**** CubicPower OpenStack Study ****
def upgrade(migrate_engine):
"""Add _name_id column to volumes."""
meta = MetaData()
meta.bind = migrate_engine
volumes = Table('volumes', meta, autoload=True)
_name_id = Column('_name_id', String(36))
volumes.create_column(_name_id)
volumes.update().values(_name_id=None).execute()
**** CubicPower OpenStack Study ****
def downgrade(migrate_engine):
"""Remove _name_id column from volumes."""
meta = MetaData()
meta.bind = migrate_engine
volumes = Table('volumes', meta, autoload=True)
_name_id = volumes.columns._name_id
volumes.drop_column(_name_id)