diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 759566a..3b9715b 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -100,6 +100,7 @@ typedef struct
 	bool		allow_restricted;
 } has_parallel_hazard_arg;
 
+static List *get_opargs(const Expr *clause);
 static bool aggregates_allow_partial_walker(Node *node,
 											partial_agg_context *context);
 static bool contain_agg_clause_walker(Node *node, void *context);
@@ -197,6 +198,19 @@ make_opclause(Oid opno, Oid opresulttype, bool opretset,
 	return (Expr *) expr;
 }
 
+static List *
+get_opargs(const Expr *clause)
+{
+	if (IsA(clause, OpExpr))
+		return ((OpExpr *) clause)->args;
+
+	if (IsA(clause, ScalarArrayOpExpr))
+		return ((ScalarArrayOpExpr *) clause)->args;
+
+	elog(ERROR, "unrecognized node type: %d",
+			(int) nodeTag(clause));
+}
+
 /*
  * get_leftop
  *
@@ -206,10 +220,10 @@ make_opclause(Oid opno, Oid opresulttype, bool opretset,
 Node *
 get_leftop(const Expr *clause)
 {
-	const OpExpr *expr = (const OpExpr *) clause;
+	const List *args = get_opargs(clause);
 
-	if (expr->args != NIL)
-		return linitial(expr->args);
+	if (args != NIL)
+		return linitial(args);
 	else
 		return NULL;
 }
@@ -223,10 +237,10 @@ get_leftop(const Expr *clause)
 Node *
 get_rightop(const Expr *clause)
 {
-	const OpExpr *expr = (const OpExpr *) clause;
+	const List *args = get_opargs(clause);
 
-	if (list_length(expr->args) >= 2)
-		return lsecond(expr->args);
+	if (list_length(args) >= 2)
+		return lsecond(args);
 	else
 		return NULL;
 }