old_contents: #
  # 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.
  
  """Add ``root_dag_id`` to ``DAG``
  
  Revision ID: b3b105409875
  Revises: d38e04c12aa2
  Create Date: 2019-09-28 23:20:01.744775
  
  """
  
  import sqlalchemy as sa
  from alembic import op
  
  # revision identifiers, used by Alembic.
  revision = 'b3b105409875'
  down_revision = 'd38e04c12aa2'
  branch_labels = None
  depends_on = None
  airflow_version = '1.10.7'
  
  
  def upgrade():
      """Apply Add ``root_dag_id`` to ``DAG``"""
      op.add_column('dag', sa.Column('root_dag_id', sa.String(length=250), nullable=True))
      op.create_index('idx_root_dag_id', 'dag', ['root_dag_id'], unique=False)
  
  
  def downgrade():
      """Unapply Add ``root_dag_id`` to ``DAG``"""
      op.drop_index('idx_root_dag_id', table_name='dag')
      op.drop_column('dag', 'root_dag_id')
  
new_contents: #
  # 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.
  
  """Add ``root_dag_id`` to ``DAG``
  
  Revision ID: b3b105409875
  Revises: d38e04c12aa2
  Create Date: 2019-09-28 23:20:01.744775
  
  """
  
  import sqlalchemy as sa
  from alembic import op
  
  from airflow.migrations.db_types import StringID
  
  # revision identifiers, used by Alembic.
  revision = 'b3b105409875'
  down_revision = 'd38e04c12aa2'
  branch_labels = None
  depends_on = None
  airflow_version = '1.10.7'
  
  
  def upgrade():
      """Apply Add ``root_dag_id`` to ``DAG``"""
      op.add_column('dag', sa.Column('root_dag_id', StringID(), nullable=True))
      op.create_index('idx_root_dag_id', 'dag', ['root_dag_id'], unique=False)
  
  
  def downgrade():
      """Unapply Add ``root_dag_id`` to ``DAG``"""
      op.drop_index('idx_root_dag_id', table_name='dag')
      op.drop_column('dag', 'root_dag_id')
  
subject: Apply specific ID collation to root_dag_id too (#23536)