diff --git a/nova/cmd/status.py b/nova/cmd/status.py
index 1974feb58b0b..75ae63d07d97 100644
--- a/nova/cmd/status.py
+++ b/nova/cmd/status.py
@@ -25,8 +25,8 @@ from oslo_config import cfg
 from oslo_upgradecheck import common_checks
 from oslo_upgradecheck import upgradecheck
 import pkg_resources
+import sqlalchemy as sa
 from sqlalchemy import func as sqlfunc
-from sqlalchemy import MetaData, Table, select
 
 from nova.cmd import common as cmd_common
 import nova.conf
@@ -86,10 +86,10 @@ class UpgradeCommands(upgradecheck.UpgradeCommands):
         # table, or by only counting compute nodes with a service version of at
         # least 15 which was the highest service version when Newton was
         # released.
-        meta = MetaData(bind=db_session.get_engine(context=context))
-        compute_nodes = Table('compute_nodes', meta, autoload=True)
-        return select([sqlfunc.count()]).select_from(compute_nodes).where(
-                compute_nodes.c.deleted == 0).scalar()
+        meta = sa.MetaData(bind=db_session.get_engine(context=context))
+        compute_nodes = sa.Table('compute_nodes', meta, autoload=True)
+        return sa.select([sqlfunc.count()]).select_from(compute_nodes).where(
+            compute_nodes.c.deleted == 0).scalar()
 
     def _check_cellsv2(self):
         """Checks to see if cells v2 has been setup.
@@ -102,7 +102,7 @@ class UpgradeCommands(upgradecheck.UpgradeCommands):
         this on an initial install. This also has to be careful about checking
         for compute nodes if there are no host mappings on a fresh install.
         """
-        meta = MetaData()
+        meta = sa.MetaData()
         meta.bind = db_session.get_api_engine()
 
         cell_mappings = self._get_cell_mappings()
@@ -122,8 +122,9 @@ class UpgradeCommands(upgradecheck.UpgradeCommands):
                     'retry.')
             return upgradecheck.Result(upgradecheck.Code.FAILURE, msg)
 
-        host_mappings = Table('host_mappings', meta, autoload=True)
-        count = select([sqlfunc.count()]).select_from(host_mappings).scalar()
+        host_mappings = sa.Table('host_mappings', meta, autoload=True)
+        count = sa.select([sqlfunc.count()]).select_from(host_mappings)\
+            .scalar()
         if count == 0:
             # This may be a fresh install in which case there may not be any
             # compute_nodes in the cell database if the nova-compute service
diff --git a/nova/db/sqlalchemy/api.py b/nova/db/sqlalchemy/api.py
index c65dcdc2c952..816bcc63d47b 100644
--- a/nova/db/sqlalchemy/api.py
+++ b/nova/db/sqlalchemy/api.py
@@ -35,26 +35,12 @@ from oslo_utils import importutils
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
 import sqlalchemy as sa
-from sqlalchemy import and_
-from sqlalchemy import Boolean
-from sqlalchemy.exc import NoSuchTableError
-from sqlalchemy import Integer
-from sqlalchemy import MetaData
-from sqlalchemy import or_
-from sqlalchemy.orm import aliased
-from sqlalchemy.orm import joinedload
-from sqlalchemy.orm import noload
-from sqlalchemy.orm import subqueryload
-from sqlalchemy.orm import undefer
-from sqlalchemy.schema import Table
+from sqlalchemy import exc as sqla_exc
+from sqlalchemy import orm
+from sqlalchemy import schema
 from sqlalchemy import sql
-from sqlalchemy.sql.expression import asc
-from sqlalchemy.sql.expression import cast
-from sqlalchemy.sql.expression import desc
-from sqlalchemy.sql import false
+from sqlalchemy.sql import expression
 from sqlalchemy.sql import func
-from sqlalchemy.sql import null
-from sqlalchemy.sql import true
 
 from nova import block_device
 from nova.compute import task_states
@@ -94,7 +80,7 @@ def _context_manager_from_context(context):
 
 def _joinedload_all(column):
     elements = column.split('.')
-    joined = joinedload(elements.pop(0))
+    joined = orm.joinedload(elements.pop(0))
     for element in elements:
         joined = joined.joinedload(element)
 
@@ -293,9 +279,10 @@ def model_query(
     # us to return both our projects and unowned projects.
     if nova.context.is_user_context(context) and project_only:
         if project_only == 'allow_none':
-            query = query.\
-                filter(or_(model.project_id == context.project_id,
-                           model.project_id == null()))
+            query = query.filter(sql.or_(
+                model.project_id == context.project_id,
+                model.project_id == sql.null()
+            ))
         else:
             query = query.filter_by(project_id=context.project_id)
 
@@ -367,7 +354,7 @@ class EqualityCondition(object):
     def clauses(self, field):
         # method signature requires us to return an iterable even if for OR
         # operator this will actually be a single clause
-        return [or_(*[field == value for value in self.values])]
+        return [sql.or_(*[field == value for value in self.values])]
 
 
 class InequalityCondition(object):
@@ -395,9 +382,10 @@ def service_destroy(context, service_id):
         # TODO(sbauza): Remove the service_id filter in a later release
         # once we are sure that all compute nodes report the host field
         model_query(context, models.ComputeNode).\
-                    filter(or_(models.ComputeNode.service_id == service_id,
-                               models.ComputeNode.host == service['host'])).\
-                    soft_delete(synchronize_session=False)
+            filter(sql.or_(
+                models.ComputeNode.service_id == service_id,
+                models.ComputeNode.host == service['host'])).\
+            soft_delete(synchronize_session=False)
 
 
 @pick_context_manager_reader
@@ -434,7 +422,7 @@ def service_get_minimum_version(context, binaries):
         func.min(models.Service.version)).\
                          filter(models.Service.binary.in_(binaries)).\
                          filter(models.Service.deleted == 0).\
-                         filter(models.Service.forced_down == false()).\
+                         filter(models.Service.forced_down == sql.false()).\
                          group_by(models.Service.binary)
     return dict(min_versions)
 
@@ -615,7 +603,7 @@ def _compute_node_select(context, filters=None, limit=None, marker=None):
         select = select.limit(limit)
     # Explicitly order by id, so we're not dependent on the native sort
     # order of the underlying DB.
-    select = select.order_by(asc("id"))
+    select = select.order_by(expression.asc("id"))
     return select
 
 
@@ -921,7 +909,7 @@ def compute_node_statistics(context):
                 inner_sel.c.host == services_tbl.c.host,
                 inner_sel.c.service_id == services_tbl.c.id
             ),
-            services_tbl.c.disabled == false(),
+            services_tbl.c.disabled == sql.false(),
             services_tbl.c.binary == 'nova-compute',
             services_tbl.c.deleted == 0
         )
@@ -1106,9 +1094,9 @@ def virtual_interface_get_by_instance(context, instance_uuid):
     :param instance_uuid: UUID of the instance to filter on.
     """
     vif_refs = _virtual_interface_query(context).\
-                       filter_by(instance_uuid=instance_uuid).\
-                       order_by(asc("created_at"), asc("id")).\
-                       all()
+        filter_by(instance_uuid=instance_uuid).\
+        order_by(expression.asc("created_at"), expression.asc("id")).\
+        all()
     return vif_refs
 
 
@@ -1414,7 +1402,7 @@ def instance_get(context, instance_id, columns_to_join=None):
 def _build_instance_get(context, columns_to_join=None):
     query = model_query(context, models.Instance, project_only=True).\
             options(_joinedload_all('security_groups.rules')).\
-            options(joinedload('info_cache'))
+            options(orm.joinedload('info_cache'))
     if columns_to_join is None:
         columns_to_join = ['metadata', 'system_metadata']
     for column in columns_to_join:
@@ -1422,7 +1410,7 @@ def _build_instance_get(context, columns_to_join=None):
             # Already always joined above
             continue
         if 'extra.' in column:
-            query = query.options(undefer(column))
+            query = query.options(orm.undefer(column))
         elif column in ['metadata', 'system_metadata']:
             # NOTE(melwitt): We use subqueryload() instead of joinedload() for
             # metadata and system_metadata because of the one-to-many
@@ -1432,13 +1420,13 @@ def _build_instance_get(context, columns_to_join=None):
             # in a large data transfer. Instead, the subqueryload() will
             # perform additional queries to obtain metadata and system_metadata
             # for the instance.
-            query = query.options(subqueryload(column))
+            query = query.options(orm.subqueryload(column))
         else:
-            query = query.options(joinedload(column))
+            query = query.options(orm.joinedload(column))
     # NOTE(alaski) Stop lazy loading of columns not needed.
     for col in ['metadata', 'system_metadata']:
         if col not in columns_to_join:
-            query = query.options(noload(col))
+            query = query.options(orm.noload(col))
     # NOTE(melwitt): We need to use order_by(<unique column>) so that the
     # additional queries emitted by subqueryload() include the same ordering as
     # used by the parent query.
@@ -1531,7 +1519,7 @@ def instance_get_all(context, columns_to_join=None):
             _manual_join_columns(columns_to_join))
     query = model_query(context, models.Instance)
     for column in columns_to_join_new:
-        query = query.options(joinedload(column))
+        query = query.options(orm.joinedload(column))
     if not context.is_admin:
         # If we're not admin context, add appropriate filter..
         if context.project_id:
@@ -1673,9 +1661,9 @@ def instance_get_all_by_filters_sort(context, filters, limit=None, marker=None,
     query_prefix = context.session.query(models.Instance)
     for column in columns_to_join_new:
         if 'extra.' in column:
-            query_prefix = query_prefix.options(undefer(column))
+            query_prefix = query_prefix.options(orm.undefer(column))
         else:
-            query_prefix = query_prefix.options(joinedload(column))
+            query_prefix = query_prefix.options(orm.joinedload(column))
 
     # Note: order_by is done in the sqlalchemy.utils.py paginate_query(),
     # no need to do it here as well
@@ -1695,7 +1683,7 @@ def instance_get_all_by_filters_sort(context, filters, limit=None, marker=None,
         deleted = filters.pop('deleted')
         if deleted:
             if filters.pop('soft_deleted', True):
-                delete = or_(
+                delete = sql.or_(
                     models.Instance.deleted == models.Instance.id,
                     models.Instance.vm_state == vm_states.SOFT_DELETED
                     )
@@ -1710,10 +1698,10 @@ def instance_get_all_by_filters_sort(context, filters, limit=None, marker=None,
             if not filters.pop('soft_deleted', False):
                 # It would be better to have vm_state not be nullable
                 # but until then we test it explicitly as a workaround.
-                not_soft_deleted = or_(
+                not_soft_deleted = sql.or_(
                     models.Instance.vm_state != vm_states.SOFT_DELETED,
-                    models.Instance.vm_state == null()
-                    )
+                    models.Instance.vm_state == sql.null()
+                )
                 query_prefix = query_prefix.filter(not_soft_deleted)
 
     if 'cleaned' in filters:
@@ -1730,14 +1718,14 @@ def instance_get_all_by_filters_sort(context, filters, limit=None, marker=None,
         query_prefix = query_prefix.filter(models.Tag.tag == first_tag)
 
         for tag in tags:
-            tag_alias = aliased(models.Tag)
+            tag_alias = orm.aliased(models.Tag)
             query_prefix = query_prefix.join(tag_alias,
                                              models.Instance.tags)
             query_prefix = query_prefix.filter(tag_alias.tag == tag)
 
     if 'tags-any' in filters:
         tags = filters.pop('tags-any')
-        tag_alias = aliased(models.Tag)
+        tag_alias = orm.aliased(models.Tag)
         query_prefix = query_prefix.join(tag_alias, models.Instance.tags)
         query_prefix = query_prefix.filter(tag_alias.tag.in_(tags))
 
@@ -1749,7 +1737,7 @@ def instance_get_all_by_filters_sort(context, filters, limit=None, marker=None,
         subq = subq.filter(models.Tag.tag == first_tag)
 
         for tag in tags:
-            tag_alias = aliased(models.Tag)
+            tag_alias = orm.aliased(models.Tag)
             subq = subq.join(tag_alias, models.Instance.tags)
             subq = subq.filter(tag_alias.tag == tag)
 
@@ -1768,14 +1756,15 @@ def instance_get_all_by_filters_sort(context, filters, limit=None, marker=None,
             filters['user_id'] = context.user_id
 
     if filters.pop('hidden', False):
-        query_prefix = query_prefix.filter(models.Instance.hidden == true())
+        query_prefix = query_prefix.filter(
+            models.Instance.hidden == sql.true())
     else:
         # If the query should not include hidden instances, then
         # filter instances with hidden=False or hidden=NULL because
         # older records may have no value set.
-        query_prefix = query_prefix.filter(or_(
-            models.Instance.hidden == false(),
-            models.Instance.hidden == null()))
+        query_prefix = query_prefix.filter(sql.or_(
+            models.Instance.hidden == sql.false(),
+            models.Instance.hidden == sql.null()))
 
     # Filters for exact matches that we can do along with the SQL query...
     # For other filters that don't match this, we will do regexp matching
@@ -1856,9 +1845,9 @@ def _model_get_uuid_by_sort_filters(context, model, sort_keys, sort_dirs,
     for skey, sdir, val in zip(sort_keys, sort_dirs, values):
         # Apply ordering to our query for the key, direction we're processing
         if sdir == 'desc':
-            query = query.order_by(desc(getattr(model, skey)))
+            query = query.order_by(expression.desc(getattr(model, skey)))
         else:
-            query = query.order_by(asc(getattr(model, skey)))
+            query = query.order_by(expression.asc(getattr(model, skey)))
 
