Make sure that TRUNCATE always opens a DDL access

src/backend/distributed/executor/multi_router_executor.c

@@ -1316,17 +1316,14 @@ ExecuteModifyTasks(List *taskList, bool expectResults, ParamListInfo paramListIn
 
 	/*
 	 * Ensure that there are no concurrent modifications on the same
-	 * shards. For DDL commands, we already obtained the appropriate
+	 * shards. In general, for DDL commands, we already obtained the
-	 * locks in ProcessUtility.
+	 * appropriate locks in ProcessUtility. However, we still prefer to
-	 *
+	 * acquire the executor locks for DDLs specifically for TRUNCATE
-	 * We don't need to acquire lock for TRUNCATE_TASK since it already
+	 * command on a partition table since AcquireExecutorMultiShardLocks()
-	 * acquires AccessExclusiveLock on the relation, and blocks any
+	 * ensures that no concurrent modifications happens on the parent
-	 * concurrent operation.
+	 * tables.
 	 */
-	if (firstTask->taskType == MODIFY_TASK)
-	{
 	AcquireExecutorMultiShardLocks(taskList);
-	}
 
 	BeginOrContinueCoordinatedTransaction();
 

src/backend/distributed/master/master_modify_multiple_shards.c

@@ -55,7 +55,8 @@
 #include "utils/memutils.h"
 
 
-static List * ModifyMultipleShardsTaskList(Query *query, List *shardIntervalList);
+static List * ModifyMultipleShardsTaskList(Query *query, List *shardIntervalList, TaskType
+										   taskType);
 
 
 PG_FUNCTION_INFO_V1(master_modify_multiple_shards);
@@ -85,6 +86,7 @@ master_modify_multiple_shards(PG_FUNCTION_ARGS)
 	List *taskList = NIL;
 	int32 affectedTupleCount = 0;
 	CmdType operation = CMD_UNKNOWN;
+	TaskType taskType = TASK_TYPE_INVALID_FIRST;
 #if (PG_VERSION_NUM >= 100000)
 	RawStmt *rawStmt = (RawStmt *) ParseTreeRawStmt(queryString);
 	queryTreeNode = rawStmt->stmt;
@@ -159,6 +161,12 @@ master_modify_multiple_shards(PG_FUNCTION_ARGS)
 		{
 			RaiseDeferredError(error, ERROR);
 		}
+
+		taskType = MODIFY_TASK;
+	}
+	else
+	{
+		taskType = DDL_TASK;
 	}
 
 	/* reject queries with a returning list */
@@ -179,7 +187,7 @@ master_modify_multiple_shards(PG_FUNCTION_ARGS)
 	CHECK_FOR_INTERRUPTS();
 
 	taskList =
-		ModifyMultipleShardsTaskList(modifyQuery, prunedShardIntervalList);
+		ModifyMultipleShardsTaskList(modifyQuery, prunedShardIntervalList, taskType);
 
 	if (MultiShardConnectionType == SEQUENTIAL_CONNECTION)
 	{
@@ -200,7 +208,7 @@ master_modify_multiple_shards(PG_FUNCTION_ARGS)
  * given list of shards.
  */
 static List *
-ModifyMultipleShardsTaskList(Query *query, List *shardIntervalList)
+ModifyMultipleShardsTaskList(Query *query, List *shardIntervalList, TaskType taskType)
 {
 	List *taskList = NIL;
 	ListCell *shardIntervalCell = NULL;
@@ -223,7 +231,7 @@ ModifyMultipleShardsTaskList(Query *query, List *shardIntervalList)
 		task = CitusMakeNode(Task);
 		task->jobId = jobId;
 		task->taskId = taskId++;
-		task->taskType = MODIFY_TASK;
+		task->taskType = taskType;
 		task->queryString = shardQueryString->data;
 		task->dependedTaskList = NULL;
 		task->replicationModel = REPLICATION_MODEL_INVALID;

src/test/regress/expected/multi_partitioning_0.out

@@ -1122,13 +1122,11 @@ SELECT relation::regclass, locktype, mode FROM pg_locks WHERE relation::regclass
  partitioning_locks      | relation | AccessShareLock
  partitioning_locks_2009 | relation | AccessExclusiveLock
  partitioning_locks_2009 | relation | AccessShareLock
- partitioning_locks_2009 | relation | RowExclusiveLock
  partitioning_locks_2009 | relation | ShareLock
  partitioning_locks_2010 | relation | AccessExclusiveLock
  partitioning_locks_2010 | relation | AccessShareLock
- partitioning_locks_2010 | relation | RowExclusiveLock
  partitioning_locks_2010 | relation | ShareLock
-(10 rows)
+(8 rows)
 
