use ActiveReadableNodeList in JobExecutorType and task tracker

The reason we should use ActiveReadableNodeList instead of ActiveReadableNonCoordinatorNodeList is that if coordinator is added to cluster as a worker, it should be counted as well. Otherwise if there is only coordinator in the cluster, the count will be 0, hence we get a warning.

In MultiTaskTrackerExecute, we should connect to coordinator if it is
added to the cluster because it will also be assigned tasks.

src/backend/distributed/executor/multi_server_executor.c

@@ -118,8 +118,7 @@ JobExecutorType(DistributedPlan *distributedPlan)
 	}
 	else
 	{
-		List *workerNodeList = ActiveReadableNonCoordinatorNodeList();
-		int workerNodeCount = list_length(workerNodeList);
+		int workerNodeCount = list_length(ActiveReadableNodeList());
 		int taskCount = list_length(job->taskList);
 		double tasksPerNode = taskCount / ((double) workerNodeCount);
 

src/backend/distributed/executor/multi_task_tracker_executor.c

@@ -209,7 +209,7 @@ MultiTaskTrackerExecute(Job *job)
 	 * assigning and checking the status of tasks. The second (temporary) hash
 	 * helps us in fetching results data from worker nodes to the master node.
 	 */
-	List *workerNodeList = ActivePrimaryNonCoordinatorNodeList(NoLock);
+	List *workerNodeList = ActiveReadableNodeList();
 	uint32 taskTrackerCount = (uint32) list_length(workerNodeList);
 
 	/* connect as the current user for running queries */

src/backend/distributed/operations/worker_node_manager.c

@@ -319,6 +319,7 @@ ActiveReadableNonCoordinatorNodeCount(void)
 	return liveWorkerCount;
 }
 
+
 /*
  * NodeIsCoordinator returns true if the given node represents the coordinator.
  */

src/test/regress/expected/single_node.out

@@ -231,6 +231,51 @@ SELECT count(*) FROM test WHERE false GROUP BY GROUPING SETS (x,y);
 (0 rows)
 
 RESET citus.task_assignment_policy;
+-- single node task tracker tests:
+SET citus.task_executor_type to 'task-tracker';
+SELECT count(*) FROM test;
+ count
+---------------------------------------------------------------------
+     5
+(1 row)
+
+-- INSERT SELECT from distributed table to local table
+BEGIN;
+INSERT INTO ref(a, b) SELECT x, y FROM test;
+SELECT count(*) from ref;
+ERROR:  cannot switch local execution status from local execution required to local execution disabled since it can cause visibility problems in the current transaction
+ROLLBACK;
+-- INSERT SELECT from distributed table to local table
+BEGIN;
+INSERT INTO ref(a, b) SELECT c, d FROM local;
+SELECT count(*) from ref;
+ count
+---------------------------------------------------------------------
+     6
+(1 row)
+
+ROLLBACK;
+-- INSERT SELECT from distributed table to local table
+BEGIN;
+INSERT INTO local(c, d) SELECT x, y FROM test;
+SELECT count(*) from local;
+ count
+---------------------------------------------------------------------
+     8
+(1 row)
+
+ROLLBACK;
+-- INSERT SELECT from distributed table to local table
+BEGIN;
+INSERT INTO local(c, d) SELECT a, b FROM ref;
+SELECT count(*) from local;
+ count
+---------------------------------------------------------------------
+     6
+(1 row)
+
+ROLLBACK;
+RESET citus.task_executor_type;
 -- Cleanup
 SET client_min_messages TO WARNING;
 DROP SCHEMA single_node CASCADE;

src/test/regress/sql/single_node.sql

@@ -102,6 +102,35 @@ SELECT count(*) FROM test WHERE false;
 SELECT count(*) FROM test WHERE false GROUP BY GROUPING SETS (x,y);
 RESET citus.task_assignment_policy;
 
+-- single node task tracker tests:
+SET citus.task_executor_type to 'task-tracker';
+SELECT count(*) FROM test;
+
+-- INSERT SELECT from distributed table to local table
+BEGIN;
+INSERT INTO ref(a, b) SELECT x, y FROM test;
+SELECT count(*) from ref;
+ROLLBACK;
+
+-- INSERT SELECT from distributed table to local table
+BEGIN;
+INSERT INTO ref(a, b) SELECT c, d FROM local;
+SELECT count(*) from ref;
+ROLLBACK;
+
+-- INSERT SELECT from distributed table to local table
+BEGIN;
+INSERT INTO local(c, d) SELECT x, y FROM test;
+SELECT count(*) from local;
+ROLLBACK;
+
+-- INSERT SELECT from distributed table to local table
+BEGIN;
+INSERT INTO local(c, d) SELECT a, b FROM ref;
+SELECT count(*) from local;
+ROLLBACK;
+
+RESET citus.task_executor_type;
 
 -- Cleanup
 SET client_min_messages TO WARNING;