v2-0001-COPY-TO-provide-hint-when-WHERE-clause-is-used.patch

application/x-patch

Filename: v2-0001-COPY-TO-provide-hint-when-WHERE-clause-is-used.patch
Type: application/x-patch
Part: 0
Message: Re: COPY TO: provide hint when WHERE clause is used

Patch

Same data as JSON: GET /api/v1/attachments/:id/patch the parsed metadata as JSON — format, series position, per-file stats; never the diff bytes. API reference →
Format: format-patch
Series: patch v2-0001
Subject: COPY TO: provide hint when WHERE clause is used
File+
src/backend/parser/gram.y 1 0
src/test/regress/expected/copy2.out 1 0
From 90cbddde61c4028a44654005a4e417c74e303d16 Mon Sep 17 00:00:00 2001
From: Atsushi Torikoshi <torikoshia@oss.nttdata.com>
Date: Mon, 1 Sep 2025 07:35:12 +0900
Subject: [PATCH v2] COPY TO: provide hint when WHERE clause is used

Provide a hint suggesting COPY TO when a WHERE clause is
specified, similar to the hint already given for views or others.
---
 src/backend/parser/gram.y           | 1 +
 src/test/regress/expected/copy2.out | 1 +
 2 files changed, 2 insertions(+)

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..9fd48acb1f8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -3442,6 +3442,7 @@ CopyStmt:	COPY opt_binary qualified_name opt_column_list
 						ereport(ERROR,
 								(errcode(ERRCODE_SYNTAX_ERROR),
 								 errmsg("WHERE clause not allowed with COPY TO"),
+								 errhint("Try the COPY (SELECT ... WHERE ...) TO variant."),
 								 parser_errposition(@11)));
 
 					n->options = NIL;
diff --git a/src/test/regress/expected/copy2.out b/src/test/regress/expected/copy2.out
index caa3c44f0d0..f3fdce23459 100644
--- a/src/test/regress/expected/copy2.out
+++ b/src/test/regress/expected/copy2.out
@@ -163,6 +163,7 @@ COPY x TO stdout WHERE a = 1;
 ERROR:  WHERE clause not allowed with COPY TO
 LINE 1: COPY x TO stdout WHERE a = 1;
                          ^
+HINT:  Try the COPY (SELECT ... WHERE ...) TO variant.
 COPY x from stdin WHERE a = 50004;
 COPY x from stdin WHERE a > 60003;
 COPY x from stdin WHERE f > 60003;
-- 
2.48.1