 COMMIT;
 -- test shard resource locks with master_modify_multiple_shards

src/test/regress/expected/relation_access_tracking.out

@@ -584,13 +584,34 @@ BEGIN;
 (2 rows)
 
 ROLLBACK;
--- FIXME: TRUNCATE should be DDL
+-- TRUNCATE should be DDL
 BEGIN;
 	TRUNCATE table_1;
 	SELECT * FROM relation_acesses  WHERE table_name IN ('table_1')  ORDER BY 1;
  table_name | select_access |  dml_access  |   ddl_access    
-------------+---------------+-----------------+--------------
+------------+---------------+--------------+-----------------
- table_1    | not_accessed  | parallel_access | not_accessed
+ table_1    | not_accessed  | not_accessed | parallel_access
+(1 row)
+
+ROLLBACK;
+-- TRUNCATE can be a sequential DDL
+BEGIN;
+	SET LOCAL citus.multi_shard_modify_mode = 'sequential';
+	TRUNCATE table_1;
+	SELECT * FROM relation_acesses  WHERE table_name IN ('table_1')  ORDER BY 1;
+ table_name | select_access |  dml_access  |    ddl_access     
+------------+---------------+--------------+-------------------
+ table_1    | not_accessed  | not_accessed | sequential_access
+(1 row)
+
+ROLLBACK;
+-- TRUNCATE on a reference table should be sequential
+BEGIN;
+	TRUNCATE table_6;
+	SELECT * FROM relation_acesses  WHERE table_name IN ('table_6')  ORDER BY 1;
+ table_name | select_access |  dml_access  |    ddl_access     
+------------+---------------+--------------+-------------------
+ table_6    | not_accessed  | not_accessed | sequential_access
 (1 row)
 
 ROLLBACK;
@@ -674,9 +695,9 @@ BEGIN;
 NOTICE:  truncate cascades to table "table_2"
 	SELECT * FROM relation_acesses  WHERE table_name IN ('table_1', 'table_2')  ORDER BY 1;
  table_name | select_access |  dml_access  |   ddl_access    
-------------+---------------+-----------------+--------------
+------------+---------------+--------------+-----------------
- table_1    | not_accessed  | parallel_access | not_accessed
+ table_1    | not_accessed  | not_accessed | parallel_access
- table_2    | not_accessed  | parallel_access | not_accessed
+ table_2    | not_accessed  | not_accessed | parallel_access
 (2 rows)
 
 ROLLBACK;

src/test/regress/sql/relation_access_tracking.sql

@@ -351,12 +351,25 @@ BEGIN;
 	SELECT * FROM relation_acesses  WHERE table_name IN ('table_6', 'table_1');
 ROLLBACK;
 
--- FIXME: TRUNCATE should be DDL
+-- TRUNCATE should be DDL
 BEGIN;
 	TRUNCATE table_1;
 	SELECT * FROM relation_acesses  WHERE table_name IN ('table_1')  ORDER BY 1;
 ROLLBACK;
 
+-- TRUNCATE can be a sequential DDL
+BEGIN;
+	SET LOCAL citus.multi_shard_modify_mode = 'sequential';
+	TRUNCATE table_1;
+	SELECT * FROM relation_acesses  WHERE table_name IN ('table_1')  ORDER BY 1;
+ROLLBACK;
+
+-- TRUNCATE on a reference table should be sequential
+BEGIN;
+	TRUNCATE table_6;
+	SELECT * FROM relation_acesses  WHERE table_name IN ('table_6')  ORDER BY 1;
+ROLLBACK;
+
 -- creating foreign keys should consider adding the placement accesses for the referenced table
 ALTER TABLE table_1 ADD CONSTRAINT table_1_u UNIQUE (key);
 BEGIN;