diff --git a/src/backend/executor/execProcnode.c b/src/backend/executor/execProcnode.c
index 9befca9016..fcb8b56999 100644
--- a/src/backend/executor/execProcnode.c
+++ b/src/backend/executor/execProcnode.c
@@ -370,12 +370,7 @@ ExecInitNode(Plan *node, EState *estate, int eflags)
 			break;
 	}
 
-	/*
-	 * Add a wrapper around the ExecProcNode callback that checks stack depth
-	 * during the first execution.
-	 */
-	result->ExecProcNodeReal = result->ExecProcNode;
-	result->ExecProcNode = ExecProcNodeFirst;
+	ExecSetExecProcNode(result, result->ExecProcNode);
 
 	/*
 	 * Initialize any initPlans present in this node.  The planner put them in
@@ -401,6 +396,27 @@ ExecInitNode(Plan *node, EState *estate, int eflags)
 }
 
 
+/*
+ * If a node wants to change its ExecProcNode function after ExecInitNode()
+ * has finished, it should do so with this function.  That way any wrapper
+ * functions can be reinstalled, without the node having to know how that
+ * works.
+ */
+void
+ExecSetExecProcNode(PlanState *node, ExecProcNodeMtd function)
+{
+	/*
+	 * Add a wrapper around the ExecProcNode callback that checks stack depth
+	 * during the first execution and maybe adds an instrumentation
+	 * wrapper. When the callback is changed after execution has already begun
+	 * that means we'll superflously execute ExecProcNodeFirst, but that seems
+	 * ok.
+	 */
+	node->ExecProcNodeReal = function;
+	node->ExecProcNode = ExecProcNodeFirst;
+}
+
+
 /*
  * ExecProcNode wrapper that performs some one-time checks, before calling
  * the relevant node method (possibly via an instrumentation wrapper).
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index b5578f5855..dea9216fd6 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -219,6 +219,7 @@ extern void EvalPlanQualEnd(EPQState *epqstate);
  * functions in execProcnode.c
  */
 extern PlanState *ExecInitNode(Plan *node, EState *estate, int eflags);
+extern void ExecSetExecProcNode(PlanState *node, ExecProcNodeMtd function);
 extern Node *MultiExecProcNode(PlanState *node);
 extern void ExecEndNode(PlanState *node);
 extern bool ExecShutdownNode(PlanState *node);