如何删除airflow中不再使用的dag

如上图，airflow中的dag关闭后仍然会在webui中占坑，实在碍眼。调研后发现airflow并未提供删除功能。

经分析实践，可以通过删除airflow的元数据库中相应数据，从而达到删除dag的目的。

接上图，要删除dag squaredance_datamart，需要删除元数据库中如下表的相应数据：

select count(1) from dag                where dag_id='squaredance_datamart';
select count(1) from dag_run            where dag_id='squaredance_datamart';
select count(1) from dag_stats          where dag_id='squaredance_datamart';
select count(1) from job                where dag_id='squaredance_datamart';
select count(1) from log                where dag_id='squaredance_datamart';
select count(1) from sla_miss           where dag_id='squaredance_datamart';
select count(1) from task_fail          where dag_id='squaredance_datamart';
select count(1) from task_instance      where dag_id='squaredance_datamart';
select count(1) from xcom               where dag_id='squaredance_datamart';               

delete from dag                where dag_id='squaredance_datamart';
delete from dag_run            where dag_id='squaredance_datamart';
delete from dag_stats          where dag_id='squaredance_datamart';
delete from job                where dag_id='squaredance_datamart';
delete from log                where dag_id='squaredance_datamart';
delete from sla_miss           where dag_id='squaredance_datamart';
delete from task_fail          where dag_id='squaredance_datamart';
delete from task_instance      where dag_id='squaredance_datamart';
delete from xcom               where dag_id='squaredance_datamart';