diff --git a/airflow/hooks/hive_hook.py b/airflow/hooks/hive_hook.py
index d36c3e09e1..0b5503d501 100644
--- a/airflow/hooks/hive_hook.py
+++ b/airflow/hooks/hive_hook.py
@@ -45,7 +45,7 @@ class HiveHook(BaseHook):
 
     def __setstate__(self, d):
         self.__dict__.update(d)
-        d['hive'] = self.get_hive_client()
+        self.__dict__['hive'] = self.get_hive_client()
 
     def get_hive_client(self):
         transport = TSocket.TSocket(self.host, self.port)
@@ -61,7 +61,7 @@ class HiveHook(BaseHook):
             self.hive._oprot.trans.open()
             partitions = self.hive.get_partitions_by_filter(
                 schema, table, partition, 1)
-            self.transport.close()
+            self.hive._oprot.trans.close()
             if partitions:
                 return True
             else:
diff --git a/airflow/models.py b/airflow/models.py
index 41c10a23b9..ebc3262add 100644
--- a/airflow/models.py
+++ b/airflow/models.py
@@ -864,10 +864,11 @@ class BaseOperator(Base):
     def __repr__(self):
         return "<Task({self.task_type}): {self.task_id}>".format(self=self)
 
-    @staticmethod
-    def append_only_new(l, item):
+    def append_only_new(self, l, item):
         if item in l:
-            raise Exception('Dependency already registered')
+            raise Exception(
+                'Dependency {self}, {item} already registered'
+                ''.format(**locals()))
         else:
             l.append(item)
 
@@ -921,7 +922,7 @@ class DAG(Base):
     full_filepath = Column(String(2000))
 
     tasks = relationship(
-        "BaseOperator", cascade="merge, delete, delete-orphan", backref='dag')
+        "BaseOperator", cascade="all, delete-orphan", backref='dag')
 
     def __init__(
             self, dag_id,
@@ -1061,6 +1062,7 @@ class DAG(Base):
         for task in self.tasks:
             if task.task_id == task_id:
                 return task
+        raise Exception("Task {task_id} not found".format(**locals()))
 
     def tree_view(self):
         """
@@ -1085,6 +1087,10 @@ class DAG(Base):
             task.dag = self
         self.task_count = len(self.tasks)
 
+    def add_tasks(self, tasks):
+        for task in tasks:
+            self.add_task(task)
+
     def db_merge(self):
         session = settings.Session()
         session.merge(self)
diff --git a/airflow/operators/sensors.py b/airflow/operators/sensors.py
index 0a39da0281..8eb7558465 100644
--- a/airflow/operators/sensors.py
+++ b/airflow/operators/sensors.py
@@ -118,11 +118,13 @@ class HivePartitionSensor(BaseSensorOperator):
 
     def __init__(
             self,
-            table, partition,
+            table, partition="ds='{{ ds }}'",
             hive_dbid=getconf().get('hooks', 'HIVE_DEFAULT_DBID'),
             schema='default',
             *args, **kwargs):
         super(HivePartitionSensor, self).__init__(*args, **kwargs)
+        if '.' in table:
+            schema, table = table.split('.')
         self.hive_dbid = hive_dbid
         self.hook = HiveHook(hive_dbid=hive_dbid)
         self.table = table
@@ -131,7 +133,7 @@ class HivePartitionSensor(BaseSensorOperator):
 
     def poke(self):
         logging.info(
-            'Poking for table {self.table}, '
+            'Poking for table {self.schema}{self.table}, '
             'partition {self.partition}'.format(**locals()))
         return self.hook.check_for_partition(
             self.schema, self.table, self.partition)