From: Andrew Dunstan <andrew@dunslane.net>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: json format for COPY TO
Date: Fri, 20 Mar 2026 12:41:00 +0000
Message-ID: <E1w3Z9v-000dj4-1t@gemulon.postgresql.org> (raw)
json format for COPY TO
This introduces the JSON format option for the COPY TO command, allowing
users to export query results or table data directly as a stream of JSON
objects (one per line, NDJSON style).
The JSON format is currently supported only for COPY TO operations; it
is not available for COPY FROM.
JSON format is incompatible with some standard text/CSV formatting
options, including HEADER, DEFAULT, NULL, DELIMITER, FORCE QUOTE,
FORCE NOT NULL, and FORCE NULL.
Column list support is included: when a column list is specified, only
the named columns are emitted in each JSON object.
Regression tests covering valid JSON exports and error handling for
incompatible options have been added to src/test/regress/sql/copy.sql.
Author: Joe Conway <mail@joeconway.com>
Author: jian he <jian.universality@gmail.com>
Co-Authored-By: Andrew Dunstan <andrew@dunslane.net>
Reviewed-by: Andrey M. Borodin <x4mmm@yandex-team.ru>
Reviewed-by: Dean Rasheed <dean.a.rasheed@gmail.com>
Reviewed-by: Daniel Verite <daniel@manitou-mail.org>
Reviewed-by: Davin Shearer <davin@apache.org>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Junwang Zhao <zhjwpku@gmail.com>
Discussion: https://postgr.es/m/CALvfUkBxTYy5uWPFVwpk_7ii2zgT07t3d-yR_cy4sfrrLU%3Dkcg%40mail.gmail.com
Discussion: https://postgr.es/m/6a04628d-0d53-41d9-9e35-5a8dc302c34c@joeconway.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/7dadd38cda95bf5bc0c4715d9ab71766d1693379
Modified Files
--------------
doc/src/sgml/ref/copy.sgml | 29 ++++++-
src/backend/commands/copy.c | 53 ++++++++----
src/backend/commands/copyto.c | 162 ++++++++++++++++++++++++++++++++++---
src/backend/parser/gram.y | 8 ++
src/backend/utils/adt/json.c | 5 +-
src/bin/psql/tab-complete.in.c | 2 +-
src/include/commands/copy.h | 1 +
src/include/utils/json.h | 2 +
src/test/regress/expected/copy.out | 146 +++++++++++++++++++++++++++++++++
src/test/regress/sql/copy.sql | 88 ++++++++++++++++++++
10 files changed, 463 insertions(+), 33 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: andrew@dunslane.net, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: json format for COPY TO
In-Reply-To: <E1w3Z9v-000dj4-1t@gemulon.postgresql.org>
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