[AIRFLOW-3627] Refine performance of /task_stats (#4433)

airflow/www/views.py

@@ -594,21 +594,24 @@ class Airflow(BaseView):
         dag_ids = session.query(Dag.dag_id)
 
         LastDagRun = (
-            session.query(DagRun.dag_id, sqla.func.max(DagRun.execution_date).label('execution_date'))
-                .join(Dag, Dag.dag_id == DagRun.dag_id)
-                .filter(DagRun.state != State.RUNNING)
-                .filter(Dag.is_active == True)  # noqa: E712
-                .filter(Dag.is_subdag == False)  # noqa: E712
-                .group_by(DagRun.dag_id)
-                .subquery('last_dag_run')
+            session.query(
+                DagRun.dag_id,
+                sqla.func.max(DagRun.execution_date).label('execution_date')
+            )
+            .join(Dag, Dag.dag_id == DagRun.dag_id)
+            .filter(DagRun.state != State.RUNNING,
+                    Dag.is_active,
+                    Dag.is_subdag == False)  # noqa: E712
+            .group_by(DagRun.dag_id)
+            .subquery('last_dag_run')
         )
         RunningDagRun = (
             session.query(DagRun.dag_id, DagRun.execution_date)
-                .join(Dag, Dag.dag_id == DagRun.dag_id)
-                .filter(DagRun.state == State.RUNNING)
-                .filter(Dag.is_active == True)  # noqa: E712
-                .filter(Dag.is_subdag == False)  # noqa: E712
-                .subquery('running_dag_run')
+            .join(Dag, Dag.dag_id == DagRun.dag_id)
+            .filter(DagRun.state == State.RUNNING,
+                    Dag.is_active,
+                    Dag.is_subdag == False)  # noqa: E712
+            .subquery('running_dag_run')
         )
 
         # Select all task_instances from active dag_runs.

airflow/www_rbac/views.py

@@ -337,19 +337,18 @@ class Airflow(AirflowBaseView):
 
         LastDagRun = (
             session.query(
-                        DagRun.dag_id,
-                        sqla.func.max(DagRun.execution_date).label('execution_date'))
-                   .join(Dag, Dag.dag_id == DagRun.dag_id)
-                   .filter(DagRun.state != State.RUNNING)
-                   .filter(Dag.is_active == True)  # noqa
-                   .group_by(DagRun.dag_id)
-                   .subquery('last_dag_run')
+                DagRun.dag_id,
+                sqla.func.max(DagRun.execution_date).label('execution_date')
+            )
+            .join(Dag, Dag.dag_id == DagRun.dag_id)
+            .filter(DagRun.state != State.RUNNING, Dag.is_active)
+            .group_by(DagRun.dag_id)
+            .subquery('last_dag_run')
         )
         RunningDagRun = (
             session.query(DagRun.dag_id, DagRun.execution_date)
                    .join(Dag, Dag.dag_id == DagRun.dag_id)
-                   .filter(DagRun.state == State.RUNNING)
-                   .filter(Dag.is_active == True)  # noqa
+                   .filter(DagRun.state == State.RUNNING, Dag.is_active)
                    .subquery('running_dag_run')
         )
 
@@ -1407,7 +1406,7 @@ class Airflow(AirflowBaseView):
         TF = models.TaskFail
         ti_fails = (
             session.query(TF)
-                   .filter(TF.dag_id == dag.dag_id,  # noqa
+                   .filter(TF.dag_id == dag.dag_id,
                            TF.execution_date >= min_date,
                            TF.execution_date <= base_date,
                            TF.task_id.in_([t.task_id for t in dag.tasks]))