expected/generated_stored.out
+++ b/src/test/regress/expected/generated_stored.out
@@ -541,6 +541,12 @@ SELECT * FROM gtest3 ORDER BY a;
4 | 12
(4 rows)
+-- COPY JSON should exclude generated columns, same as text/CSV
+COPY gtest1 TO stdout WITH (FORMAT json);
+{"a":1}
+{"a":2}
+{"a":3}
+{"a":4}
-- null values
CREATE TABLE gtest2 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (NULL) STORED);
INSERT INTO gtest2 VALUES (1);
diff --git a/src/test/regress/expected/generated_virtual.out b/src/test/regress/expected/generated_virtual.out
index 234061fa1f7..fc41c480d40 100644
--- a/src/test/regress/expected/generated_virtual.out
+++ b/src/test/regress/expected/generated_virtual.out
@@ -535,6 +535,12 @@ SELECT * FROM gtest3 ORDER BY a;
4 | 12
(4 rows)
+-- COPY JSON should exclude generated columns, same as text/CSV
+COPY gtest1 TO stdout WITH (FORMAT json);
+{"a":1}
+{"a":2}
+{"a":3}
+{"a":4}
-- null values
CREATE TABLE gtest2 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (NULL) VIRTUAL);
INSERT INTO gtest2 VALUES (1);
diff --git a/src/test/regress/sql/generated_stored.sql b/src/test/regress/sql/generated_stored.sql
index 280021d79b7..1064839dcd2 100644
--- a/src/test/regress/sql/generated_stored.sql
+++ b/src/test/regress/sql/generated_stored.sql
@@ -239,6 +239,9 @@ COPY gtest3 (a, b) FROM stdin;
SELECT * FROM gtest3 ORDER BY a;
+-- COPY JSON should exclude generated columns, same as text/CSV
+COPY gtest1 TO stdout WITH (FORMAT json);
+
-- null values
CREATE TABLE gtest2 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (NULL) STORED);
INSERT INTO gtest2 VALUES (1);
diff --git a/src/test/regress/sql/generated_virtual.sql b/src/test/regress/sql/generated_virtual.sql
index 4d9ad3c5dca..9b32413e3a9 100644
--- a/src/test/regress/sql/generated_virtual.sql
+++ b/src/test/regress/sql/generated_virtual.sql
@@ -239,6 +239,9 @@ COPY gtest3 (a, b) FROM stdin;
SELECT * FROM gtest3 ORDER BY a;
+-- COPY JSON should exclude generated columns, same as text/CSV
+COPY gtest1 TO stdout WITH (FORMAT json);
+
-- null values
CREATE TABLE gtest2 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (NULL) VIRTUAL);
INSERT INTO gtest2 VALUES (1);
--
2.34.1
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Subject: Re: Bug: COPY FORMAT JSON includes generated columns unlike text/CSV
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