Skip dependency setup on coordinator node

src/backend/distributed/metadata/node_metadata.c

@@ -380,6 +380,9 @@ master_set_node_property(PG_FUNCTION_ARGS)
  * - All dependencies (e.g., types, schemas)
  * - Reference tables, because they are needed to handle queries efficiently.
  * - Distributed functions
+ *
+ * Note that we do not create the distributed dependencies on the coordinator
+ * since all the dependencies should be present in the coordinator already.
  */
 static void
 SetUpDistributedTableDependencies(WorkerNode *newWorkerNode)
@@ -388,13 +391,13 @@ SetUpDistributedTableDependencies(WorkerNode *newWorkerNode)
 	{
 		EnsureNoModificationsHaveBeenDone();
 
-		if (ShouldPropagate())
+		if (ShouldPropagate() && !NodeIsCoordinator(newWorkerNode))
 		{
 			PropagateNodeWideObjects(newWorkerNode);
 			ReplicateAllDependenciesToNode(newWorkerNode->workerName,
 										   newWorkerNode->workerPort);
 		}
-		else
+		else if (!NodeIsCoordinator(newWorkerNode))
 		{
 			ereport(WARNING, (errmsg("citus.enable_object_propagation is off, not "
 									 "creating distributed objects on worker"),

src/test/regress/expected/local_shard_copy.out

@@ -4,18 +4,6 @@ SET client_min_messages TO DEBUG;
 SET citus.next_shard_id TO 1570000;
 SET citus.replicate_reference_tables_on_activate TO off;
 SELECT * FROM master_add_node('localhost', :master_port, groupid := 0);
-DEBUG:  schema "public" already exists, skipping
-DETAIL:  from localhost:xxxxx
-DEBUG:  extension "plpgsql" already exists, skipping
-DETAIL:  from localhost:xxxxx
-DEBUG:  schema "citus_mx_test_schema" already exists, skipping
-DETAIL:  from localhost:xxxxx
-DEBUG:  schema "citus_mx_test_schema_join_1" already exists, skipping
-DETAIL:  from localhost:xxxxx
-DEBUG:  schema "citus_mx_test_schema_join_2" already exists, skipping
-DETAIL:  from localhost:xxxxx
-DEBUG:  schema "citus_mx_schema_for_xacts" already exists, skipping
-DETAIL:  from localhost:xxxxx
  master_add_node
 ---------------------------------------------------------------------
               32

src/test/regress/expected/replicate_reference_tables_to_coordinator.out

@@ -427,6 +427,18 @@ ROLLBACK;
 -- see https://github.com/citusdata/citus/issues/3279
 ALTER TABLE squares DROP COLUMN b;
 NOTICE:  executing the command locally: SELECT worker_apply_shard_ddl_command (8000000, 'replicate_ref_to_coordinator', 'ALTER TABLE squares DROP COLUMN b;')
+-- verify that we replicate the reference tables that are distributed before
+-- adding the coordinator as a worker.
+SELECT master_remove_node('localhost', :master_port);
+ master_remove_node
+---------------------------------------------------------------------
+
+(1 row)
+
+-- add the coordinator as a worker node and verify that the reference tables are replicated
+SELECT master_add_node('localhost', :master_port, groupid => 0) AS master_nodeid \gset
+NOTICE:  Replicating reference table "squares" to the node localhost:xxxxx
+NOTICE:  Replicating reference table "numbers" to the node localhost:xxxxx
 -- clean-up
 SET client_min_messages TO ERROR;
 DROP SCHEMA replicate_ref_to_coordinator CASCADE;

src/test/regress/sql/replicate_reference_tables_to_coordinator.sql

@@ -250,6 +250,12 @@ ROLLBACK;
 -- see https://github.com/citusdata/citus/issues/3279
 ALTER TABLE squares DROP COLUMN b;
 
+-- verify that we replicate the reference tables that are distributed before
+-- adding the coordinator as a worker.
+SELECT master_remove_node('localhost', :master_port);
+
+-- add the coordinator as a worker node and verify that the reference tables are replicated
+SELECT master_add_node('localhost', :master_port, groupid => 0) AS master_nodeid \gset
 
 -- clean-up
 SET client_min_messages TO ERROR;