Only warn about reference tables when removing last node

src/backend/distributed/metadata/node_metadata.c

@@ -1292,7 +1292,7 @@ RemoveNodeFromCluster(char *nodeName, int32 nodePort)
 		}
 		if (NodeGroupHasLivePlacements(workerNode->groupId))
 		{
-			if (ClusterHasReferenceTable())
+			if (ActivePrimaryNodeCount() == 1 && ClusterHasReferenceTable())
 			{
 				ereport(ERROR, (errmsg(
 									"cannot remove the last worker node because there are reference "

src/test/regress/expected/multi_cluster_management.out

@@ -136,6 +136,10 @@ SELECT create_reference_table('test_reference_table');
 (1 row)
 
 INSERT INTO test_reference_table VALUES (1, '1');
+-- try to remove a node with active placements and reference tables
+SELECT citus_remove_node('localhost', :worker_2_port);
+ERROR:  cannot remove the primary node of a node group which has shard placements
+HINT:  To proceed, either drop the distributed tables or use undistribute_table() function to convert them to local tables
 -- try to disable a node with active placements see that node is removed
 -- observe that a notification is displayed
 SELECT master_disable_node('localhost', :worker_2_port);

src/test/regress/sql/multi_cluster_management.sql

@@ -54,6 +54,9 @@ CREATE TABLE test_reference_table (y int primary key, name text);
 SELECT create_reference_table('test_reference_table');
 INSERT INTO test_reference_table VALUES (1, '1');
 
+-- try to remove a node with active placements and reference tables
+SELECT citus_remove_node('localhost', :worker_2_port);
+
 -- try to disable a node with active placements see that node is removed
 -- observe that a notification is displayed
 SELECT master_disable_node('localhost', :worker_2_port);