Introduces citus_coordinator_node_id

src/backend/distributed/metadata/node_metadata.c

@@ -126,6 +126,7 @@ static void ErrorIfCoordinatorMetadataSetFalse(WorkerNode *workerNode, Datum val
 											   char *field);
 static WorkerNode * SetShouldHaveShards(WorkerNode *workerNode, bool shouldHaveShards);
 static void RemoveOldShardPlacementForNodeGroup(int groupId);
+static int FindCoordinatorNodeId(void);
 
 /* declarations for dynamic loading */
 PG_FUNCTION_INFO_V1(citus_set_coordinator_host);
@@ -148,6 +149,7 @@ PG_FUNCTION_INFO_V1(master_update_node);
 PG_FUNCTION_INFO_V1(get_shard_id_for_distribution_column);
 PG_FUNCTION_INFO_V1(citus_nodename_for_nodeid);
 PG_FUNCTION_INFO_V1(citus_nodeport_for_nodeid);
+PG_FUNCTION_INFO_V1(citus_coordinator_nodeid);
 
 
 /*
@@ -1537,6 +1539,25 @@ citus_nodeport_for_nodeid(PG_FUNCTION_ARGS)
 }
 
 
+/*
+ * citus_coordinator_nodeid returns the node id of the coordinator node
+ */
+Datum
+citus_coordinator_nodeid(PG_FUNCTION_ARGS)
+{
+	CheckCitusVersion(ERROR);
+
+	int coordinatorNodeId = FindCoordinatorNodeId();
+
+	if (coordinatorNodeId == -1)
+	{
+		PG_RETURN_INT32(0);
+	}
+
+	PG_RETURN_INT32(coordinatorNodeId);
+}
+
+
 /*
  * FindWorkerNode searches over the worker nodes and returns the workerNode
  * if it already exists. Else, the function returns NULL.
@@ -1635,6 +1656,28 @@ FindNodeWithNodeId(int nodeId, bool missingOk)
 }
 
 
+/*
+ * FindCoordinatorNodeId returns the node id of the coordinator node
+ */
+static int
+FindCoordinatorNodeId()
+{
+	bool includeNodesFromOtherClusters = false;
+	List *nodeList = ReadDistNode(includeNodesFromOtherClusters);
+	WorkerNode *node = NULL;
+
+	foreach_ptr(node, nodeList)
+	{
+		if (NodeIsCoordinator(node))
+		{
+			return node->nodeId;
+		}
+	}
+
+	return -1;
+}
+
+
 /*
  * ReadDistNode iterates over pg_dist_node table, converts each row
  * into it's memory representation (i.e., WorkerNode) and adds them into

src/backend/distributed/sql/citus--10.2-4--11.0-1.sql

@@ -103,3 +103,5 @@ GRANT SELECT ON pg_catalog.pg_dist_object TO public;
 
 #include "udfs/citus_nodeid_for_gpid/11.0-1.sql"
 #include "udfs/citus_pid_for_gpid/11.0-1.sql"
+
+#include "udfs/citus_coordinator_nodeid/11.0-1.sql"

src/backend/distributed/sql/downgrades/citus--11.0-1--10.2-4.sql

@@ -370,3 +370,5 @@ DROP FUNCTION pg_catalog.citus_nodeport_for_nodeid(integer);
 
 DROP FUNCTION pg_catalog.citus_nodeid_for_gpid(bigint);
 DROP FUNCTION pg_catalog.citus_pid_for_gpid(bigint);
+
+DROP FUNCTION pg_catalog.citus_coordinator_nodeid();

src/backend/distributed/sql/udfs/citus_coordinator_nodeid/11.0-1.sql

@@ -0,0 +1,7 @@
+CREATE OR REPLACE FUNCTION pg_catalog.citus_coordinator_nodeid()
+    RETURNS integer
+    LANGUAGE C STABLE STRICT
+    AS 'MODULE_PATHNAME', $$citus_coordinator_nodeid$$;
+
+COMMENT ON FUNCTION pg_catalog.citus_coordinator_nodeid()
+    IS 'returns node id of the coordinator node';

src/backend/distributed/sql/udfs/citus_coordinator_nodeid/latest.sql

@@ -0,0 +1,7 @@
+CREATE OR REPLACE FUNCTION pg_catalog.citus_coordinator_nodeid()
+    RETURNS integer
+    LANGUAGE C STABLE STRICT
+    AS 'MODULE_PATHNAME', $$citus_coordinator_nodeid$$;
+
+COMMENT ON FUNCTION pg_catalog.citus_coordinator_nodeid()
+    IS 'returns node id of the coordinator node';

