Subject: [PATCH] Fix quotation logic for unreserved keywords in window specifications

From: Kwangwon Seo <[email-masked]>
Date: Fri, 10 Jul 2026 18:28:23 +0900

Hi hackers,

I was testing views with pg_dump/pg_restore and found a case where an
unreserved keyword is not quoted correctly.

example:

-- Just a base table
CREATE TABLE t (v int);
INSERT INTO t VALUES (1), (2);

-- Create a view
CREATE VIEW v AS
SELECT count(*) OVER w2 FROM t
WINDOW "rows" AS (PARTITION BY v), w2 AS ("rows" ORDER BY v);

But the problem is, here, that quotation is gone.

-- Problem: Quotation is disappared
SELECT pg_get_viewdef('v');
                       pg_get_viewdef
-------------------------------------------------------------
  SELECT count(*) OVER w2 AS count                          +
    FROM t                                                  +
   WINDOW rows AS (PARTITION BY v), w2 AS (rows ORDER BY v);
(1 row)

-- If you use this for recovering the view above, You'll face this error.
 SELECT count(*) OVER w2 AS count
        FROM t
        WINDOW rows AS (PARTITION BY v), w2 AS (rows ORDER BY v);
ERROR:  syntax error at or near "ORDER"
LINE 3:  WINDOW rows AS (PARTITION BY v), w2 AS (rows ORDER BY v);

This breaks pg_dump/restore: the view is lost.
As a result, pg_dump/pg_restore cannot restore the view successfully.

Fortunately, I found this comment in the gram.y:

It says:

 * If we see PARTITION, RANGE, ROWS or GROUPS as the first token after the
'('
 * of a window_specification, we want the assumption to be that there is
 * no existing_window_name; but those keywords are unreserved and so could
 * be ColIds.

I think that assumption can be broken when inheritance is used
across multiple window definitions.
I mean this: w2 AS ("rows" ORDER BY v)

Some comments for patch file:

The attached patch quotes the window name when it is a keyword
in get_rule_windowspec().
Output for ordinary window names is unchanged. The window definition itself
is a ColId so no change is needed there; only the refname is quoted.

Maybe this is a known thing on the team's side, but I think, at least,
should not break
compatibility with current tools. That is the motivation of this patch...

I'd appreciate any feedback or suggestions...!!

Best regards...
From 72c0dd0ea78155daa348845fcd74b9102a404056 Mon Sep 17 00:00:00 2001
From: Kwangwon Seo <[email-masked]>
Date: Fri, 10 Jul 2026 16:26:33 +0900
Subject: [PATCH v1] Fix quotation logic for unreserved keywords in window
 specifications

---
 src/backend/utils/adt/ruleutils.c    | 30 +++++++++++++++++++++++++++-
 src/test/regress/expected/window.out | 12 +++++++++++
 src/test/regress/sql/window.sql      |  7 +++++++
 3 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 819631781c0..6084b48f435 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -450,6 +450,7 @@ static void get_rule_orderby(List *orderList, List *targetList,
 static void get_rule_windowclause(Query *query, deparse_context *context);
 static void get_rule_windowspec(WindowClause *wc, List *targetList,
 								deparse_context *context);
+static void appendWindowRefName(StringInfo buf, const char *refname);
 static void get_window_frame_options(int frameOptions,
 									 Node *startOffset, Node *endOffset,
 									 deparse_context *context);
@@ -7159,7 +7160,7 @@ get_rule_windowspec(WindowClause *wc, List *targetList,
 	appendStringInfoChar(buf, '(');
 	if (wc->refname)
 	{
-		appendStringInfoString(buf, quote_identifier(wc->refname));
+		appendWindowRefName(buf, wc->refname);
 		needspace = true;
 	}
 	/* partition clauses are always inherited, so only print if no refname */
@@ -7201,6 +7202,33 @@ get_rule_windowspec(WindowClause *wc, List *targetList,
 	appendStringInfoChar(buf, ')');
 }
 
+/*
+ * Emit the name of the window definition.
+ *
+ * PARTITION, RANGE, ROWS, and GROUPS have the same precedence as IDENT
+ * at the start of a window specification, preventing them from being
+ * recognized as an existing_window_name (see opt_existing_window_name
+ * in gram.y). Since these are unreserved keywords, quote_identifier()
+ * does not quote them, causing the generated SQL to fail when reparsed.
+ * Therefore, quote any keyword here rather than maintaining a list.
+ */
+static void
+appendWindowRefName(StringInfo buf, const char *refname)
+{
+	const char *quoted = quote_identifier(refname);
+
+	if (quoted == refname &&
+		ScanKeywordLookup(refname, &ScanKeywords) >= 0)
+	{
+		/* quote_identifier() left it bare, so it needs no escaping */
+		appendStringInfoChar(buf, '"');
+		appendStringInfoString(buf, refname);
+		appendStringInfoChar(buf, '"');
+	}
+	else
+		appendStringInfoString(buf, quoted);
+}
+
 /*
  * Append the description of a window's framing options to context->buf
  */
diff --git a/src/test/regress/expected/window.out b/src/test/regress/expected/window.out
index c0bde1c5eec..5080b415e0b 100644
--- a/src/test/regress/expected/window.out
+++ b/src/test/regress/expected/window.out
@@ -1361,6 +1361,18 @@ SELECT pg_get_viewdef('v_window');
     FROM generate_series(now(), (now() + '@ 100 days'::interval), '@ 1 hour'::interval) i(i);
 (1 row)
 
+-- A window name that is an unreserved keyword cannot be an existing_window_name
+CREATE TEMP VIEW v2_window_unreserved_kw AS
+	SELECT count(*) OVER w2 FROM generate_series(1, 1) s(v)
+  WINDOW "rows" AS (PARTITION BY v), w2 AS ("rows" ORDER BY v);
+SELECT pg_get_viewdef('v2_window_unreserved_kw');
+                        pg_get_viewdef                         
+---------------------------------------------------------------
+  SELECT count(*) OVER w2 AS count                            +
+    FROM generate_series(1, 1) s(v)                           +
+   WINDOW rows AS (PARTITION BY v), w2 AS ("rows" ORDER BY v);
+(1 row)
+
 -- test overflow frame specifications
 SELECT sum(unique1) over (rows between current row and 9223372036854775807 following exclude current row),
 	unique1, four
diff --git a/src/test/regress/sql/window.sql b/src/test/regress/sql/window.sql
index 8e6f92d94c7..396b95d0d39 100644
--- a/src/test/regress/sql/window.sql
+++ b/src/test/regress/sql/window.sql
@@ -330,6 +330,13 @@ CREATE TEMP VIEW v_window AS
 
 SELECT pg_get_viewdef('v_window');
 
+-- A window name that is an unreserved keyword cannot be an existing_window_name
+CREATE TEMP VIEW v2_window_unreserved_kw AS
+	SELECT count(*) OVER w2 FROM generate_series(1, 1) s(v)
+  WINDOW "rows" AS (PARTITION BY v), w2 AS ("rows" ORDER BY v);
+
+SELECT pg_get_viewdef('v2_window_unreserved_kw');
+
 -- test overflow frame specifications
 SELECT sum(unique1) over (rows between current row and 9223372036854775807 following exclude current row),
 	unique1, four
-- 
2.52.0