From 4bea91f21f61d01bd40a4191a4a8c82d0959fffe Mon Sep 17 00:00:00 2001
From: Masahiko Sawada <msawada@postgresql.org>
Date: Mon, 20 Oct 2025 10:38:52 -0700
Subject: Support COPY TO for partitioned tables.
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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 <jian.universality@gmail.com>
Reviewed-by: vignesh C <vignesh21@gmail.com>
Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Melih Mutlu <m.melihmutlu@gmail.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Atsushi Torikoshi <torikoshia@oss.nttdata.com>
Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://postgr.es/m/CACJufxEZt%2BG19Ors3bQUq-42-61__C%3Dy5k2wk%3DsHEFRusu7%3DiQ%40mail.gmail.com
---
 doc/src/sgml/ref/copy.sgml | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

(limited to 'doc/src/sgml/ref/copy.sgml')

diff --git a/doc/src/sgml/ref/copy.sgml b/doc/src/sgml/ref/copy.sgml
index c2d1fbc1fbe..fdc24b36bb8 100644
--- a/doc/src/sgml/ref/copy.sgml
+++ b/doc/src/sgml/ref/copy.sgml
@@ -539,13 +539,14 @@ COPY <replaceable class="parameter">count</replaceable>
 
    <para>
     <command>COPY TO</command> can be used with plain
-    tables and populated materialized views.
-    For example,
-    <literal>COPY <replaceable class="parameter">table</replaceable>
-    TO</literal> copies the same rows as
+    tables, populated materialized views, and partitioned tables.
+    For non-partitioned tables, COPY <replaceable class="parameter">table</replaceable>
+    copies the same rows as
     <literal>SELECT * FROM ONLY <replaceable class="parameter">table</replaceable></literal>.
+    For partitioned tables, it copies the same rows as
+    <literal>SELECT * FROM <replaceable class="parameter">table</replaceable></literal>.
     However it doesn't directly support other relation types,
-    such as partitioned tables, inheritance child tables, or views.
+    such as inheritance child tables, or views.
     To copy all rows from such relations, use <literal>COPY (SELECT * FROM
     <replaceable class="parameter">table</replaceable>) TO</literal>.
    </para>
-- 
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