         # Build a list of equivalence requirements on keys we've already
         # processed through the loop. In other words, if we're adding
@@ -1869,8 +1858,8 @@ def _model_get_uuid_by_sort_filters(context, model, sort_keys, sort_dirs,
                 (getattr(model, sort_keys[equal_attr]) == values[equal_attr]))
 
         model_attr = getattr(model, skey)
-        if isinstance(model_attr.type, Boolean):
-            model_attr = cast(model_attr, Integer)
+        if isinstance(model_attr.type, sa.Boolean):
+            model_attr = expression.cast(model_attr, sa.Integer)
             val = int(val)
 
         if skey == sort_keys[-1]:
@@ -1890,11 +1879,11 @@ def _model_get_uuid_by_sort_filters(context, model, sort_keys, sort_dirs,
 
         # AND together all the above
         crit_attrs.append(crit)
-        criteria.append(and_(*crit_attrs))
+        criteria.append(sql.and_(*crit_attrs))
         key_index += 1
 
     # OR together all the ANDs
-    query = query.filter(or_(*criteria))
+    query = query.filter(sql.or_(*criteria))
 
     # We can't raise InstanceNotFound because we don't have a uuid to
     # be looking for, so just return nothing if no match.
@@ -2130,12 +2119,13 @@ def instance_get_active_by_window_joined(context, begin, end=None,
 
     for column in columns_to_join_new:
         if 'extra.' in column:
-            query = query.options(undefer(column))
+            query = query.options(orm.undefer(column))
         else:
-            query = query.options(joinedload(column))
+            query = query.options(orm.joinedload(column))
 
-    query = query.filter(or_(models.Instance.terminated_at == null(),
-                             models.Instance.terminated_at > begin))
+    query = query.filter(sql.or_(
+        models.Instance.terminated_at == sql.null(),
+        models.Instance.terminated_at > begin))
     if end:
         query = query.filter(models.Instance.launched_at < end)
     if project_id:
@@ -2165,9 +2155,9 @@ def _instance_get_all_query(context, project_only=False, joins=None):
                         project_only=project_only)
     for column in joins:
         if 'extra.' in column:
-            query = query.options(undefer(column))
+            query = query.options(orm.undefer(column))
         else:
-            query = query.options(joinedload(column))
+            query = query.options(orm.joinedload(column))
     return query
 
 
@@ -2581,7 +2571,7 @@ def instance_extra_get_by_instance_uuid(
         columns = ['numa_topology', 'pci_requests', 'flavor', 'vcpu_model',
                    'trusted_certs', 'resources', 'migration_context']
     for column in columns:
-        query = query.options(undefer(column))
+        query = query.options(orm.undefer(column))
     instance_extra = query.first()
     return instance_extra
 
@@ -2875,7 +2865,7 @@ def _block_device_mapping_get_query(context, columns_to_join=None):
     query = model_query(context, models.BlockDeviceMapping)
 
     for column in columns_to_join:
-        query = query.options(joinedload(column))
+        query = query.options(orm.joinedload(column))
 
     return query
 
@@ -3408,10 +3398,13 @@ def migration_get_in_progress_by_host_and_node(context, host, node):
     # and the instance is in VERIFY_RESIZE state, so the end state
     # for a resize is actually 'confirmed' or 'reverted'.
     return model_query(context, models.Migration).\
-            filter(or_(and_(models.Migration.source_compute == host,
-                            models.Migration.source_node == node),
-                       and_(models.Migration.dest_compute == host,
-                            models.Migration.dest_node == node))).\
+            filter(sql.or_(
+                sql.and_(
+                    models.Migration.source_compute == host,
+                    models.Migration.source_node == node),
+                sql.and_(
+                    models.Migration.dest_compute == host,
+                    models.Migration.dest_node == node))).\
             filter(~models.Migration.status.in_(['confirmed', 'reverted',
                                                  'error', 'failed',
                                                  'completed', 'cancelled',
@@ -3465,15 +3458,17 @@ def migration_get_all_by_filters(context, filters,
         query = query.filter(models.Migration.status.in_(status))
     if "host" in filters:
         host = filters["host"]
-        query = query.filter(or_(models.Migration.source_compute == host,
-                                 models.Migration.dest_compute == host))
+        query = query.filter(sql.or_(
+            models.Migration.source_compute == host,
+            models.Migration.dest_compute == host))
     elif "source_compute" in filters:
         host = filters['source_compute']
         query = query.filter(models.Migration.source_compute == host)
     if "node" in filters:
         node = filters['node']
-        query = query.filter(or_(models.Migration.source_node == node,
-                                 models.Migration.dest_node == node))
+        query = query.filter(sql.or_(
+            models.Migration.source_node == node,
+            models.Migration.dest_node == node))
     if "migration_type" in filters:
         migtype = filters["migration_type"]
         query = query.filter(models.Migration.migration_type == migtype)
@@ -3551,10 +3546,13 @@ def migration_get_in_progress_and_error_by_host_and_node(context, host, node):
     host and node.
     """
     return model_query(context, models.Migration).\
-            filter(or_(and_(models.Migration.source_compute == host,
-                            models.Migration.source_node == node),
-                       and_(models.Migration.dest_compute == host,
-                            models.Migration.dest_node == node))).\
+            filter(sql.or_(
+                sql.and_(
+                    models.Migration.source_compute == host,
+                    models.Migration.source_node == node),
+                sql.and_(
+                    models.Migration.dest_compute == host,
+                    models.Migration.dest_node == node))).\
             filter(~models.Migration.status.in_(['confirmed', 'reverted',
                                                  'failed', 'completed',
                                                  'cancelled', 'done'])).\
@@ -3738,11 +3736,11 @@ def bw_usage_update(
     # same record is updated every time. It can be removed after adding
     # unique constraint to this model.
     bw_usage = model_query(context, models.BandwidthUsage,
-            read_deleted='yes').\
-                    filter_by(start_period=ts_values['start_period']).\
-                    filter_by(uuid=uuid).\
-                    filter_by(mac=mac).\
-                    order_by(asc(models.BandwidthUsage.id)).first()
+        read_deleted='yes').\
+            filter_by(start_period=ts_values['start_period']).\
+            filter_by(uuid=uuid).\
+            filter_by(mac=mac).\
+            order_by(expression.asc(models.BandwidthUsage.id)).first()
 
     if bw_usage:
         bw_usage.update(values)
@@ -3770,11 +3768,12 @@ def bw_usage_update(
 def vol_get_usage_by_time(context, begin):
     """Return volumes usage that have been updated after a specified time."""
     return model_query(context, models.VolumeUsage, read_deleted="yes").\
-                   filter(or_(models.VolumeUsage.tot_last_refreshed == null(),
-                              models.VolumeUsage.tot_last_refreshed > begin,
-                              models.VolumeUsage.curr_last_refreshed == null(),
-                              models.VolumeUsage.curr_last_refreshed > begin,
-                              )).all()
+        filter(sql.or_(
+            models.VolumeUsage.tot_last_refreshed == sql.null(),
+            models.VolumeUsage.tot_last_refreshed > begin,
+            models.VolumeUsage.curr_last_refreshed == sql.null(),
+            models.VolumeUsage.curr_last_refreshed > begin,
+        )).all()
 
 
 @require_context
@@ -3992,8 +3991,9 @@ def instance_fault_get_by_instance_uuids(
         query = query.join(latest_faults,
                            faults_tbl.c.id == latest_faults.c.max_id)
     else:
-        query = query.filter(models.InstanceFault.instance_uuid.in_(
-                                        instance_uuids)).order_by(desc("id"))
+        query = query.filter(
+            models.InstanceFault.instance_uuid.in_(instance_uuids)
+        ).order_by(expression.desc("id"))
 
     output = {}
     for instance_uuid in instance_uuids:
@@ -4071,18 +4071,18 @@ def action_get_by_request_id(context, instance_uuid, request_id):
 
 def _action_get_by_request_id(context, instance_uuid, request_id):
     result = model_query(context, models.InstanceAction).\
-                         filter_by(instance_uuid=instance_uuid).\
-                         filter_by(request_id=request_id).\
-                         order_by(desc("created_at"), desc("id")).\
-                         first()
+        filter_by(instance_uuid=instance_uuid).\
+        filter_by(request_id=request_id).\
+        order_by(expression.desc("created_at"), expression.desc("id")).\
+        first()
     return result
 
 
 def _action_get_last_created_by_instance_uuid(context, instance_uuid):
-    result = (model_query(context, models.InstanceAction).
-                     filter_by(instance_uuid=instance_uuid).
-                     order_by(desc("created_at"), desc("id")).
-                     first())
+    result = model_query(context, models.InstanceAction).\
+        filter_by(instance_uuid=instance_uuid).\
+        order_by(expression.desc("created_at"), expression.desc("id")).\
+        first()
     return result
 
 
@@ -4180,9 +4180,9 @@ def action_event_finish(context, values):
 def action_events_get(context, action_id):
     """Get the events by action id."""
     events = model_query(context, models.InstanceActionEvent).\
-                         filter_by(action_id=action_id).\
-                         order_by(desc("created_at"), desc("id")).\
-                         all()
+        filter_by(action_id=action_id).\
+        order_by(expression.desc("created_at"), expression.desc("id")).\
+        all()
 
     return events
 
@@ -4376,9 +4376,9 @@ def _get_fk_stmts(metadata, conn, table, column, records):
         # Create the shadow table for the referencing table.
         fk_shadow_tablename = _SHADOW_TABLE_PREFIX + fk_table.name
         try:
-            fk_shadow_table = Table(fk_shadow_tablename, metadata,
-                                    autoload=True)
-        except NoSuchTableError:
+            fk_shadow_table = schema.Table(
+                fk_shadow_tablename, metadata, autoload=True)
+        except sqla_exc.NoSuchTableError:
             # No corresponding shadow table; skip it.
             continue
 
@@ -4472,8 +4472,8 @@ def _archive_deleted_rows_for_table(metadata, tablename, max_rows, before,
     rows_archived = 0
     deleted_instance_uuids = []
     try:
-        shadow_table = Table(shadow_tablename, metadata, autoload=True)
-    except NoSuchTableError:
+        shadow_table = schema.Table(shadow_tablename, metadata, autoload=True)
+    except sqla_exc.NoSuchTableError:
         # No corresponding shadow table; skip it.
         return rows_archived, deleted_instance_uuids, {}
 
@@ -4589,7 +4589,7 @@ def archive_deleted_rows(context=None, max_rows=None, before=None,
     table_to_rows_archived = collections.defaultdict(int)
     deleted_instance_uuids = []
     total_rows_archived = 0
-    meta = MetaData(get_engine(use_slave=True, context=context))
+    meta = sa.MetaData(get_engine(use_slave=True, context=context))
     meta.reflect()
     # Get the sorted list of tables in order of foreign key dependency.
     # Process the parent tables and find their dependent records in order to
@@ -4634,7 +4634,7 @@ def _purgeable_tables(metadata):
 def purge_shadow_tables(context, before_date, status_fn=None):
     engine = get_engine(context=context)
     conn = engine.connect()
-    metadata = MetaData()
+    metadata = sa.MetaData()
     metadata.bind = engine
     metadata.reflect()
     total_deleted = 0
diff --git a/nova/db/sqlalchemy/api_models.py b/nova/db/sqlalchemy/api_models.py
index ae85eddb72e0..74d6455d66de 100644
--- a/nova/db/sqlalchemy/api_models.py
+++ b/nova/db/sqlalchemy/api_models.py
@@ -13,28 +13,18 @@
 
 from oslo_db.sqlalchemy import models
 from oslo_log import log as logging
-from sqlalchemy import Boolean
-from sqlalchemy import Column
-from sqlalchemy import DateTime
-from sqlalchemy.dialects.mysql import MEDIUMTEXT
-from sqlalchemy import Enum
+import sqlalchemy as sa
+import sqlalchemy.dialects.mysql
 from sqlalchemy.ext.declarative import declarative_base
-from sqlalchemy import Float
-from sqlalchemy import ForeignKey
-from sqlalchemy import Index
-from sqlalchemy import Integer
 from sqlalchemy import orm
-from sqlalchemy.orm import backref
 from sqlalchemy import schema
-from sqlalchemy import String
-from sqlalchemy import Text
-from sqlalchemy import Unicode
 
