From 6c72c884954a4223fad192ff021803bf7835e7d7 Mon Sep 17 00:00:00 2001
From: Yugo Nagata <nagata@sraoss.co.jp>
Date: Fri, 15 Nov 2024 15:07:17 +0900
Subject: [PATCH] Prohibit materialized views to use ephemeral named relations

---
 src/backend/parser/analyze.c        | 11 ++++++--
 src/backend/parser/parse_relation.c | 43 ++++++++++++++++++++++++++++-
 src/include/parser/parse_relation.h |  1 +
 3 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 506e063161..c96088c2cc 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -3125,15 +3125,20 @@ transformCreateTableAsStmt(ParseState *pstate, CreateTableAsStmt *stmt)
 					 errmsg("materialized views must not use data-modifying statements in WITH")));
 
 		/*
-		 * Check whether any temporary database objects are used in the
-		 * creation query. It would be hard to refresh data or incrementally
-		 * maintain it if a source disappeared.
+		 * Check whether any temporary database objects or ephemeral named
+		 * relations are used in the creation query. It would be hard to refresh
+		 * data or incrementally maintain it if a source disappeared.
 		 */
 		if (isQueryUsingTempRelation(query))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("materialized views must not use temporary tables or views")));
 
+		if (isQueryUsingENR(query))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("materialized views must not use ephemeral named relations")));
+
 		/*
 		 * A materialized view would either need to save parameters for use in
 		 * maintaining/loading the data or prohibit them entirely.  The latter
diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c
index 8075b1b8a1..0e9cb7a1c6 100644
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -102,6 +102,7 @@ static int	specialAttNum(const char *attname);
 static bool rte_visible_if_lateral(ParseState *pstate, RangeTblEntry *rte);
 static bool rte_visible_if_qualified(ParseState *pstate, RangeTblEntry *rte);
 static bool isQueryUsingTempRelation_walker(Node *node, void *context);
+static bool isQueryUsingENR_walker(Node *node, void *context);
 
 
 /*
@@ -3893,7 +3894,7 @@ rte_visible_if_qualified(ParseState *pstate, RangeTblEntry *rte)
 
 /*
  * Examine a fully-parsed query, and return true iff any relation underlying
- * the query is a temporary relation (table, view, or materialized view).
+ * the query is an ephemeral named relation.
  */
 bool
 isQueryUsingTempRelation(Query *query)
@@ -3938,6 +3939,46 @@ isQueryUsingTempRelation_walker(Node *node, void *context)
 								  context);
 }
 
+/*
+ * Examine a fully-parsed query, and return true iff any relation underlying
+ * the query is an ephemeral named relation.
+ */
+bool
+isQueryUsingENR(Query *query)
+{
+	return isQueryUsingENR_walker((Node *) query, NULL);
+}
+
+static bool
+isQueryUsingENR_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+
+	if (IsA(node, Query))
+	{
+		Query	   *query = (Query *) node;
+		ListCell   *rtable;
+
+		foreach(rtable, query->rtable)
+		{
+			RangeTblEntry *rte = lfirst(rtable);
+
+			if (rte->rtekind == RTE_NAMEDTUPLESTORE)
+				return true;
+		}
+
+		return query_tree_walker(query,
+								 isQueryUsingENR_walker,
+								 context,
+								 QTW_IGNORE_JOINALIASES);
+	}
+
+	return expression_tree_walker(node,
+								  isQueryUsingENR_walker,
+								  context);
+}
+
 /*
  * addRTEPermissionInfo
  *		Creates RTEPermissionInfo for a given RTE and adds it into the
diff --git a/src/include/parser/parse_relation.h b/src/include/parser/parse_relation.h
index 91fd8e243b..2849da7fbd 100644
--- a/src/include/parser/parse_relation.h
+++ b/src/include/parser/parse_relation.h
@@ -127,5 +127,6 @@ extern const NameData *attnumAttName(Relation rd, int attid);
 extern Oid	attnumTypeId(Relation rd, int attid);
 extern Oid	attnumCollationId(Relation rd, int attid);
 extern bool isQueryUsingTempRelation(Query *query);
+extern bool isQueryUsingENR(Query *query);
 
 #endif							/* PARSE_RELATION_H */
-- 
2.34.1