fix_hang_issue.patch

diff --git a/src/backend/executor/nodeAppend.c b/src/backend/executor/nodeAppend.c
index 64a17fb..2dbb658 100644
--- a/src/backend/executor/nodeAppend.c
+++ b/src/backend/executor/nodeAppend.c
@@ -456,6 +456,8 @@ choose_next_subplan_for_worker(AppendState *node)
 {
 	ParallelAppendState *pstate = node->as_pstate;
 	Append	   *append = (Append *) node->ps.plan;
+	int			initial_plan;
+	bool		should_wrap_around;
 
 	/* Backward scan is not supported by parallel-aware plans */
 	Assert(ScanDirectionIsForward(node->ps.state->es_direction));
@@ -473,6 +475,14 @@ choose_next_subplan_for_worker(AppendState *node)
 		return false;
 	}
 
+	/*
+	 * If we are starting the search from a non-partial plan, no point in
+	 * looping back to the first partial plan: we would have covered all the
+	 * plans by the time we reach the last plan.
+	 */
+	initial_plan = pstate->pa_next_plan;
+	should_wrap_around = (initial_plan >= append->first_partial_plan);
+
 	/* Loop until we find a subplan to execute. */
 	while (pstate->pa_finished[pstate->pa_next_plan])
 	{
@@ -481,18 +491,18 @@ choose_next_subplan_for_worker(AppendState *node)
 			/* Advance to next plan. */
 			pstate->pa_next_plan++;
 		}
-		else if (append->first_partial_plan < node->as_nplans)
+		else if (!should_wrap_around)
 		{
-			/* Loop back to first partial plan. */
-			pstate->pa_next_plan = append->first_partial_plan;
+			/* Covered all plans, arrange to bail out. */
+			pstate->pa_next_plan = initial_plan;
 		}
 		else
 		{
-			/* At last plan, no partial plans, arrange to bail out. */
-			pstate->pa_next_plan = node->as_whichplan;
+			/* Loop back to first partial plan. */
+			pstate->pa_next_plan = append->first_partial_plan;
 		}
 
-		if (pstate->pa_next_plan == node->as_whichplan)
+		if (pstate->pa_next_plan == initial_plan)
 		{
 			/* We've tried everything! */
 			pstate->pa_next_plan = INVALID_SUBPLAN_INDEX;