 LOG = logging.getLogger(__name__)
 
 
 def MediumText():
-    return Text().with_variant(MEDIUMTEXT(), 'mysql')
+    return sa.Text().with_variant(
+        sqlalchemy.dialects.mysql.MEDIUMTEXT(), 'mysql')
 
 
 class _NovaAPIBase(models.ModelBase, models.TimestampMixin):
@@ -52,9 +42,10 @@ class AggregateHost(API_BASE):
          name="uniq_aggregate_hosts0host0aggregate_id"
         ),
     )
-    id = Column(Integer, primary_key=True, autoincrement=True)
-    host = Column(String(255))
-    aggregate_id = Column(Integer, ForeignKey('aggregates.id'), nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, autoincrement=True)
+    host = sa.Column(sa.String(255))
+    aggregate_id = sa.Column(
+        sa.Integer, sa.ForeignKey('aggregates.id'), nullable=False)
 
 
 class AggregateMetadata(API_BASE):
@@ -64,30 +55,33 @@ class AggregateMetadata(API_BASE):
         schema.UniqueConstraint("aggregate_id", "key",
             name="uniq_aggregate_metadata0aggregate_id0key"
             ),
-        Index('aggregate_metadata_key_idx', 'key'),
+        sa.Index('aggregate_metadata_key_idx', 'key'),
     )
-    id = Column(Integer, primary_key=True)
-    key = Column(String(255), nullable=False)
-    value = Column(String(255), nullable=False)
-    aggregate_id = Column(Integer, ForeignKey('aggregates.id'), nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True)
+    key = sa.Column(sa.String(255), nullable=False)
+    value = sa.Column(sa.String(255), nullable=False)
+    aggregate_id = sa.Column(
+        sa.Integer, sa.ForeignKey('aggregates.id'), nullable=False)
 
 
 class Aggregate(API_BASE):
     """Represents a cluster of hosts that exists in this zone."""
     __tablename__ = 'aggregates'
-    __table_args__ = (Index('aggregate_uuid_idx', 'uuid'),
-                      schema.UniqueConstraint(
-                      "name", name="uniq_aggregate0name")
-        )
-    id = Column(Integer, primary_key=True, autoincrement=True)
-    uuid = Column(String(36))
-    name = Column(String(255))
-    _hosts = orm.relationship(AggregateHost,
-                    primaryjoin='Aggregate.id == AggregateHost.aggregate_id',
-                    cascade='delete')
-    _metadata = orm.relationship(AggregateMetadata,
-                primaryjoin='Aggregate.id == AggregateMetadata.aggregate_id',
-                cascade='delete')
+    __table_args__ = (
+        sa.Index('aggregate_uuid_idx', 'uuid'),
+        schema.UniqueConstraint("name", name="uniq_aggregate0name")
+    )
+    id = sa.Column(sa.Integer, primary_key=True, autoincrement=True)
+    uuid = sa.Column(sa.String(36))
+    name = sa.Column(sa.String(255))
+    _hosts = orm.relationship(
+        AggregateHost,
+        primaryjoin='Aggregate.id == AggregateHost.aggregate_id',
+        cascade='delete')
+    _metadata = orm.relationship(
+        AggregateMetadata,
+        primaryjoin='Aggregate.id == AggregateMetadata.aggregate_id',
+        cascade='delete')
 
     @property
     def _extra_keys(self):
@@ -111,59 +105,67 @@ class Aggregate(API_BASE):
 class CellMapping(API_BASE):
     """Contains information on communicating with a cell"""
     __tablename__ = 'cell_mappings'
-    __table_args__ = (Index('uuid_idx', 'uuid'),
-                      schema.UniqueConstraint('uuid',
-                          name='uniq_cell_mappings0uuid'))
+    __table_args__ = (
+        sa.Index('uuid_idx', 'uuid'),
+        schema.UniqueConstraint('uuid', name='uniq_cell_mappings0uuid'),
+    )
 
-    id = Column(Integer, primary_key=True)
-    uuid = Column(String(36), nullable=False)
-    name = Column(String(255))
-    transport_url = Column(Text())
-    database_connection = Column(Text())
-    disabled = Column(Boolean, default=False)
-    host_mapping = orm.relationship('HostMapping',
-                            backref=backref('cell_mapping', uselist=False),
-                            foreign_keys=id,
-                            primaryjoin=(
-                                  'CellMapping.id == HostMapping.cell_id'))
+    id = sa.Column(sa.Integer, primary_key=True)
+    uuid = sa.Column(sa.String(36), nullable=False)
+    name = sa.Column(sa.String(255))
+    transport_url = sa.Column(sa.Text())
+    database_connection = sa.Column(sa.Text())
+    disabled = sa.Column(sa.Boolean, default=False)
+    host_mapping = orm.relationship(
+        'HostMapping',
+        backref=orm.backref('cell_mapping', uselist=False),
+        foreign_keys=id,
+        primaryjoin='CellMapping.id == HostMapping.cell_id')
 
 
 class InstanceMapping(API_BASE):
     """Contains the mapping of an instance to which cell it is in"""
     __tablename__ = 'instance_mappings'
-    __table_args__ = (Index('project_id_idx', 'project_id'),
-                      Index('instance_uuid_idx', 'instance_uuid'),
-                      schema.UniqueConstraint('instance_uuid',
-                          name='uniq_instance_mappings0instance_uuid'),
-                      Index('instance_mappings_user_id_project_id_idx',
-                            'user_id', 'project_id'))
+    __table_args__ = (
+        sa.Index('project_id_idx', 'project_id'),
+        sa.Index('instance_uuid_idx', 'instance_uuid'),
+        schema.UniqueConstraint(
+            'instance_uuid', name='uniq_instance_mappings0instance_uuid'),
+        sa.Index(
+            'instance_mappings_user_id_project_id_idx',
+            'user_id',
+            'project_id',
+        ),
+    )
 
-    id = Column(Integer, primary_key=True)
-    instance_uuid = Column(String(36), nullable=False)
-    cell_id = Column(Integer, ForeignKey('cell_mappings.id'),
-            nullable=True)
-    project_id = Column(String(255), nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True)
+    instance_uuid = sa.Column(sa.String(36), nullable=False)
+    cell_id = sa.Column(
+        sa.Integer, sa.ForeignKey('cell_mappings.id'), nullable=True)
+    project_id = sa.Column(sa.String(255), nullable=False)
     # FIXME(melwitt): This should eventually be non-nullable, but we need a
     # transition period first.
-    user_id = Column(String(255), nullable=True)
-    queued_for_delete = Column(Boolean)
-    cell_mapping = orm.relationship('CellMapping',
-            backref=backref('instance_mapping', uselist=False),
-            foreign_keys=cell_id,
-            primaryjoin=('InstanceMapping.cell_id == CellMapping.id'))
+    user_id = sa.Column(sa.String(255), nullable=True)
+    queued_for_delete = sa.Column(sa.Boolean)
+    cell_mapping = orm.relationship(
+        'CellMapping',
+        backref=orm.backref('instance_mapping', uselist=False),
+        foreign_keys=cell_id,
+        primaryjoin='InstanceMapping.cell_id == CellMapping.id')
 
 
 class HostMapping(API_BASE):
     """Contains mapping of a compute host to which cell it is in"""
     __tablename__ = "host_mappings"
-    __table_args__ = (Index('host_idx', 'host'),
-                      schema.UniqueConstraint('host',
-                        name='uniq_host_mappings0host'))
+    __table_args__ = (
+        sa.Index('host_idx', 'host'),
+        schema.UniqueConstraint('host', name='uniq_host_mappings0host'),
+    )
 
-    id = Column(Integer, primary_key=True)
-    cell_id = Column(Integer, ForeignKey('cell_mappings.id'),
-            nullable=False)
-    host = Column(String(255), nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True)
+    cell_id = sa.Column(
+        sa.Integer, sa.ForeignKey('cell_mappings.id'), nullable=False)
+    host = sa.Column(sa.String(255), nullable=False)
 
 
 class RequestSpec(API_BASE):
@@ -171,14 +173,14 @@ class RequestSpec(API_BASE):
 
     __tablename__ = 'request_specs'
     __table_args__ = (
-        Index('request_spec_instance_uuid_idx', 'instance_uuid'),
-        schema.UniqueConstraint('instance_uuid',
-            name='uniq_request_specs0instance_uuid'),
-        )
+        sa.Index('request_spec_instance_uuid_idx', 'instance_uuid'),
+        schema.UniqueConstraint(
+            'instance_uuid', name='uniq_request_specs0instance_uuid'),
+    )
 
-    id = Column(Integer, primary_key=True)
-    instance_uuid = Column(String(36), nullable=False)
-    spec = Column(MediumText(), nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True)
+    instance_uuid = sa.Column(sa.String(36), nullable=False)
+    spec = sa.Column(MediumText(), nullable=False)
 
 
 class Flavors(API_BASE):
@@ -188,39 +190,40 @@ class Flavors(API_BASE):
         schema.UniqueConstraint("flavorid", name="uniq_flavors0flavorid"),
         schema.UniqueConstraint("name", name="uniq_flavors0name"))
 
-    id = Column(Integer, primary_key=True)
-    name = Column(String(255), nullable=False)
-    memory_mb = Column(Integer, nullable=False)
-    vcpus = Column(Integer, nullable=False)
-    root_gb = Column(Integer)
-    ephemeral_gb = Column(Integer)
-    flavorid = Column(String(255), nullable=False)
-    swap = Column(Integer, nullable=False, default=0)
-    rxtx_factor = Column(Float, default=1)
-    vcpu_weight = Column(Integer)
-    disabled = Column(Boolean, default=False)
-    is_public = Column(Boolean, default=True)
-    description = Column(Text)
+    id = sa.Column(sa.Integer, primary_key=True)
+    name = sa.Column(sa.String(255), nullable=False)
+    memory_mb = sa.Column(sa.Integer, nullable=False)
+    vcpus = sa.Column(sa.Integer, nullable=False)
+    root_gb = sa.Column(sa.Integer)
+    ephemeral_gb = sa.Column(sa.Integer)
+    flavorid = sa.Column(sa.String(255), nullable=False)
+    swap = sa.Column(sa.Integer, nullable=False, default=0)
+    rxtx_factor = sa.Column(sa.Float, default=1)
+    vcpu_weight = sa.Column(sa.Integer)
+    disabled = sa.Column(sa.Boolean, default=False)
+    is_public = sa.Column(sa.Boolean, default=True)
+    description = sa.Column(sa.Text)
 
 
 class FlavorExtraSpecs(API_BASE):
     """Represents additional specs as key/value pairs for a flavor"""
     __tablename__ = 'flavor_extra_specs'
     __table_args__ = (
-        Index('flavor_extra_specs_flavor_id_key_idx', 'flavor_id', 'key'),
+        sa.Index('flavor_extra_specs_flavor_id_key_idx', 'flavor_id', 'key'),
         schema.UniqueConstraint('flavor_id', 'key',
             name='uniq_flavor_extra_specs0flavor_id0key'),
         {'mysql_collate': 'utf8_bin'},
     )
 
-    id = Column(Integer, primary_key=True)
-    key = Column(String(255), nullable=False)
-    value = Column(String(255))
-    flavor_id = Column(Integer, ForeignKey('flavors.id'), nullable=False)
-    flavor = orm.relationship(Flavors, backref='extra_specs',
-                              foreign_keys=flavor_id,
-                              primaryjoin=(
-                                  'FlavorExtraSpecs.flavor_id == Flavors.id'))
+    id = sa.Column(sa.Integer, primary_key=True)
+    key = sa.Column(sa.String(255), nullable=False)
+    value = sa.Column(sa.String(255))
+    flavor_id = sa.Column(
+        sa.Integer, sa.ForeignKey('flavors.id'), nullable=False)
+    flavor = orm.relationship(
+        Flavors, backref='extra_specs',
+        foreign_keys=flavor_id,
+        primaryjoin='FlavorExtraSpecs.flavor_id == Flavors.id')
 
 
 class FlavorProjects(API_BASE):
@@ -229,13 +232,14 @@ class FlavorProjects(API_BASE):
     __table_args__ = (schema.UniqueConstraint('flavor_id', 'project_id',
         name='uniq_flavor_projects0flavor_id0project_id'),)
 
-    id = Column(Integer, primary_key=True)
-    flavor_id = Column(Integer, ForeignKey('flavors.id'), nullable=False)
-    project_id = Column(String(255), nullable=False)
-    flavor = orm.relationship(Flavors, backref='projects',
-                              foreign_keys=flavor_id,
-                              primaryjoin=(
-                                  'FlavorProjects.flavor_id == Flavors.id'))
+    id = sa.Column(sa.Integer, primary_key=True)
+    flavor_id = sa.Column(
+        sa.Integer, sa.ForeignKey('flavors.id'), nullable=False)
+    project_id = sa.Column(sa.String(255), nullable=False)
+    flavor = orm.relationship(
+        Flavors, backref='projects',
+        foreign_keys=flavor_id,
+        primaryjoin='FlavorProjects.flavor_id == Flavors.id')
 
 
 class BuildRequest(API_BASE):
@@ -243,19 +247,19 @@ class BuildRequest(API_BASE):
 
     __tablename__ = 'build_requests'
     __table_args__ = (
-        Index('build_requests_instance_uuid_idx', 'instance_uuid'),
-        Index('build_requests_project_id_idx', 'project_id'),
-        schema.UniqueConstraint('instance_uuid',
-            name='uniq_build_requests0instance_uuid'),
-        )
+        sa.Index('build_requests_instance_uuid_idx', 'instance_uuid'),
+        sa.Index('build_requests_project_id_idx', 'project_id'),
+        schema.UniqueConstraint(
+            'instance_uuid', name='uniq_build_requests0instance_uuid'),
+    )
 
