From 360dd14d8aa1e357c9e408823bded61162c8cb1f Mon Sep 17 00:00:00 2001
From: Marco Slot <marco.slot@gmail.com>
Date: Sat, 27 Nov 2021 11:52:29 +0100
Subject: [PATCH] Avoid failover during re-partition joins

---
 .../distributed/planner/multi_physical_planner.c       | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/backend/distributed/planner/multi_physical_planner.c b/src/backend/distributed/planner/multi_physical_planner.c
index d95040049..d993c9071 100644
--- a/src/backend/distributed/planner/multi_physical_planner.c
+++ b/src/backend/distributed/planner/multi_physical_planner.c
@@ -5398,6 +5398,16 @@ ActiveShardPlacementLists(List *taskList)
 		/* sort shard placements by their creation time */
 		activeShardPlacementList = SortList(activeShardPlacementList,
 											CompareShardPlacements);
+
+		/*
+		 * The executor currently does not know how to handle map task failover,
+		 * so we generate at most 1 placement.
+		 */
+		if (task->taskType == MAP_TASK)
+		{
+			activeShardPlacementList = list_make1(linitial(activeShardPlacementList));
+		}
+
 		shardPlacementLists = lappend(shardPlacementLists, activeShardPlacementList);
 	}