src/test/regress/expected/global_cancel.out

@@ -62,10 +62,9 @@ CONTEXT:  while executing command on localhost:xxxxx
 SELECT pg_cancel_backend(citus_backend_gpid());
 ERROR:  canceling statement due to user request
 \c - postgres - :master_port
-SELECT nodeid AS coordinator_node_id FROM pg_dist_node WHERE nodeport = :master_port \gset
 SET client_min_messages TO DEBUG;
 -- 10000000000 is the node id multiplier for global pid
-SELECT pg_cancel_backend(10000000000 * :coordinator_node_id + 0);
+SELECT pg_cancel_backend(10000000000 * citus_coordinator_nodeid() + 0);
 DEBUG:  PID 0 is not a PostgreSQL server process
 DETAIL:  from localhost:xxxxx
  pg_cancel_backend
@@ -73,7 +72,7 @@ DETAIL:  from localhost:xxxxx
  f
 (1 row)
 
-SELECT pg_terminate_backend(10000000000 * :coordinator_node_id + 0);
+SELECT pg_terminate_backend(10000000000 * citus_coordinator_nodeid() + 0);
 DEBUG:  PID 0 is not a PostgreSQL server process
 DETAIL:  from localhost:xxxxx
  pg_terminate_backend
@@ -82,7 +81,7 @@ DETAIL:  from localhost:xxxxx
 (1 row)
 
 RESET client_min_messages;
-SELECT citus_backend_gpid() = citus_calculate_gpid(:coordinator_node_id, pg_backend_pid());
+SELECT citus_backend_gpid() = citus_calculate_gpid(citus_coordinator_nodeid(), pg_backend_pid());
  ?column?
 ---------------------------------------------------------------------
  t

src/test/regress/expected/multi_extension.out

@@ -1002,6 +1002,7 @@ SELECT * FROM multi_extension.print_extension_changes();
                                                                                                                       | function citus_calculate_gpid(integer,integer) bigint
                                                                                                                       | function citus_check_cluster_node_health() SETOF record
                                                                                                                       | function citus_check_connection_to_node(text,integer) boolean
+                                                                                                                      | function citus_coordinator_nodeid() integer
                                                                                                                       | function citus_disable_node(text,integer,boolean) void
                                                                                                                       | function citus_finalize_upgrade_to_citus11(boolean) boolean
                                                                                                                       | function citus_internal_add_colocation_metadata(integer,integer,integer,regtype,oid) void
@@ -1028,7 +1029,7 @@ SELECT * FROM multi_extension.print_extension_changes();
                                                                                                                       | function worker_partition_query_result(text,text,integer,citus.distribution_type,text[],text[],boolean,boolean,boolean) SETOF record
                                                                                                                       | table pg_dist_object
                                                                                                                       | view citus_stat_activity
-(40 rows)
+(41 rows)
 
 DROP TABLE multi_extension.prev_objects, multi_extension.extension_diff;
 -- show running version

src/test/regress/expected/upgrade_list_citus_objects.out

@@ -44,6 +44,7 @@ ORDER BY 1;
  function citus_check_connection_to_node(text,integer)
  function citus_cleanup_orphaned_shards()
  function citus_conninfo_cache_invalidate()
+ function citus_coordinator_nodeid()
  function citus_copy_shard_placement(bigint,text,integer,text,integer,boolean,citus.shard_transfer_mode)
  function citus_create_restore_point(text)
  function citus_disable_node(text,integer,boolean)
@@ -282,5 +283,5 @@ ORDER BY 1;
  view citus_stat_statements
  view pg_dist_shard_placement
  view time_partitions
-(266 rows)
+(267 rows)
 

src/test/regress/sql/global_cancel.sql

@@ -41,17 +41,15 @@ SELECT pg_cancel_backend(citus_backend_gpid());
 
 \c - postgres - :master_port
 
-SELECT nodeid AS coordinator_node_id FROM pg_dist_node WHERE nodeport = :master_port \gset
-
 SET client_min_messages TO DEBUG;
 
 -- 10000000000 is the node id multiplier for global pid
-SELECT pg_cancel_backend(10000000000 * :coordinator_node_id + 0);
+SELECT pg_cancel_backend(10000000000 * citus_coordinator_nodeid() + 0);
-SELECT pg_terminate_backend(10000000000 * :coordinator_node_id + 0);
+SELECT pg_terminate_backend(10000000000 * citus_coordinator_nodeid() + 0);
 
 RESET client_min_messages;
 
-SELECT citus_backend_gpid() = citus_calculate_gpid(:coordinator_node_id, pg_backend_pid());
+SELECT citus_backend_gpid() = citus_calculate_gpid(citus_coordinator_nodeid(), pg_backend_pid());
 
 SELECT nodename = citus_nodename_for_nodeid(nodeid) AND nodeport = citus_nodeport_for_nodeid(nodeid)
 FROM pg_dist_node