-    id = Column(Integer, primary_key=True)
+    id = sa.Column(sa.Integer, primary_key=True)
     # TODO(mriedem): instance_uuid should be nullable=False
-    instance_uuid = Column(String(36))
-    project_id = Column(String(255), nullable=False)
-    instance = Column(MediumText())
-    block_device_mappings = Column(MediumText())
-    tags = Column(Text())
+    instance_uuid = sa.Column(sa.String(36))
+    project_id = sa.Column(sa.String(255), nullable=False)
+    instance = sa.Column(MediumText())
+    block_device_mappings = sa.Column(MediumText())
+    tags = sa.Column(sa.Text())
     # TODO(alaski): Drop these from the db in Ocata
     # columns_to_drop = ['request_spec_id', 'user_id', 'display_name',
     #         'instance_metadata', 'progress', 'vm_state', 'task_state',
@@ -269,19 +273,18 @@ class KeyPair(API_BASE):
     """Represents a public key pair for ssh / WinRM."""
     __tablename__ = 'key_pairs'
     __table_args__ = (
-        schema.UniqueConstraint("user_id", "name",
-                                name="uniq_key_pairs0user_id0name"),
+        schema.UniqueConstraint(
+            "user_id", "name", name="uniq_key_pairs0user_id0name"),
     )
-    id = Column(Integer, primary_key=True, nullable=False)
 
-    name = Column(String(255), nullable=False)
-
-    user_id = Column(String(255), nullable=False)
-
-    fingerprint = Column(String(255))
-    public_key = Column(Text())
-    type = Column(Enum('ssh', 'x509', name='keypair_types'),
-                  nullable=False, server_default='ssh')
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    name = sa.Column(sa.String(255), nullable=False)
+    user_id = sa.Column(sa.String(255), nullable=False)
+    fingerprint = sa.Column(sa.String(255))
+    public_key = sa.Column(sa.Text())
+    type = sa.Column(
+        sa.Enum('ssh', 'x509', name='keypair_types'),
+        nullable=False, server_default='ssh')
 
 
 # TODO(stephenfin): Remove this as it's now unused post-placement split
@@ -292,8 +295,8 @@ class ResourceClass(API_BASE):
         schema.UniqueConstraint("name", name="uniq_resource_classes0name"),
     )
 
-    id = Column(Integer, primary_key=True, nullable=False)
-    name = Column(String(255), nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    name = sa.Column(sa.String(255), nullable=False)
 
 
 # TODO(stephenfin): Remove this as it's now unused post-placement split
@@ -302,29 +305,28 @@ class ResourceProvider(API_BASE):
 
     __tablename__ = "resource_providers"
     __table_args__ = (
-        Index('resource_providers_uuid_idx', 'uuid'),
-        schema.UniqueConstraint('uuid',
-            name='uniq_resource_providers0uuid'),
-        Index('resource_providers_name_idx', 'name'),
-        Index('resource_providers_root_provider_id_idx',
-              'root_provider_id'),
-        Index('resource_providers_parent_provider_id_idx',
-              'parent_provider_id'),
-        schema.UniqueConstraint('name',
-            name='uniq_resource_providers0name')
+        sa.Index('resource_providers_uuid_idx', 'uuid'),
+        schema.UniqueConstraint('uuid', name='uniq_resource_providers0uuid'),
+        sa.Index('resource_providers_name_idx', 'name'),
+        sa.Index(
+            'resource_providers_root_provider_id_idx', 'root_provider_id'),
+        sa.Index(
+            'resource_providers_parent_provider_id_idx', 'parent_provider_id'),
+        schema.UniqueConstraint(
+            'name', name='uniq_resource_providers0name')
     )
 
-    id = Column(Integer, primary_key=True, nullable=False)
-    uuid = Column(String(36), nullable=False)
-    name = Column(Unicode(200), nullable=True)
-    generation = Column(Integer, default=0)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    uuid = sa.Column(sa.String(36), nullable=False)
+    name = sa.Column(sa.Unicode(200), nullable=True)
+    generation = sa.Column(sa.Integer, default=0)
     # Represents the root of the "tree" that the provider belongs to
-    root_provider_id = Column(Integer, ForeignKey('resource_providers.id'),
-        nullable=True)
+    root_provider_id = sa.Column(
+        sa.Integer, sa.ForeignKey('resource_providers.id'), nullable=True)
     # The immediate parent provider of this provider, or NULL if there is no
     # parent. If parent_provider_id == NULL then root_provider_id == id
-    parent_provider_id = Column(Integer, ForeignKey('resource_providers.id'),
-        nullable=True)
+    parent_provider_id = sa.Column(
+        sa.Integer, sa.ForeignKey('resource_providers.id'), nullable=True)
 
 
 # TODO(stephenfin): Remove this as it's now unused post-placement split
@@ -333,29 +335,34 @@ class Inventory(API_BASE):
 
     __tablename__ = "inventories"
     __table_args__ = (
-        Index('inventories_resource_provider_id_idx',
-              'resource_provider_id'),
-        Index('inventories_resource_class_id_idx',
-              'resource_class_id'),
-        Index('inventories_resource_provider_resource_class_idx',
-              'resource_provider_id', 'resource_class_id'),
-        schema.UniqueConstraint('resource_provider_id', 'resource_class_id',
-            name='uniq_inventories0resource_provider_resource_class')
+        sa.Index(
+            'inventories_resource_provider_id_idx', 'resource_provider_id'),
+        sa.Index(
+            'inventories_resource_class_id_idx', 'resource_class_id'),
+        sa.Index(
+            'inventories_resource_provider_resource_class_idx',
+            'resource_provider_id',
+            'resource_class_id',
+        ),
+        schema.UniqueConstraint(
+            'resource_provider_id',
+            'resource_class_id',
+            name='uniq_inventories0resource_provider_resource_class'
+        ),
     )
 
-    id = Column(Integer, primary_key=True, nullable=False)
-    resource_provider_id = Column(Integer, nullable=False)
-    resource_class_id = Column(Integer, nullable=False)
-    total = Column(Integer, nullable=False)
-    reserved = Column(Integer, nullable=False)
-    min_unit = Column(Integer, nullable=False)
-    max_unit = Column(Integer, nullable=False)
-    step_size = Column(Integer, nullable=False)
-    allocation_ratio = Column(Float, nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    resource_provider_id = sa.Column(sa.Integer, nullable=False)
+    resource_class_id = sa.Column(sa.Integer, nullable=False)
+    total = sa.Column(sa.Integer, nullable=False)
+    reserved = sa.Column(sa.Integer, nullable=False)
+    min_unit = sa.Column(sa.Integer, nullable=False)
+    max_unit = sa.Column(sa.Integer, nullable=False)
+    step_size = sa.Column(sa.Integer, nullable=False)
+    allocation_ratio = sa.Column(sa.Float, nullable=False)
     resource_provider = orm.relationship(
         "ResourceProvider",
-        primaryjoin=('Inventory.resource_provider_id == '
-                     'ResourceProvider.id'),
+        primaryjoin='Inventory.resource_provider_id == ResourceProvider.id',
         foreign_keys=resource_provider_id)
 
 
@@ -365,23 +372,24 @@ class Allocation(API_BASE):
 
     __tablename__ = "allocations"
     __table_args__ = (
-        Index('allocations_resource_provider_class_used_idx',
-              'resource_provider_id', 'resource_class_id',
-              'used'),
-        Index('allocations_resource_class_id_idx',
-              'resource_class_id'),
-        Index('allocations_consumer_id_idx', 'consumer_id')
+        sa.Index(
+            'allocations_resource_provider_class_used_idx',
+            'resource_provider_id',
+            'resource_class_id',
+            'used',
+        ),
+        sa.Index('allocations_resource_class_id_idx', 'resource_class_id'),
+        sa.Index('allocations_consumer_id_idx', 'consumer_id')
     )
 
-    id = Column(Integer, primary_key=True, nullable=False)
-    resource_provider_id = Column(Integer, nullable=False)
-    consumer_id = Column(String(36), nullable=False)
-    resource_class_id = Column(Integer, nullable=False)
-    used = Column(Integer, nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    resource_provider_id = sa.Column(sa.Integer, nullable=False)
+    consumer_id = sa.Column(sa.String(36), nullable=False)
+    resource_class_id = sa.Column(sa.Integer, nullable=False)
+    used = sa.Column(sa.Integer, nullable=False)
     resource_provider = orm.relationship(
         "ResourceProvider",
-        primaryjoin=('Allocation.resource_provider_id == '
-                     'ResourceProvider.id'),
+        primaryjoin='Allocation.resource_provider_id == ResourceProvider.id',
         foreign_keys=resource_provider_id)
 
 
@@ -391,12 +399,13 @@ class ResourceProviderAggregate(API_BASE):
 
     __tablename__ = 'resource_provider_aggregates'
     __table_args__ = (
-        Index('resource_provider_aggregates_aggregate_id_idx',
-              'aggregate_id'),
+        sa.Index(
+            'resource_provider_aggregates_aggregate_id_idx', 'aggregate_id'),
     )
 
-    resource_provider_id = Column(Integer, primary_key=True, nullable=False)
-    aggregate_id = Column(Integer, primary_key=True, nullable=False)
+    resource_provider_id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False)
+    aggregate_id = sa.Column(sa.Integer, primary_key=True, nullable=False)
 
 
 # TODO(stephenfin): Remove this as it's now unused post-placement split
@@ -407,33 +416,34 @@ class PlacementAggregate(API_BASE):
         schema.UniqueConstraint("uuid", name="uniq_placement_aggregates0uuid"),
     )
 
-    id = Column(Integer, primary_key=True, autoincrement=True)
-    uuid = Column(String(36), index=True)
+    id = sa.Column(sa.Integer, primary_key=True, autoincrement=True)
+    uuid = sa.Column(sa.String(36), index=True)
 
 
 class InstanceGroupMember(API_BASE):
     """Represents the members for an instance group."""
     __tablename__ = 'instance_group_member'
     __table_args__ = (
-        Index('instance_group_member_instance_idx', 'instance_uuid'),
+        sa.Index('instance_group_member_instance_idx', 'instance_uuid'),
     )
-    id = Column(Integer, primary_key=True, nullable=False)
-    instance_uuid = Column(String(255))
-    group_id = Column(Integer, ForeignKey('instance_groups.id'),
-                      nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    instance_uuid = sa.Column(sa.String(255))
+    group_id = sa.Column(
+        sa.Integer, sa.ForeignKey('instance_groups.id'), nullable=False)
 
 
 class InstanceGroupPolicy(API_BASE):
     """Represents the policy type for an instance group."""
     __tablename__ = 'instance_group_policy'
     __table_args__ = (
-        Index('instance_group_policy_policy_idx', 'policy'),
+        sa.Index('instance_group_policy_policy_idx', 'policy'),
     )
-    id = Column(Integer, primary_key=True, nullable=False)
-    policy = Column(String(255))
-    group_id = Column(Integer, ForeignKey('instance_groups.id'),
-                      nullable=False)
-    rules = Column(Text)
+
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    policy = sa.Column(sa.String(255))
+    group_id = sa.Column(
+        sa.Integer, sa.ForeignKey('instance_groups.id'), nullable=False)
+    rules = sa.Column(sa.Text)
 
 
 class InstanceGroup(API_BASE):
@@ -448,15 +458,17 @@ class InstanceGroup(API_BASE):
         schema.UniqueConstraint('uuid', name='uniq_instance_groups0uuid'),
     )
 
-    id = Column(Integer, primary_key=True, autoincrement=True)
-    user_id = Column(String(255))
-    project_id = Column(String(255))
-    uuid = Column(String(36), nullable=False)
-    name = Column(String(255))
-    _policies = orm.relationship(InstanceGroupPolicy,
-            primaryjoin='InstanceGroup.id == InstanceGroupPolicy.group_id')
-    _members = orm.relationship(InstanceGroupMember,
-            primaryjoin='InstanceGroup.id == InstanceGroupMember.group_id')
+    id = sa.Column(sa.Integer, primary_key=True, autoincrement=True)
+    user_id = sa.Column(sa.String(255))
+    project_id = sa.Column(sa.String(255))
+    uuid = sa.Column(sa.String(36), nullable=False)
+    name = sa.Column(sa.String(255))
+    _policies = orm.relationship(
+        InstanceGroupPolicy,
+        primaryjoin='InstanceGroup.id == InstanceGroupPolicy.group_id')
+    _members = orm.relationship(
+        InstanceGroupMember,
+        primaryjoin='InstanceGroup.id == InstanceGroupMember.group_id')
 
     @property
     def policy(self):
@@ -482,41 +494,43 @@ class Quota(API_BASE):
     deployment is used. If the row is present but the hard limit is
     Null, then the resource is unlimited.
     """
-
     __tablename__ = 'quotas'
     __table_args__ = (
-        schema.UniqueConstraint("project_id", "resource",
-        name="uniq_quotas0project_id0resource"
+        schema.UniqueConstraint(
+            "project_id",
+            "resource",
+            name="uniq_quotas0project_id0resource"
         ),
     )
-    id = Column(Integer, primary_key=True)
 
-    project_id = Column(String(255))
-
-    resource = Column(String(255), nullable=False)
-    hard_limit = Column(Integer)
+    id = sa.Column(sa.Integer, primary_key=True)
+    project_id = sa.Column(sa.String(255))
+    resource = sa.Column(sa.String(255), nullable=False)
+    hard_limit = sa.Column(sa.Integer)
 
 
 class ProjectUserQuota(API_BASE):
     """Represents a single quota override for a user with in a project."""
 
