add_column :user_roles, :granter_id, :bigint
UserRole.update_all("granter_id = user_id")
change_column :user_roles, :granter_id, :bigint, :null => false
add_column :user_roles, :granter_id, :bigint
UserRole.update_all("granter_id = user_id")
change_column :user_roles, :granter_id, :bigint, :null => false