Remove unused index idx_last_scheduling_decision on dag_run table

airflow/migrations/versions/0069_2_0_0_add_scheduling_decision_to_dagrun_and_.py

@@ -48,7 +48,9 @@ def upgrade():
 
     with op.batch_alter_table("dag_run", schema=None) as batch_op:
         batch_op.add_column(sa.Column("last_scheduling_decision", TIMESTAMP, nullable=True))
-        batch_op.create_index("idx_last_scheduling_decision", ["last_scheduling_decision"], unique=False)
+        # Earlier we had here an index created on the last_scheduling_decision column.
+        # But we don't add it anymore since it's not useful.
+
         batch_op.add_column(sa.Column("dag_hash", sa.String(32), nullable=True))
 
     with op.batch_alter_table("dag", schema=None) as batch_op:
@@ -95,8 +97,14 @@ def downgrade():
     if is_sqlite:
         op.execute("PRAGMA foreign_keys=off")
 
+    # At 2.9.1 we removed idx_last_scheduling_decision index as it is not used, and changed this migration
+    # not to add it. So we use drop if exists (because it might not be there)
+    from contextlib import suppress
+
+    with suppress(sa.exc.DatabaseError):  # mysql does not support drop if exists index
+        op.drop_index("idx_last_scheduling_decision", table_name="dag_run", if_exists=True)
+
     with op.batch_alter_table("dag_run", schema=None) as batch_op:
-        batch_op.drop_index("idx_last_scheduling_decision")
         batch_op.drop_column("last_scheduling_decision")
         batch_op.drop_column("dag_hash")
 

airflow/migrations/versions/0142_2_9_1_remove_idx_last_scheduling_decision_.py

@@ -0,0 +1,50 @@
+#
+# 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.
+
+"""Remove idx_last_scheduling_decision index on last_scheduling_decision in dag_run table
+
+Revision ID: bff083ad727d
+Revises: 677fdbb7fc54
+Create Date: 2024-04-26 12:58:00.594762
+
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+
+# revision identifiers, used by Alembic.
+revision = 'bff083ad727d'
+down_revision = '677fdbb7fc54'
+branch_labels = None
+depends_on = None
+airflow_version = "2.9.1"
+
+
+def upgrade():
+    """Apply Remove idx_last_scheduling_decision index on last_scheduling_decision in dag_run table"""
+    # This index may have been created in 2.0.0, but we've since removed it from migrations
+    from contextlib import suppress
+
+    with suppress(sa.exc.DatabaseError):  # mysql does not support drop if exists index
+        op.drop_index("idx_last_scheduling_decision", table_name="dag_run", if_exists=True)
+
+
+def downgrade():
+    """Unapply Remove idx_last_scheduling_decision index on last_scheduling_decision in dag_run table"""
+    pass

airflow/models/dagrun.py

@@ -159,7 +159,6 @@ class DagRun(Base, LoggingMixin):
         Index("dag_id_state", dag_id, _state),
         UniqueConstraint("dag_id", "execution_date", name="dag_run_dag_id_execution_date_key"),
         UniqueConstraint("dag_id", "run_id", name="dag_run_dag_id_run_id_key"),
-        Index("idx_last_scheduling_decision", last_scheduling_decision),
         Index("idx_dag_run_dag_id", dag_id),
         Index(
             "idx_dag_run_running_dags",

docs/apache-airflow/img/airflow_erd.sha256

@@ -1 +1 @@
-77757e21aee500cb7fe7fd75e0f158633a0037d4d74e6f45eb14238f901ebacd
+7d4476fcd1b0d32102dea401db1baaf9d32130beeff82aff13c0b01bad3e0fcf

docs/apache-airflow/migrations-ref.rst

@@ -39,7 +39,10 @@ Here's the list of all the Database Migrations that are executed via when you ru
 +---------------------------------+-------------------+-------------------+--------------------------------------------------------------+
 | Revision ID                     | Revises ID        | Airflow Version   | Description                                                  |
 +=================================+===================+===================+==============================================================+
-| ``677fdbb7fc54`` (head)         | ``1949afb29106``  | ``2.10.0``        | add new executor field to db                                 |
+| ``bff083ad727d`` (head)         | ``677fdbb7fc54``  | ``2.9.1``         | Remove idx_last_scheduling_decision index on                 |
+|                                 |                   |                   | last_scheduling_decision in dag_run table                    |
++---------------------------------+-------------------+-------------------+--------------------------------------------------------------+
+| ``677fdbb7fc54``                | ``1949afb29106``  | ``2.10.0``        | add new executor field to db                                 |
 +---------------------------------+-------------------+-------------------+--------------------------------------------------------------+
 | ``1949afb29106``                | ``ee1467d4aa35``  | ``2.9.0``         | update trigger kwargs type and encrypt                       |
 +---------------------------------+-------------------+-------------------+--------------------------------------------------------------+