     __tablename__ = 'project_user_quotas'
-    uniq_name = "uniq_project_user_quotas0user_id0project_id0resource"
     __table_args__ = (
-        schema.UniqueConstraint("user_id", "project_id", "resource",
-                                name=uniq_name),
-        Index('project_user_quotas_project_id_idx',
-              'project_id'),
-        Index('project_user_quotas_user_id_idx',
-              'user_id',)
+        schema.UniqueConstraint(
+            "user_id",
+            "project_id",
+            "resource",
+            name="uniq_project_user_quotas0user_id0project_id0resource",
+        ),
+        sa.Index(
+            'project_user_quotas_project_id_idx', 'project_id'),
+        sa.Index(
+            'project_user_quotas_user_id_idx', 'user_id',)
     )
-    id = Column(Integer, primary_key=True, nullable=False)
 
-    project_id = Column(String(255), nullable=False)
-    user_id = Column(String(255), nullable=False)
-
-    resource = Column(String(255), nullable=False)
-    hard_limit = Column(Integer)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    project_id = sa.Column(sa.String(255), nullable=False)
+    user_id = sa.Column(sa.String(255), nullable=False)
+    resource = sa.Column(sa.String(255), nullable=False)
+    hard_limit = sa.Column(sa.Integer)
 
 
 class QuotaClass(API_BASE):
@@ -529,14 +543,14 @@ class QuotaClass(API_BASE):
 
     __tablename__ = 'quota_classes'
     __table_args__ = (
-        Index('quota_classes_class_name_idx', 'class_name'),
+        sa.Index('quota_classes_class_name_idx', 'class_name'),
     )
-    id = Column(Integer, primary_key=True)
+    id = sa.Column(sa.Integer, primary_key=True)
 
-    class_name = Column(String(255))
+    class_name = sa.Column(sa.String(255))
 
-    resource = Column(String(255))
-    hard_limit = Column(Integer)
+    resource = sa.Column(sa.String(255))
+    hard_limit = sa.Column(sa.Integer)
 
 
 class QuotaUsage(API_BASE):
@@ -544,23 +558,22 @@ class QuotaUsage(API_BASE):
 
     __tablename__ = 'quota_usages'
     __table_args__ = (
-        Index('quota_usages_project_id_idx', 'project_id'),
-        Index('quota_usages_user_id_idx', 'user_id'),
+        sa.Index('quota_usages_project_id_idx', 'project_id'),
+        sa.Index('quota_usages_user_id_idx', 'user_id'),
     )
-    id = Column(Integer, primary_key=True)
 
-    project_id = Column(String(255))
-    user_id = Column(String(255))
-    resource = Column(String(255), nullable=False)
-
-    in_use = Column(Integer, nullable=False)
-    reserved = Column(Integer, nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True)
+    project_id = sa.Column(sa.String(255))
+    user_id = sa.Column(sa.String(255))
+    resource = sa.Column(sa.String(255), nullable=False)
+    in_use = sa.Column(sa.Integer, nullable=False)
+    reserved = sa.Column(sa.Integer, nullable=False)
 
     @property
     def total(self):
         return self.in_use + self.reserved
 
-    until_refresh = Column(Integer)
+    until_refresh = sa.Column(sa.Integer)
 
 
 class Reservation(API_BASE):
@@ -568,23 +581,21 @@ class Reservation(API_BASE):
 
     __tablename__ = 'reservations'
     __table_args__ = (
-        Index('reservations_project_id_idx', 'project_id'),
-        Index('reservations_uuid_idx', 'uuid'),
-        Index('reservations_expire_idx', 'expire'),
-        Index('reservations_user_id_idx', 'user_id'),
+        sa.Index('reservations_project_id_idx', 'project_id'),
+        sa.Index('reservations_uuid_idx', 'uuid'),
+        sa.Index('reservations_expire_idx', 'expire'),
+        sa.Index('reservations_user_id_idx', 'user_id'),
     )
-    id = Column(Integer, primary_key=True, nullable=False)
-    uuid = Column(String(36), nullable=False)
-
-    usage_id = Column(Integer, ForeignKey('quota_usages.id'), nullable=False)
-
-    project_id = Column(String(255))
-    user_id = Column(String(255))
-    resource = Column(String(255))
-
-    delta = Column(Integer, nullable=False)
-    expire = Column(DateTime)
 
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    uuid = sa.Column(sa.String(36), nullable=False)
+    usage_id = sa.Column(
+        sa.Integer, sa.ForeignKey('quota_usages.id'), nullable=False)
+    project_id = sa.Column(sa.String(255))
+    user_id = sa.Column(sa.String(255))
+    resource = sa.Column(sa.String(255))
+    delta = sa.Column(sa.Integer, nullable=False)
+    expire = sa.Column(sa.DateTime)
     usage = orm.relationship(
         "QuotaUsage",
         foreign_keys=usage_id,
@@ -599,8 +610,9 @@ class Trait(API_BASE):
         schema.UniqueConstraint('name', name='uniq_traits0name'),
     )
 
-    id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
-    name = Column(Unicode(255), nullable=False)
+    id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False, autoincrement=True)
+    name = sa.Column(sa.Unicode(255), nullable=False)
 
 
 # TODO(stephenfin): Remove this as it's now unused post-placement split
@@ -609,16 +621,18 @@ class ResourceProviderTrait(API_BASE):
 
     __tablename__ = "resource_provider_traits"
     __table_args__ = (
-        Index('resource_provider_traits_resource_provider_trait_idx',
+        sa.Index('resource_provider_traits_resource_provider_trait_idx',
               'resource_provider_id', 'trait_id'),
     )
 
-    trait_id = Column(Integer, ForeignKey('traits.id'), primary_key=True,
-                      nullable=False)
-    resource_provider_id = Column(Integer,
-                                  ForeignKey('resource_providers.id'),
-                                  primary_key=True,
-                                  nullable=False)
+    trait_id = sa.Column(
+        sa.Integer, sa.ForeignKey('traits.id'), primary_key=True,
+        nullable=False)
+    resource_provider_id = sa.Column(
+        sa.Integer,
+        sa.ForeignKey('resource_providers.id'),
+        primary_key=True,
+        nullable=False)
 
 
 # TODO(stephenfin): Remove this as it's unused
@@ -633,8 +647,9 @@ class Project(API_BASE):
         ),
     )
 
-    id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
-    external_id = Column(String(255), nullable=False)
+    id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False, autoincrement=True)
+    external_id = sa.Column(sa.String(255), nullable=False)
 
 
 # TODO(stephenfin): Remove this as it's unused
@@ -643,14 +658,12 @@ class User(API_BASE):
 
     __tablename__ = 'users'
     __table_args__ = (
-        schema.UniqueConstraint(
-            'external_id',
-            name='uniq_users0external_id',
-        ),
+        schema.UniqueConstraint('external_id', name='uniq_users0external_id'),
     )
 
-    id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
-    external_id = Column(String(255), nullable=False)
+    id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False, autoincrement=True)
+    external_id = sa.Column(sa.String(255), nullable=False)
 
 
 # TODO(stephenfin): Remove this as it's unused
@@ -659,16 +672,22 @@ class Consumer(API_BASE):
 
     __tablename__ = 'consumers'
     __table_args__ = (
-        Index('consumers_project_id_uuid_idx', 'project_id', 'uuid'),
-        Index('consumers_project_id_user_id_uuid_idx', 'project_id', 'user_id',
-              'uuid'),
+        sa.Index('consumers_project_id_uuid_idx', 'project_id', 'uuid'),
+        sa.Index(
+            'consumers_project_id_user_id_uuid_idx',
+            'project_id',
+            'user_id',
+            'uuid',
+        ),
         schema.UniqueConstraint('uuid', name='uniq_consumers0uuid'),
     )
 
-    id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
-    uuid = Column(String(36), nullable=False)
-    project_id = Column(Integer, nullable=False)
-    user_id = Column(Integer, nullable=False)
+    id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False, autoincrement=True)
+    uuid = sa.Column(sa.String(36), nullable=False)
+    project_id = sa.Column(sa.Integer, nullable=False)
+    user_id = sa.Column(sa.Integer, nullable=False)
     # FIXME(mriedem): Change this to server_default=text("0") to match the
     # 059_add_consumer_generation script once bug 1776527 is fixed.
-    generation = Column(Integer, nullable=False, server_default="0", default=0)
+    generation = sa.Column(
+        sa.Integer, nullable=False, server_default="0", default=0)
diff --git a/nova/db/sqlalchemy/models.py b/nova/db/sqlalchemy/models.py
index 120ce54ee720..08edcaedd016 100644
--- a/nova/db/sqlalchemy/models.py
+++ b/nova/db/sqlalchemy/models.py
@@ -22,21 +22,21 @@ SQLAlchemy models for nova data.
 from oslo_config import cfg
 from oslo_db.sqlalchemy import models
 from oslo_utils import timeutils
-from sqlalchemy import (Column, Index, Integer, BigInteger, Enum, String,
-                        schema, Unicode)
-from sqlalchemy.dialects.mysql import MEDIUMTEXT
-from sqlalchemy.ext.declarative import declarative_base
+import sqlalchemy as sa
+import sqlalchemy.dialects.mysql
+from sqlalchemy.ext import declarative
 from sqlalchemy import orm
-from sqlalchemy import ForeignKey, DateTime, Boolean, Text, Float
+from sqlalchemy import schema
 
 from nova.db.sqlalchemy import types
 
 CONF = cfg.CONF
-BASE = declarative_base()
+BASE = declarative.declarative_base()
 
 
 def MediumText():
-    return Text().with_variant(MEDIUMTEXT(), 'mysql')
+    return sa.Text().with_variant(
+        sqlalchemy.dialects.mysql.MEDIUMTEXT(), 'mysql')
 
 
 class NovaBase(models.TimestampMixin,
@@ -82,20 +82,20 @@ class Service(BASE, NovaBase, models.SoftDeleteMixin):
                                 name="uniq_services0host0topic0deleted"),
         schema.UniqueConstraint("host", "binary", "deleted",
                                 name="uniq_services0host0binary0deleted"),
-        Index('services_uuid_idx', 'uuid', unique=True),
+        sa.Index('services_uuid_idx', 'uuid', unique=True),
     )
 
-    id = Column(Integer, primary_key=True)
-    uuid = Column(String(36), nullable=True)
-    host = Column(String(255))
-    binary = Column(String(255))
-    topic = Column(String(255))
-    report_count = Column(Integer, nullable=False, default=0)
-    disabled = Column(Boolean, default=False)
-    disabled_reason = Column(String(255))
-    last_seen_up = Column(DateTime, nullable=True)
-    forced_down = Column(Boolean, default=False)
-    version = Column(Integer, default=0)
+    id = sa.Column(sa.Integer, primary_key=True)
+    uuid = sa.Column(sa.String(36), nullable=True)
+    host = sa.Column(sa.String(255))
+    binary = sa.Column(sa.String(255))
+    topic = sa.Column(sa.String(255))
+    report_count = sa.Column(sa.Integer, nullable=False, default=0)
+    disabled = sa.Column(sa.Boolean, default=False)
+    disabled_reason = sa.Column(sa.String(255))
+    last_seen_up = sa.Column(sa.DateTime, nullable=True)
+    forced_down = sa.Column(sa.Boolean, default=False)
+    version = sa.Column(sa.Integer, default=0)
 
     instance = orm.relationship(
         "Instance",
@@ -112,38 +112,38 @@ class ComputeNode(BASE, NovaBase, models.SoftDeleteMixin):
 
     __tablename__ = 'compute_nodes'
     __table_args__ = (
-        Index('compute_nodes_uuid_idx', 'uuid', unique=True),
+        sa.Index('compute_nodes_uuid_idx', 'uuid', unique=True),
         schema.UniqueConstraint(
             'host', 'hypervisor_hostname', 'deleted',
             name="uniq_compute_nodes0host0hypervisor_hostname0deleted"),
     )
-    id = Column(Integer, primary_key=True)
-    service_id = Column(Integer, nullable=True)
+    id = sa.Column(sa.Integer, primary_key=True)
+    service_id = sa.Column(sa.Integer, nullable=True)
 
     # FIXME(sbauza: Host field is nullable because some old Juno compute nodes
     # can still report stats from an old ResourceTracker without setting this
     # field.
     # This field has to be set non-nullable in a later cycle (probably Lxxx)
     # once we are sure that all compute nodes in production report it.
-    host = Column(String(255), nullable=True)
-    uuid = Column(String(36), nullable=True)
-    vcpus = Column(Integer, nullable=False)
-    memory_mb = Column(Integer, nullable=False)
-    local_gb = Column(Integer, nullable=False)
-    vcpus_used = Column(Integer, nullable=False)
-    memory_mb_used = Column(Integer, nullable=False)
-    local_gb_used = Column(Integer, nullable=False)
-    hypervisor_type = Column(MediumText(), nullable=False)
-    hypervisor_version = Column(Integer, nullable=False)
-    hypervisor_hostname = Column(String(255))
+    host = sa.Column(sa.String(255), nullable=True)
+    uuid = sa.Column(sa.String(36), nullable=True)
+    vcpus = sa.Column(sa.Integer, nullable=False)
+    memory_mb = sa.Column(sa.Integer, nullable=False)
+    local_gb = sa.Column(sa.Integer, nullable=False)
+    vcpus_used = sa.Column(sa.Integer, nullable=False)
+    memory_mb_used = sa.Column(sa.Integer, nullable=False)
+    local_gb_used = sa.Column(sa.Integer, nullable=False)
+    hypervisor_type = sa.Column(MediumText(), nullable=False)
+    hypervisor_version = sa.Column(sa.Integer, nullable=False)
+    hypervisor_hostname = sa.Column(sa.String(255))
 
