nocfbot-0005-Sync-stale-comments-on-DEFINE-PATTERN-handling.txt

From 5dcb8f07457f058c707c80c9c793c4fa38b34794 Mon Sep 17 00:00:00 2001
From: Henson Choi <assam258@gmail.com>
Date: Tue, 5 May 2026 11:44:45 +0900
Subject: [PATCH 05/26] Sync stale comments on DEFINE/PATTERN handling

validateRPRPatternVarCount() validates DEFINE names against the
PATTERN list and rejects any not used in PATTERN; the surrounding
comments said it "collected" them.  Align the function header,
inline block comment, and the call-site comment.  Also fix the
matching SELECT doc ("filtered during planning" -> "rejected with
an error") and the XXX note's wording.
---
 doc/src/sgml/ref/select.sgml   |  4 ++--
 src/backend/parser/parse_rpr.c | 28 ++++++++++++++--------------
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml
index 5272d6c0bfa..e4708331439 100644
--- a/doc/src/sgml/ref/select.sgml
+++ b/doc/src/sgml/ref/select.sgml
@@ -1192,8 +1192,8 @@ DEFINE <replaceable class="parameter">definition_variable_name</replaceable> AS
 </synopsis>
 
     Conversely, variables defined in the <literal>DEFINE</literal> clause
-    but not used in the <literal>PATTERN</literal> clause are filtered out
-    during query planning.
+    but not used in the <literal>PATTERN</literal> clause are rejected
+    with an error.
    </para>
 
    <para>
diff --git a/src/backend/parser/parse_rpr.c b/src/backend/parser/parse_rpr.c
index 87411abcbe2..2c6fccebd47 100644
--- a/src/backend/parser/parse_rpr.c
+++ b/src/backend/parser/parse_rpr.c
@@ -183,11 +183,11 @@ transformRPR(ParseState *pstate, WindowClause *wc, WindowDef *windef,
  * Recursively traverses the pattern tree, collecting unique variable names.
  * Throws an error if the number of unique variables exceeds RPR_VARID_MAX.
  *
- * If rpDefs is non-NULL, DEFINE variable names are also collected into
- * varNames so that transformColumnRef can distinguish pattern variable
- * qualifiers from FROM-clause range variables.
- *
- * varNames is both input and output: existing names are preserved, new ones added.
+ * If rpDefs is non-NULL, each DEFINE variable name is also validated against
+ * varNames; any DEFINE name not present in PATTERN is rejected with an error.
+ * varNames itself is not extended by this step -- it carries only PATTERN
+ * variable names, which is what transformColumnRef checks via
+ * p_rpr_pattern_vars to identify pattern variable qualifiers.
  */
 static void
 validateRPRPatternVarCount(ParseState *pstate, RPRPatternNode *node,
@@ -244,10 +244,10 @@ validateRPRPatternVarCount(ParseState *pstate, RPRPatternNode *node,
 	}
 
 	/*
-	 * After the top-level call, also collect DEFINE variable names that are
-	 * not already in the list.  This is only done once at the outermost
-	 * recursion level, detected by rpDefs being non-NULL (recursive calls
-	 * pass NULL).
+	 * After the top-level call, validate that every DEFINE variable name is
+	 * present in the PATTERN variable list; reject names not used in PATTERN.
+	 * This is only done once at the outermost recursion level, detected by
+	 * rpDefs being non-NULL (recursive calls pass NULL).
 	 */
 	if (rpDefs)
 	{
@@ -293,9 +293,9 @@ validateRPRPatternVarCount(ParseState *pstate, RPRPatternNode *node,
  * Note: Variables not in DEFINE are evaluated as TRUE by the executor.
  * Variables in DEFINE but not in PATTERN are rejected as an error.
  *
- * XXX Pattern variable qualified column references in DEFINE (e.g.
- * "A.price") are not yet supported.  Currently rejected by
- * transformColumnRef in parse_expr.c via the p_rpr_pattern_vars check.
+ * XXX Pattern variable qualified expressions in DEFINE (e.g. "A.price")
+ * are not yet supported.  Currently rejected by transformColumnRef in
+ * parse_expr.c via the p_rpr_pattern_vars check.
  */
 static List *
 transformDefineClause(ParseState *pstate, WindowClause *wc, WindowDef *windef,
@@ -317,8 +317,8 @@ transformDefineClause(ParseState *pstate, WindowClause *wc, WindowDef *windef,
 	Assert(windef->rpCommonSyntax->rpDefs != NULL);
 
 	/*
-	 * Validate PATTERN variable count and collect all RPR variable names
-	 * (PATTERN + DEFINE) for use in transformColumnRef.
+	 * Validate PATTERN variable count, reject DEFINE variables not used in
+	 * PATTERN, and collect PATTERN variable names for transformColumnRef.
 	 */
 	validateRPRPatternVarCount(pstate, windef->rpCommonSyntax->rpPattern,
 							   windef->rpCommonSyntax->rpDefs,
-- 
2.50.1 (Apple Git-155)