diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 5a946cdfe9..7f4bb7b99a 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -27,6 +27,7 @@
 
 #include "catalog/pg_type.h"
 #include "funcapi.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
@@ -315,6 +316,9 @@ static Node *
 pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode,
 								  Relids *relids)
 {
+	/* Since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (jtnode == NULL)
 	{
 		*relids = NULL;
@@ -812,6 +816,11 @@ pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
 						   JoinExpr *lowest_nulling_outer_join,
 						   AppendRelInfo *containing_appendrel)
 {
+	/* Since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+	/* Also, since it's a bit expensive, let's check for query cancel. */
+	CHECK_FOR_INTERRUPTS();
+
 	Assert(jtnode != NULL);
 	if (IsA(jtnode, RangeTblRef))
 	{
@@ -1941,6 +1950,9 @@ is_simple_union_all(Query *subquery)
 static bool
 is_simple_union_all_recurse(Node *setOp, Query *setOpQuery, List *colTypes)
 {
+	/* Since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (IsA(setOp, RangeTblRef))
 	{
 		RangeTblRef *rtr = (RangeTblRef *) setOp;