     # Free Ram, amount of activity (resize, migration, boot, etc) and
     # the number of running VM's are a good starting point for what's
     # important when making scheduling decisions.
-    free_ram_mb = Column(Integer)
-    free_disk_gb = Column(Integer)
-    current_workload = Column(Integer)
-    running_vms = Column(Integer)
+    free_ram_mb = sa.Column(sa.Integer)
+    free_disk_gb = sa.Column(sa.Integer)
+    current_workload = sa.Column(sa.Integer)
+    running_vms = sa.Column(sa.Integer)
 
     # Note(masumotok): Expected Strings example:
     #
@@ -155,77 +155,79 @@ class ComputeNode(BASE, NovaBase, models.SoftDeleteMixin):
     # Points are "json translatable" and it must have all dictionary keys
     # above, since it is copied from <cpu> tag of getCapabilities()
     # (See libvirt.virtConnection).
-    cpu_info = Column(MediumText(), nullable=False)
-    disk_available_least = Column(Integer)
-    host_ip = Column(types.IPAddress())
-    supported_instances = Column(Text)
-    metrics = Column(Text)
+    cpu_info = sa.Column(MediumText(), nullable=False)
+    disk_available_least = sa.Column(sa.Integer)
+    host_ip = sa.Column(types.IPAddress())
+    supported_instances = sa.Column(sa.Text)
+    metrics = sa.Column(sa.Text)
 
     # Note(yongli): json string PCI Stats
     # '[{"vendor_id":"8086", "product_id":"1234", "count":3 }, ...]'
-    pci_stats = Column(Text)
+    pci_stats = sa.Column(sa.Text)
 
     # extra_resources is a json string containing arbitrary
     # data about additional resources.
-    extra_resources = Column(Text)
+    extra_resources = sa.Column(sa.Text)
 
     # json-encode string containing compute node statistics
-    stats = Column(Text, default='{}')
+    stats = sa.Column(sa.Text, default='{}')
 
     # json-encoded dict that contains NUMA topology as generated by
     # objects.NUMATopology._to_json()
-    numa_topology = Column(Text)
+    numa_topology = sa.Column(sa.Text)
 
     # allocation ratios provided by the RT
-    ram_allocation_ratio = Column(Float, nullable=True)
-    cpu_allocation_ratio = Column(Float, nullable=True)
-    disk_allocation_ratio = Column(Float, nullable=True)
-    mapped = Column(Integer, nullable=True, default=0)
+    ram_allocation_ratio = sa.Column(sa.Float, nullable=True)
+    cpu_allocation_ratio = sa.Column(sa.Float, nullable=True)
+    disk_allocation_ratio = sa.Column(sa.Float, nullable=True)
+    mapped = sa.Column(sa.Integer, nullable=True, default=0)
 
 
 class Certificate(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents a x509 certificate."""
     __tablename__ = 'certificates'
     __table_args__ = (
-        Index('certificates_project_id_deleted_idx', 'project_id', 'deleted'),
-        Index('certificates_user_id_deleted_idx', 'user_id', 'deleted')
+        sa.Index(
+            'certificates_project_id_deleted_idx', 'project_id', 'deleted',
+        ),
+        sa.Index('certificates_user_id_deleted_idx', 'user_id', 'deleted')
     )
-    id = Column(Integer, primary_key=True)
+    id = sa.Column(sa.Integer, primary_key=True)
 
-    user_id = Column(String(255))
-    project_id = Column(String(255))
-    file_name = Column(String(255))
+    user_id = sa.Column(sa.String(255))
+    project_id = sa.Column(sa.String(255))
+    file_name = sa.Column(sa.String(255))
 
 
 class Instance(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents a guest VM."""
     __tablename__ = 'instances'
     __table_args__ = (
-        Index('uuid', 'uuid', unique=True),
-        Index('instances_project_id_idx', 'project_id'),
-        Index('instances_project_id_deleted_idx',
+        sa.Index('uuid', 'uuid', unique=True),
+        sa.Index('instances_project_id_idx', 'project_id'),
+        sa.Index('instances_project_id_deleted_idx',
               'project_id', 'deleted'),
-        Index('instances_reservation_id_idx',
+        sa.Index('instances_reservation_id_idx',
               'reservation_id'),
-        Index('instances_terminated_at_launched_at_idx',
+        sa.Index('instances_terminated_at_launched_at_idx',
               'terminated_at', 'launched_at'),
-        Index('instances_uuid_deleted_idx',
+        sa.Index('instances_uuid_deleted_idx',
               'uuid', 'deleted'),
-        Index('instances_task_state_updated_at_idx',
+        sa.Index('instances_task_state_updated_at_idx',
               'task_state', 'updated_at'),
-        Index('instances_host_node_deleted_idx',
+        sa.Index('instances_host_node_deleted_idx',
               'host', 'node', 'deleted'),
-        Index('instances_host_deleted_cleaned_idx',
+        sa.Index('instances_host_deleted_cleaned_idx',
               'host', 'deleted', 'cleaned'),
-        Index('instances_deleted_created_at_idx',
+        sa.Index('instances_deleted_created_at_idx',
               'deleted', 'created_at'),
-        Index('instances_updated_at_project_id_idx',
+        sa.Index('instances_updated_at_project_id_idx',
               'updated_at', 'project_id'),
         schema.UniqueConstraint('uuid', name='uniq_instances0uuid'),
     )
     injected_files = []
 
-    id = Column(Integer, primary_key=True, autoincrement=True)
+    id = sa.Column(sa.Integer, primary_key=True, autoincrement=True)
 
     @property
     def name(self):
@@ -253,106 +255,107 @@ class Instance(BASE, NovaBase, models.SoftDeleteMixin):
     def _extra_keys(self):
         return ['name']
 
-    user_id = Column(String(255))
-    project_id = Column(String(255))
+    user_id = sa.Column(sa.String(255))
+    project_id = sa.Column(sa.String(255))
 
-    image_ref = Column(String(255))
-    kernel_id = Column(String(255))
-    ramdisk_id = Column(String(255))
-    hostname = Column(String(255))
+    image_ref = sa.Column(sa.String(255))
+    kernel_id = sa.Column(sa.String(255))
+    ramdisk_id = sa.Column(sa.String(255))
+    hostname = sa.Column(sa.String(255))
 
-    launch_index = Column(Integer)
-    key_name = Column(String(255))
-    key_data = Column(MediumText())
+    launch_index = sa.Column(sa.Integer)
+    key_name = sa.Column(sa.String(255))
+    key_data = sa.Column(MediumText())
 
-    power_state = Column(Integer)
-    vm_state = Column(String(255))
-    task_state = Column(String(255))
+    power_state = sa.Column(sa.Integer)
+    vm_state = sa.Column(sa.String(255))
+    task_state = sa.Column(sa.String(255))
 
-    memory_mb = Column(Integer)
-    vcpus = Column(Integer)
-    root_gb = Column(Integer)
-    ephemeral_gb = Column(Integer)
-    ephemeral_key_uuid = Column(String(36))
+    memory_mb = sa.Column(sa.Integer)
+    vcpus = sa.Column(sa.Integer)
+    root_gb = sa.Column(sa.Integer)
+    ephemeral_gb = sa.Column(sa.Integer)
+    ephemeral_key_uuid = sa.Column(sa.String(36))
 
     # This is not related to hostname, above.  It refers
     #  to the nova node.
-    host = Column(String(255))
+    host = sa.Column(sa.String(255))
     # To identify the "ComputeNode" which the instance resides in.
     # This equals to ComputeNode.hypervisor_hostname.
-    node = Column(String(255))
+    node = sa.Column(sa.String(255))
 
     # *not* flavorid, this is the internal primary_key
-    instance_type_id = Column(Integer)
+    instance_type_id = sa.Column(sa.Integer)
 
-    user_data = Column(MediumText())
+    user_data = sa.Column(MediumText())
 
-    reservation_id = Column(String(255))
+    reservation_id = sa.Column(sa.String(255))
 
-    launched_at = Column(DateTime)
-    terminated_at = Column(DateTime)
+    launched_at = sa.Column(sa.DateTime)
+    terminated_at = sa.Column(sa.DateTime)
 
     # This always refers to the availability_zone kwarg passed in /servers and
     # provided as an API option, not at all related to the host AZ the instance
     # belongs to.
-    availability_zone = Column(String(255))
+    availability_zone = sa.Column(sa.String(255))
 
     # User editable field for display in user-facing UIs
-    display_name = Column(String(255))
-    display_description = Column(String(255))
+    display_name = sa.Column(sa.String(255))
+    display_description = sa.Column(sa.String(255))
 
     # To remember on which host an instance booted.
     # An instance may have moved to another host by live migration.
-    launched_on = Column(MediumText())
+    launched_on = sa.Column(MediumText())
 
     # locked is superseded by locked_by and locked is not really
     # necessary but still used in API code so it remains.
-    locked = Column(Boolean)
-    locked_by = Column(Enum('owner', 'admin', name='instances0locked_by'))
+    locked = sa.Column(sa.Boolean)
+    locked_by = sa.Column(
+        sa.Enum('owner', 'admin', name='instances0locked_by'))
 
-    os_type = Column(String(255))
-    architecture = Column(String(255))
-    vm_mode = Column(String(255))
-    uuid = Column(String(36), nullable=False)
+    os_type = sa.Column(sa.String(255))
+    architecture = sa.Column(sa.String(255))
+    vm_mode = sa.Column(sa.String(255))
+    uuid = sa.Column(sa.String(36), nullable=False)
 
-    root_device_name = Column(String(255))
-    default_ephemeral_device = Column(String(255))
-    default_swap_device = Column(String(255))
-    config_drive = Column(String(255))
+    root_device_name = sa.Column(sa.String(255))
+    default_ephemeral_device = sa.Column(sa.String(255))
+    default_swap_device = sa.Column(sa.String(255))
+    config_drive = sa.Column(sa.String(255))
 
     # User editable field meant to represent what ip should be used
     # to connect to the instance
-    access_ip_v4 = Column(types.IPAddress())
-    access_ip_v6 = Column(types.IPAddress())
+    access_ip_v4 = sa.Column(types.IPAddress())
+    access_ip_v6 = sa.Column(types.IPAddress())
 
-    auto_disk_config = Column(Boolean())
-    progress = Column(Integer)
+    auto_disk_config = sa.Column(sa.Boolean())
+    progress = sa.Column(sa.Integer)
 
     # EC2 instance_initiated_shutdown_terminate
     # True: -> 'terminate'
     # False: -> 'stop'
     # Note(maoy): currently Nova will always stop instead of terminate
     # no matter what the flag says. So we set the default to False.
-    shutdown_terminate = Column(Boolean(), default=False)
+    shutdown_terminate = sa.Column(sa.Boolean(), default=False)
 
     # EC2 disable_api_termination
-    disable_terminate = Column(Boolean(), default=False)
+    disable_terminate = sa.Column(sa.Boolean(), default=False)
 
     # OpenStack compute cell name.  This will only be set at the top of
     # the cells tree and it'll be a full cell name such as 'api!hop1!hop2'
     # TODO(stephenfin): Remove this
-    cell_name = Column(String(255))
+    cell_name = sa.Column(sa.String(255))
 
     # NOTE(pumaranikar): internal_id attribute is no longer used (bug 1441242)
     # Hence, removing from object layer in current release (Ocata) and will
     # treated as deprecated. The column can be removed from schema with
     # a migration at the start of next release.
-    # internal_id = Column(Integer)
+    # internal_id = sa.Column(sa.Integer)
 
     # Records whether an instance has been deleted from disk
-    cleaned = Column(Integer, default=0)
+    cleaned = sa.Column(sa.Integer, default=0)
 
-    hidden = Column(Boolean, default=False)
+    hidden = sa.Column(sa.Boolean, default=False)
 
 
 class InstanceInfoCache(BASE, NovaBase, models.SoftDeleteMixin):
@@ -363,12 +366,12 @@ class InstanceInfoCache(BASE, NovaBase, models.SoftDeleteMixin):
         schema.UniqueConstraint(
             "instance_uuid",
             name="uniq_instance_info_caches0instance_uuid"),)
-    id = Column(Integer, primary_key=True, autoincrement=True)
+    id = sa.Column(sa.Integer, primary_key=True, autoincrement=True)
 
     # text column used for storing a json object of network data for api
-    network_info = Column(MediumText())
+    network_info = sa.Column(MediumText())
 
