Fix slow DAG deletion due to missing dag_id index for job table (#…

…20282)

Fixes #20249

airflow/jobs/base_job.py

@@ -71,6 +71,7 @@ class BaseJob(Base, LoggingMixin):
     __table_args__ = (
         Index('job_type_heart', job_type, latest_heartbeat),
         Index('idx_job_state_heartbeat', state, latest_heartbeat),
+        Index('idx_job_dag_id', dag_id),
     )
 
     task_instances_enqueued = relationship(

airflow/migrations/versions/587bdf053233_adding_index_for_dag_id_in_job.py

@@ -0,0 +1,43 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+"""adding index for dag_id in job
+
+Revision ID: 587bdf053233
+Revises: f9da662e7089
+Create Date: 2021-12-14 10:20:12.482940
+
+"""
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = '587bdf053233'
+down_revision = 'f9da662e7089'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    """Apply adding index for dag_id in job"""
+    op.create_index('idx_job_dag_id', 'job', ['dag_id'], unique=False)
+
+
+def downgrade():
+    """Unapply adding index for dag_id in job"""
+    op.drop_index('idx_job_dag_id', table_name='job')

docs/apache-airflow/migrations-ref.rst

@@ -23,8 +23,9 @@ Here's the list of all the Database Migrations that are executed via when you ru
 +--------------------------------+------------------+-----------------+---------------------------------------------------------------------------------------+
 | Revision ID                    | Revises ID       | Airflow Version | Description                                                                           |
 +--------------------------------+------------------+-----------------+---------------------------------------------------------------------------------------+
-| ``f9da662e7089`` (head)        | ``786e3737b18f`` | ``2.3.0``       | Add ``LogTemplate`` table to track changes to config values ``log_filename_template`` |
-|                                |                  |                 | and ``task_log_prefix_template``.                                                     |
+| ``587bdf053233`` (head)        | ``f9da662e7089`` | ``2.3.0``       | Add index for ``dag_id`` column in ``job`` table.                                     |
++--------------------------------+------------------+-----------------+---------------------------------------------------------------------------------------+
+| ``f9da662e7089``               | ``786e3737b18f`` | ``2.3.0``       | Add ``LogTemplate`` table to track changes to config values ``log_filename_template`` |
 +--------------------------------+------------------+-----------------+---------------------------------------------------------------------------------------+
 | ``786e3737b18f``               | ``5e3ec427fdd3`` | ``2.3.0``       | Add ``timetable_description`` column to DagModel for UI.                              |
 +--------------------------------+------------------+-----------------+---------------------------------------------------------------------------------------+