如何刪除airflow中不再使用的dag

如上圖，airflow中的dag關閉後仍然會在webui中佔坑，實在礙眼。調研後發現airflow並未提供刪除功能。

經分析實踐，可以通過刪除airflow的元數據庫中相應數據，從而達到刪除dag的目的。

接上圖，要刪除dag squaredance_datamart，需要刪除元數據庫中如下表的相應數據：

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';