-    instance_uuid = Column(String(36), ForeignKey('instances.uuid'),
+    instance_uuid = sa.Column(sa.String(36), sa.ForeignKey('instances.uuid'),
                            nullable=False)
     instance = orm.relationship(Instance,
                             backref=orm.backref('info_cache', uselist=False),
@@ -379,21 +382,21 @@ class InstanceInfoCache(BASE, NovaBase, models.SoftDeleteMixin):
 class InstanceExtra(BASE, NovaBase, models.SoftDeleteMixin):
     __tablename__ = 'instance_extra'
     __table_args__ = (
-        Index('instance_extra_idx', 'instance_uuid'),)
-    id = Column(Integer, primary_key=True, autoincrement=True)
-    instance_uuid = Column(String(36), ForeignKey('instances.uuid'),
+        sa.Index('instance_extra_idx', 'instance_uuid'),)
+    id = sa.Column(sa.Integer, primary_key=True, autoincrement=True)
+    instance_uuid = sa.Column(sa.String(36), sa.ForeignKey('instances.uuid'),
                            nullable=False)
-    device_metadata = orm.deferred(Column(Text))
-    numa_topology = orm.deferred(Column(Text))
-    pci_requests = orm.deferred(Column(Text))
-    flavor = orm.deferred(Column(Text))
-    vcpu_model = orm.deferred(Column(Text))
-    migration_context = orm.deferred(Column(Text))
-    keypairs = orm.deferred(Column(Text))
-    trusted_certs = orm.deferred(Column(Text))
+    device_metadata = orm.deferred(sa.Column(sa.Text))
+    numa_topology = orm.deferred(sa.Column(sa.Text))
+    pci_requests = orm.deferred(sa.Column(sa.Text))
+    flavor = orm.deferred(sa.Column(sa.Text))
+    vcpu_model = orm.deferred(sa.Column(sa.Text))
+    migration_context = orm.deferred(sa.Column(sa.Text))
+    keypairs = orm.deferred(sa.Column(sa.Text))
+    trusted_certs = orm.deferred(sa.Column(sa.Text))
     # NOTE(Luyao): 'vpmems' is still in the database
     # and can be removed in the future release.
-    resources = orm.deferred(Column(Text))
+    resources = orm.deferred(sa.Column(sa.Text))
     instance = orm.relationship(Instance,
                             backref=orm.backref('extra',
                                                 uselist=False),
@@ -419,19 +422,19 @@ class InstanceTypes(BASE, NovaBase, models.SoftDeleteMixin):
     )
 
     # Internal only primary key/id
-    id = Column(Integer, primary_key=True)
-    name = Column(String(255))
-    memory_mb = Column(Integer, nullable=False)
-    vcpus = Column(Integer, nullable=False)
-    root_gb = Column(Integer)
-    ephemeral_gb = Column(Integer)
+    id = sa.Column(sa.Integer, primary_key=True)
+    name = sa.Column(sa.String(255))
+    memory_mb = sa.Column(sa.Integer, nullable=False)
+    vcpus = sa.Column(sa.Integer, nullable=False)
+    root_gb = sa.Column(sa.Integer)
+    ephemeral_gb = sa.Column(sa.Integer)
     # Public facing id will be renamed public_id
-    flavorid = Column(String(255))
-    swap = Column(Integer, nullable=False, default=0)
-    rxtx_factor = Column(Float, default=1)
-    vcpu_weight = Column(Integer)
-    disabled = Column(Boolean, default=False)
-    is_public = Column(Boolean, default=True)
+    flavorid = sa.Column(sa.String(255))
+    swap = sa.Column(sa.Integer, nullable=False, default=0)
+    rxtx_factor = sa.Column(sa.Float, default=1)
+    vcpu_weight = sa.Column(sa.Integer)
+    disabled = sa.Column(sa.Boolean, default=False)
+    is_public = sa.Column(sa.Boolean, default=True)
 
 
 class Quota(BASE, NovaBase, models.SoftDeleteMixin):
@@ -450,12 +453,12 @@ class Quota(BASE, NovaBase, models.SoftDeleteMixin):
         name="uniq_quotas0project_id0resource0deleted"
         ),
     )
-    id = Column(Integer, primary_key=True)
+    id = sa.Column(sa.Integer, primary_key=True)
 
-    project_id = Column(String(255))
+    project_id = sa.Column(sa.String(255))
 
-    resource = Column(String(255), nullable=False)
-    hard_limit = Column(Integer)
+    resource = sa.Column(sa.String(255), nullable=False)
+    hard_limit = sa.Column(sa.Integer)
 
 
 class ProjectUserQuota(BASE, NovaBase, models.SoftDeleteMixin):
@@ -466,18 +469,18 @@ class ProjectUserQuota(BASE, NovaBase, models.SoftDeleteMixin):
     __table_args__ = (
         schema.UniqueConstraint("user_id", "project_id", "resource", "deleted",
                                 name=uniq_name),
-        Index('project_user_quotas_project_id_deleted_idx',
+        sa.Index('project_user_quotas_project_id_deleted_idx',
               'project_id', 'deleted'),
-        Index('project_user_quotas_user_id_deleted_idx',
+        sa.Index('project_user_quotas_user_id_deleted_idx',
               'user_id', 'deleted')
     )
-    id = Column(Integer, primary_key=True, nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
 
-    project_id = Column(String(255), nullable=False)
-    user_id = Column(String(255), nullable=False)
+    project_id = sa.Column(sa.String(255), nullable=False)
+    user_id = sa.Column(sa.String(255), nullable=False)
 
-    resource = Column(String(255), nullable=False)
-    hard_limit = Column(Integer)
+    resource = sa.Column(sa.String(255), nullable=False)
+    hard_limit = sa.Column(sa.Integer)
 
 
 class QuotaClass(BASE, NovaBase, models.SoftDeleteMixin):
@@ -490,14 +493,14 @@ class QuotaClass(BASE, NovaBase, models.SoftDeleteMixin):
 
     __tablename__ = 'quota_classes'
     __table_args__ = (
-        Index('ix_quota_classes_class_name', 'class_name'),
+        sa.Index('ix_quota_classes_class_name', 'class_name'),
     )
-    id = Column(Integer, primary_key=True)
+    id = sa.Column(sa.Integer, primary_key=True)
 
-    class_name = Column(String(255))
+    class_name = sa.Column(sa.String(255))
 
-    resource = Column(String(255))
-    hard_limit = Column(Integer)
+    resource = sa.Column(sa.String(255))
+    hard_limit = sa.Column(sa.Integer)
 
 
 class QuotaUsage(BASE, NovaBase, models.SoftDeleteMixin):
@@ -505,23 +508,23 @@ class QuotaUsage(BASE, NovaBase, models.SoftDeleteMixin):
 
     __tablename__ = 'quota_usages'
     __table_args__ = (
-        Index('ix_quota_usages_project_id', 'project_id'),
-        Index('ix_quota_usages_user_id_deleted', 'user_id', 'deleted'),
+        sa.Index('ix_quota_usages_project_id', 'project_id'),
+        sa.Index('ix_quota_usages_user_id_deleted', 'user_id', 'deleted'),
     )
-    id = Column(Integer, primary_key=True)
+    id = sa.Column(sa.Integer, primary_key=True)
 
-    project_id = Column(String(255))
-    user_id = Column(String(255))
-    resource = Column(String(255), nullable=False)
+    project_id = sa.Column(sa.String(255))
+    user_id = sa.Column(sa.String(255))
+    resource = sa.Column(sa.String(255), nullable=False)
 
-    in_use = Column(Integer, nullable=False)
-    reserved = Column(Integer, nullable=False)
+    in_use = sa.Column(sa.Integer, nullable=False)
+    reserved = sa.Column(sa.Integer, nullable=False)
 
     @property
     def total(self):
         return self.in_use + self.reserved
 
-    until_refresh = Column(Integer)
+    until_refresh = sa.Column(sa.Integer)
 
 
 class Reservation(BASE, NovaBase, models.SoftDeleteMixin):
@@ -529,22 +532,23 @@ class Reservation(BASE, NovaBase, models.SoftDeleteMixin):
 
     __tablename__ = 'reservations'
     __table_args__ = (
-        Index('ix_reservations_project_id', 'project_id'),
-        Index('reservations_uuid_idx', 'uuid'),
-        Index('reservations_deleted_expire_idx', 'deleted', 'expire'),
-        Index('ix_reservations_user_id_deleted', 'user_id', 'deleted'),
+        sa.Index('ix_reservations_project_id', 'project_id'),
+        sa.Index('reservations_uuid_idx', 'uuid'),
+        sa.Index('reservations_deleted_expire_idx', 'deleted', 'expire'),
+        sa.Index('ix_reservations_user_id_deleted', 'user_id', 'deleted'),
     )
-    id = Column(Integer, primary_key=True, nullable=False)
-    uuid = Column(String(36), nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    uuid = sa.Column(sa.String(36), nullable=False)
 
-    usage_id = Column(Integer, ForeignKey('quota_usages.id'), nullable=False)
+    usage_id = sa.Column(
+        sa.Integer, sa.ForeignKey('quota_usages.id'), nullable=False)
 
-    project_id = Column(String(255))
-    user_id = Column(String(255))
-    resource = Column(String(255))
+    project_id = sa.Column(sa.String(255))
+    user_id = sa.Column(sa.String(255))
+    resource = sa.Column(sa.String(255))
 
-    delta = Column(Integer, nullable=False)
-    expire = Column(DateTime)
+    delta = sa.Column(sa.Integer, nullable=False)
+    expire = sa.Column(sa.DateTime)
 
     usage = orm.relationship(
         "QuotaUsage",
@@ -559,49 +563,49 @@ class Snapshot(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents a block storage device that can be attached to a VM."""
     __tablename__ = 'snapshots'
     __table_args__ = ()
-    id = Column(String(36), primary_key=True, nullable=False)
-    deleted = Column(String(36), default="")
+    id = sa.Column(sa.String(36), primary_key=True, nullable=False)
+    deleted = sa.Column(sa.String(36), default="")
 
     @property
     def volume_name(self):
         return CONF.volume_name_template % self.volume_id
 
-    user_id = Column(String(255))
-    project_id = Column(String(255))
+    user_id = sa.Column(sa.String(255))
+    project_id = sa.Column(sa.String(255))
 
-    volume_id = Column(String(36), nullable=False)
-    status = Column(String(255))
-    progress = Column(String(255))
-    volume_size = Column(Integer)
-    scheduled_at = Column(DateTime)
+    volume_id = sa.Column(sa.String(36), nullable=False)
+    status = sa.Column(sa.String(255))
+    progress = sa.Column(sa.String(255))
+    volume_size = sa.Column(sa.Integer)
+    scheduled_at = sa.Column(sa.DateTime)
 
-    display_name = Column(String(255))
-    display_description = Column(String(255))
+    display_name = sa.Column(sa.String(255))
+    display_description = sa.Column(sa.String(255))
 
 
 class BlockDeviceMapping(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents block device mapping that is defined by EC2."""
     __tablename__ = "block_device_mapping"
     __table_args__ = (
-        Index('snapshot_id', 'snapshot_id'),
-        Index('volume_id', 'volume_id'),
-        Index('block_device_mapping_instance_uuid_device_name_idx',
+        sa.Index('snapshot_id', 'snapshot_id'),
+        sa.Index('volume_id', 'volume_id'),
+        sa.Index('block_device_mapping_instance_uuid_device_name_idx',
               'instance_uuid', 'device_name'),
-        Index('block_device_mapping_instance_uuid_volume_id_idx',
+        sa.Index('block_device_mapping_instance_uuid_volume_id_idx',
               'instance_uuid', 'volume_id'),
-        Index('block_device_mapping_instance_uuid_idx', 'instance_uuid'),
+        sa.Index('block_device_mapping_instance_uuid_idx', 'instance_uuid'),
         schema.UniqueConstraint('uuid', name='uniq_block_device_mapping0uuid'),
     )
-    id = Column(Integer, primary_key=True, autoincrement=True)
+    id = sa.Column(sa.Integer, primary_key=True, autoincrement=True)
 
-    instance_uuid = Column(String(36), ForeignKey('instances.uuid'))
+    instance_uuid = sa.Column(sa.String(36), sa.ForeignKey('instances.uuid'))
     # NOTE(mdbooth): The REST API for BDMs includes a UUID field. That uuid
     # refers to an image, volume, or snapshot which will be used in the
     # initialisation of the BDM. It is only relevant during the API call, and
     # is not persisted directly. This is the UUID of the BDM itself.
     # FIXME(danms): This should eventually be non-nullable, but we need a
     # transition period first.
-    uuid = Column(String(36))
+    uuid = sa.Column(sa.String(36))
     instance = orm.relationship(Instance,
                             backref=orm.backref('block_device_mapping'),
                             foreign_keys=instance_uuid,
@@ -611,51 +615,52 @@ class BlockDeviceMapping(BASE, NovaBase, models.SoftDeleteMixin):
                                               'BlockDeviceMapping.deleted=='
                                               '0)')
 
-    source_type = Column(String(255))
-    destination_type = Column(String(255))
-    guest_format = Column(String(255))
-    device_type = Column(String(255))
-    disk_bus = Column(String(255))
+    source_type = sa.Column(sa.String(255))
+    destination_type = sa.Column(sa.String(255))
+    guest_format = sa.Column(sa.String(255))
+    device_type = sa.Column(sa.String(255))
+    disk_bus = sa.Column(sa.String(255))
 
-    boot_index = Column(Integer)
+    boot_index = sa.Column(sa.Integer)
 
-    device_name = Column(String(255))
+    device_name = sa.Column(sa.String(255))
 
     # default=False for compatibility of the existing code.
     # With EC2 API,
     # default True for ami specified device.
     # default False for created with other timing.
     # TODO(sshturm) add default in db
-    delete_on_termination = Column(Boolean, default=False)
+    delete_on_termination = sa.Column(sa.Boolean, default=False)
 
-    snapshot_id = Column(String(36))
+    snapshot_id = sa.Column(sa.String(36))
 
-    volume_id = Column(String(36))
-    volume_size = Column(Integer)
+    volume_id = sa.Column(sa.String(36))
+    volume_size = sa.Column(sa.Integer)
 
