From 4bea91f21f61d01bd40a4191a4a8c82d0959fffe Mon Sep 17 00:00:00 2001 From: Masahiko Sawada Date: Mon, 20 Oct 2025 10:38:52 -0700 Subject: Support COPY TO for partitioned tables. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Previously, COPY TO command didn't support directly specifying partitioned tables so users had to use COPY (SELECT ...) TO variant. This commit adds direct COPY TO support for partitioned tables, improving both usability and performance. Performance tests show it's faster than the COPY (SELECT ...) TO variant as it avoids the overheads of query processing and sending results to the COPY TO command. When used with partitioned tables, COPY TO copies the same rows as SELECT * FROM table. Row-level security policies of the partitioned table are applied in the same way as when executing COPY TO on a plain table. Author: jian he Reviewed-by: vignesh C Reviewed-by: David Rowley Reviewed-by: Melih Mutlu Reviewed-by: Kirill Reshke Reviewed-by: Atsushi Torikoshi Reviewed-by: Álvaro Herrera Reviewed-by: Masahiko Sawada Reviewed-by: Chao Li Discussion: https://postgr.es/m/CACJufxEZt%2BG19Ors3bQUq-42-61__C%3Dy5k2wk%3DsHEFRusu7%3DiQ%40mail.gmail.com --- contrib/postgres_fdw/expected/postgres_fdw.out | 5 +++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 3 +++ 2 files changed, 8 insertions(+) (limited to 'contrib/postgres_fdw') diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 91bbd0d8c73..cd28126049d 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -11599,6 +11599,11 @@ SELECT * FROM result_tbl ORDER BY a; (3 rows) DELETE FROM result_tbl; +-- Test COPY TO when foreign table is partition +COPY async_pt TO stdout; --error +ERROR: cannot copy from foreign table "async_p1" +DETAIL: Partition "async_p1" is a foreign table in partitioned table "async_pt" +HINT: Try the COPY (SELECT ...) TO variant. DROP FOREIGN TABLE async_p3; DROP TABLE base_tbl3; -- Check case where the partitioned table has local/remote partitions diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index 3b7da128519..9a8f9e28135 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -3941,6 +3941,9 @@ INSERT INTO result_tbl SELECT * FROM async_pt WHERE b === 505; SELECT * FROM result_tbl ORDER BY a; DELETE FROM result_tbl; +-- Test COPY TO when foreign table is partition +COPY async_pt TO stdout; --error + DROP FOREIGN TABLE async_p3; DROP TABLE base_tbl3; -- cgit v1.2.3