text: # Copyright 2012 OpenStack Foundation
  #
  #    Licensed 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.
  
  from sqlalchemy import String, Column, MetaData, Table, delete
  
  
  def upgrade(migrate_engine):
      meta = MetaData()
      meta.bind = migrate_engine
  
      aggregates = Table('aggregates', meta, autoload=True)
      aggregate_metadata = Table('aggregate_metadata', meta, autoload=True)
      # migrate data
      record_list = list(aggregates.select().execute())
      for rec in record_list:
          row = aggregate_metadata.insert()
          row.execute({'created_at': rec['created_at'],
                      'updated_at': rec['updated_at'],
                      'deleted_at': rec['deleted_at'],
                      'deleted': rec['deleted'],
                      'key': 'availability_zone',
                      'value': rec['availability_zone'],
                      'aggregate_id': rec['id'],
                      })
      aggregates.drop_column('availability_zone')
  
  
  def downgrade(migrate_engine):
      meta = MetaData()
      meta.bind = migrate_engine
  
      aggregates = Table('aggregates', meta, autoload=True)
      aggregate_metadata = Table('aggregate_metadata', meta, autoload=True)
      availability_zone = Column('availability_zone', String(255))
      aggregates.create_column(availability_zone)
  
      # Migrate data back
      # NOTE(jhesketh): This needs to be done with individual inserts as multiple
      # results in an update sub-query do not work with MySQL. See bug/1207956.
      record_list = list(aggregates.select().execute())
      for rec in record_list:
          result = aggregate_metadata.select().where(
              aggregate_metadata.c.key == 'availability_zone'
          ).where(
              aggregate_metadata.c.aggregate_id == rec['id']
          )
  
          aggregates.update().values(
              availability_zone=list(result.execute())[0]['value']
          ).where(
              aggregates.c.id == rec['id']
          ).execute()
  
      delete(aggregate_metadata,
             aggregate_metadata.c.key == 'availability_zone').execute()
      aggregates.c.availability_zone.alter(nullable=False)
  