Add AppendDistributedTablePlacementNodeList function

src/backend/distributed/operations/stage_protocol.c

@@ -166,7 +166,7 @@ master_create_empty_shard(PG_FUNCTION_ARGS)
 	uint64 shardId = GetNextShardId();
 
 	/* if enough live groups, add an extra candidate node as backup */
-	List *workerNodeList = DistributedTablePlacementNodeList(NoLock);
+	List *workerNodeList = AppendDistributedTablePlacementNodeList(NoLock);
 
 	if (list_length(workerNodeList) > ShardReplicationFactor)
 	{

src/backend/distributed/operations/worker_node_manager.c

@@ -499,6 +499,19 @@ DistributedTablePlacementNodeList(LOCKMODE lockMode)
 }
 
 
+/*
+ * AppendDistributedTablePlacementNodeList returns a list of all active, primary
+ * worker nodes that can store new data, i.e shouldstoreshards is 'true', and are
+ * not the coordinator
+ */
+List *
+AppendDistributedTablePlacementNodeList(LOCKMODE lockMode)
+{
+	EnsureModificationsCanRun();
+	return FilterActiveNodeListFunc(lockMode, NodeCanHaveAppendDistTablePlacements);
+}
+
+
 /*
  * NodeCanHaveDistTablePlacements returns true if the given node can have
  * shards of a distributed table.
@@ -515,6 +528,22 @@ NodeCanHaveDistTablePlacements(WorkerNode *node)
 }
 
 
+/*
+ * NodeCanHaveAppendDistTablePlacements returns true if the given node can have
+ * shards of a distributed table, and is not the coordinator
+ */
+bool
+NodeCanHaveAppendDistTablePlacements(WorkerNode *node)
+{
+	if (!NodeIsPrimary(node))
+	{
+		return false;
+	}
+
+	return node->shouldHaveShards && (node->groupId != 0);
+}
+
+
 /*
  * ActiveReadableNonCoordinatorNodeList returns a list of all nodes in workerNodeHash
  * that are readable nodes This method excludes coordinator.

src/include/distributed/worker_manager.h

@@ -79,7 +79,9 @@ extern List * ReferenceTablePlacementNodeList(LOCKMODE lockMode);
 extern WorkerNode * CoordinatorNodeIfAddedAsWorkerOrError(void);
 extern void ErrorIfCoordinatorNotAddedAsWorkerNode(void);
 extern List * DistributedTablePlacementNodeList(LOCKMODE lockMode);
+extern List * AppendDistributedTablePlacementNodeList(LOCKMODE lockMode);
 extern bool NodeCanHaveDistTablePlacements(WorkerNode *node);
+extern bool NodeCanHaveAppendDistTablePlacements(WorkerNode *node);
 extern uint32 ActiveReadableNonCoordinatorNodeCount(void);
 extern List * ActiveReadableNonCoordinatorNodeList(void);
 extern List * ActiveReadableNodeList(void);