-    volume_type = Column(String(255))
+    volume_type = sa.Column(sa.String(255))
 
-    image_id = Column(String(36))
+    image_id = sa.Column(sa.String(36))
 
     # for no device to suppress devices.
-    no_device = Column(Boolean)
+    no_device = sa.Column(sa.Boolean)
 
-    connection_info = Column(MediumText())
+    connection_info = sa.Column(MediumText())
 
-    tag = Column(String(255))
+    tag = sa.Column(sa.String(255))
 
-    attachment_id = Column(String(36))
+    attachment_id = sa.Column(sa.String(36))
 
 
 class SecurityGroupInstanceAssociation(BASE, NovaBase, models.SoftDeleteMixin):
     __tablename__ = 'security_group_instance_association'
     __table_args__ = (
-        Index('security_group_instance_association_instance_uuid_idx',
+        sa.Index('security_group_instance_association_instance_uuid_idx',
               'instance_uuid'),
     )
-    id = Column(Integer, primary_key=True, nullable=False)
-    security_group_id = Column(Integer, ForeignKey('security_groups.id'))
-    instance_uuid = Column(String(36), ForeignKey('instances.uuid'))
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    security_group_id = sa.Column(
+        sa.Integer, sa.ForeignKey('security_groups.id'))
+    instance_uuid = sa.Column(sa.String(36), sa.ForeignKey('instances.uuid'))
 
 
 class SecurityGroup(BASE, NovaBase, models.SoftDeleteMixin):
@@ -666,12 +671,12 @@ class SecurityGroup(BASE, NovaBase, models.SoftDeleteMixin):
                                 name='uniq_security_groups0project_id0'
                                      'name0deleted'),
     )
-    id = Column(Integer, primary_key=True)
+    id = sa.Column(sa.Integer, primary_key=True)
 
-    name = Column(String(255))
-    description = Column(String(255))
-    user_id = Column(String(255))
-    project_id = Column(String(255))
+    name = sa.Column(sa.String(255))
+    description = sa.Column(sa.String(255))
+    user_id = sa.Column(sa.String(255))
+    project_id = sa.Column(sa.String(255))
 
     instances = orm.relationship(Instance,
                              secondary="security_group_instance_association",
@@ -695,23 +700,24 @@ class SecurityGroupIngressRule(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents a rule in a security group."""
     __tablename__ = 'security_group_rules'
     __table_args__ = ()
-    id = Column(Integer, primary_key=True)
+    id = sa.Column(sa.Integer, primary_key=True)
 
-    parent_group_id = Column(Integer, ForeignKey('security_groups.id'))
+    parent_group_id = sa.Column(
+        sa.Integer, sa.ForeignKey('security_groups.id'))
     parent_group = orm.relationship("SecurityGroup", backref="rules",
                                 foreign_keys=parent_group_id,
                                 primaryjoin='and_('
         'SecurityGroupIngressRule.parent_group_id == SecurityGroup.id,'
         'SecurityGroupIngressRule.deleted == 0)')
 
-    protocol = Column(String(255))
-    from_port = Column(Integer)
-    to_port = Column(Integer)
-    cidr = Column(types.CIDR())
+    protocol = sa.Column(sa.String(255))
+    from_port = sa.Column(sa.Integer)
+    to_port = sa.Column(sa.Integer)
+    cidr = sa.Column(types.CIDR())
 
     # Note: This is not the parent SecurityGroup. It's SecurityGroup we're
     # granting access for.
-    group_id = Column(Integer, ForeignKey('security_groups.id'))
+    group_id = sa.Column(sa.Integer, sa.ForeignKey('security_groups.id'))
     grantee_group = orm.relationship("SecurityGroup",
                                  foreign_keys=group_id,
                                  primaryjoin='and_('
@@ -724,11 +730,11 @@ class SecurityGroupIngressRule(BASE, NovaBase, models.SoftDeleteMixin):
 class SecurityGroupIngressDefaultRule(BASE, NovaBase, models.SoftDeleteMixin):
     __tablename__ = 'security_group_default_rules'
     __table_args__ = ()
-    id = Column(Integer, primary_key=True, nullable=False)
-    protocol = Column(String(5))  # "tcp", "udp" or "icmp"
-    from_port = Column(Integer)
-    to_port = Column(Integer)
-    cidr = Column(types.CIDR())
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    protocol = sa.Column(sa.String(5))  # "tcp", "udp" or "icmp"
+    from_port = sa.Column(sa.Integer)
+    to_port = sa.Column(sa.Integer)
+    cidr = sa.Column(types.CIDR())
 
 
 # TODO(stephenfin): Remove this in the V release or later, once we're sure we
@@ -737,12 +743,12 @@ class ProviderFirewallRule(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents a rule in a security group."""
     __tablename__ = 'provider_fw_rules'
     __table_args__ = ()
-    id = Column(Integer, primary_key=True, nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
 
-    protocol = Column(String(5))  # "tcp", "udp", or "icmp"
-    from_port = Column(Integer)
-    to_port = Column(Integer)
-    cidr = Column(types.CIDR())
+    protocol = sa.Column(sa.String(5))  # "tcp", "udp", or "icmp"
+    from_port = sa.Column(sa.Integer)
+    to_port = sa.Column(sa.Integer)
+    cidr = sa.Column(types.CIDR())
 
 
 # NOTE(alaski): This table exists in the nova_api database and its usage here
@@ -754,15 +760,15 @@ class KeyPair(BASE, NovaBase, models.SoftDeleteMixin):
         schema.UniqueConstraint("user_id", "name", "deleted",
                                 name="uniq_key_pairs0user_id0name0deleted"),
     )
-    id = Column(Integer, primary_key=True, nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
 
-    name = Column(String(255), nullable=False)
+    name = sa.Column(sa.String(255), nullable=False)
 
-    user_id = Column(String(255))
+    user_id = sa.Column(sa.String(255))
 
-    fingerprint = Column(String(255))
-    public_key = Column(MediumText())
-    type = Column(Enum('ssh', 'x509', name='keypair_types'),
+    fingerprint = sa.Column(sa.String(255))
+    public_key = sa.Column(MediumText())
+    type = sa.Column(sa.Enum('ssh', 'x509', name='keypair_types'),
                   nullable=False, server_default='ssh')
 
 
@@ -770,43 +776,43 @@ class Migration(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents a running host-to-host migration."""
     __tablename__ = 'migrations'
     __table_args__ = (
-        Index('migrations_instance_uuid_and_status_idx', 'deleted',
+        sa.Index('migrations_instance_uuid_and_status_idx', 'deleted',
               'instance_uuid', 'status'),
-        Index('migrations_by_host_nodes_and_status_idx', 'deleted',
+        sa.Index('migrations_by_host_nodes_and_status_idx', 'deleted',
               'source_compute', 'dest_compute', 'source_node', 'dest_node',
               'status'),
-        Index('migrations_uuid', 'uuid', unique=True),
-        Index('migrations_updated_at_idx', 'updated_at'),
+        sa.Index('migrations_uuid', 'uuid', unique=True),
+        sa.Index('migrations_updated_at_idx', 'updated_at'),
     )
-    id = Column(Integer, primary_key=True, nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
     # NOTE(tr3buchet): the ____compute variables are instance['host']
-    source_compute = Column(String(255))
-    dest_compute = Column(String(255))
+    source_compute = sa.Column(sa.String(255))
+    dest_compute = sa.Column(sa.String(255))
     # nodes are equivalent to a compute node's 'hypervisor_hostname'
-    source_node = Column(String(255))
-    dest_node = Column(String(255))
+    source_node = sa.Column(sa.String(255))
+    dest_node = sa.Column(sa.String(255))
     # NOTE(tr3buchet): dest_host, btw, is an ip address
-    dest_host = Column(String(255))
-    old_instance_type_id = Column(Integer())
-    new_instance_type_id = Column(Integer())
-    instance_uuid = Column(String(36), ForeignKey('instances.uuid'))
-    uuid = Column(String(36), nullable=True)
+    dest_host = sa.Column(sa.String(255))
+    old_instance_type_id = sa.Column(sa.Integer())
+    new_instance_type_id = sa.Column(sa.Integer())
+    instance_uuid = sa.Column(sa.String(36), sa.ForeignKey('instances.uuid'))
+    uuid = sa.Column(sa.String(36), nullable=True)
     # TODO(_cerberus_): enum
-    status = Column(String(255))
-    migration_type = Column(Enum('migration', 'resize', 'live-migration',
+    status = sa.Column(sa.String(255))
+    migration_type = sa.Column(sa.Enum('migration', 'resize', 'live-migration',
                                  'evacuation', name='migration_type'),
                             nullable=True)
-    hidden = Column(Boolean, default=False)
-    memory_total = Column(BigInteger, nullable=True)
-    memory_processed = Column(BigInteger, nullable=True)
-    memory_remaining = Column(BigInteger, nullable=True)
-    disk_total = Column(BigInteger, nullable=True)
-    disk_processed = Column(BigInteger, nullable=True)
-    disk_remaining = Column(BigInteger, nullable=True)
-    cross_cell_move = Column(Boolean, default=False)
+    hidden = sa.Column(sa.Boolean, default=False)
+    memory_total = sa.Column(sa.BigInteger, nullable=True)
+    memory_processed = sa.Column(sa.BigInteger, nullable=True)
+    memory_remaining = sa.Column(sa.BigInteger, nullable=True)
+    disk_total = sa.Column(sa.BigInteger, nullable=True)
+    disk_processed = sa.Column(sa.BigInteger, nullable=True)
+    disk_remaining = sa.Column(sa.BigInteger, nullable=True)
+    cross_cell_move = sa.Column(sa.Boolean, default=False)
 
-    user_id = Column(String(255), nullable=True)
-    project_id = Column(String(255), nullable=True)
+    user_id = sa.Column(sa.String(255), nullable=True)
+    project_id = sa.Column(sa.String(255), nullable=True)
 
     instance = orm.relationship("Instance", foreign_keys=instance_uuid,
                             primaryjoin='and_(Migration.instance_uuid == '
@@ -822,50 +828,50 @@ class Network(BASE, NovaBase, models.SoftDeleteMixin):
     __table_args__ = (
         schema.UniqueConstraint("vlan", "deleted",
                                 name="uniq_networks0vlan0deleted"),
-       Index('networks_bridge_deleted_idx', 'bridge', 'deleted'),
-       Index('networks_host_idx', 'host'),
-       Index('networks_project_id_deleted_idx', 'project_id', 'deleted'),
-       Index('networks_uuid_project_id_deleted_idx', 'uuid',
+       sa.Index('networks_bridge_deleted_idx', 'bridge', 'deleted'),
+       sa.Index('networks_host_idx', 'host'),
+       sa.Index('networks_project_id_deleted_idx', 'project_id', 'deleted'),
+       sa.Index('networks_uuid_project_id_deleted_idx', 'uuid',
              'project_id', 'deleted'),
-       Index('networks_vlan_deleted_idx', 'vlan', 'deleted'),
-       Index('networks_cidr_v6_idx', 'cidr_v6')
+       sa.Index('networks_vlan_deleted_idx', 'vlan', 'deleted'),
+       sa.Index('networks_cidr_v6_idx', 'cidr_v6')
     )
 
-    id = Column(Integer, primary_key=True, nullable=False)
-    label = Column(String(255))
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    label = sa.Column(sa.String(255))
 
-    injected = Column(Boolean, default=False)
-    cidr = Column(types.CIDR())
-    cidr_v6 = Column(types.CIDR())
-    multi_host = Column(Boolean, default=False)
+    injected = sa.Column(sa.Boolean, default=False)
+    cidr = sa.Column(types.CIDR())
+    cidr_v6 = sa.Column(types.CIDR())
+    multi_host = sa.Column(sa.Boolean, default=False)
 
-    gateway_v6 = Column(types.IPAddress())
-    netmask_v6 = Column(types.IPAddress())
-    netmask = Column(types.IPAddress())
-    bridge = Column(String(255))
-    bridge_interface = Column(String(255))
-    gateway = Column(types.IPAddress())
-    broadcast = Column(types.IPAddress())
-    dns1 = Column(types.IPAddress())
-    dns2 = Column(types.IPAddress())
+    gateway_v6 = sa.Column(types.IPAddress())
+    netmask_v6 = sa.Column(types.IPAddress())
+    netmask = sa.Column(types.IPAddress())
+    bridge = sa.Column(sa.String(255))
+    bridge_interface = sa.Column(sa.String(255))
+    gateway = sa.Column(types.IPAddress())
+    broadcast = sa.Column(types.IPAddress())
+    dns1 = sa.Column(types.IPAddress())
+    dns2 = sa.Column(types.IPAddress())
 
-    vlan = Column(Integer)
-    vpn_public_address = Column(types.IPAddress())
-    vpn_public_port = Column(Integer)
-    vpn_private_address = Column(types.IPAddress())
-    dhcp_start = Column(types.IPAddress())
+    vlan = sa.Column(sa.Integer)
+    vpn_public_address = sa.Column(types.IPAddress())
+    vpn_public_port = sa.Column(sa.Integer)
+    vpn_private_address = sa.Column(types.IPAddress())
+    dhcp_start = sa.Column(types.IPAddress())
 
-    rxtx_base = Column(Integer)
+    rxtx_base = sa.Column(sa.Integer)
 
-    project_id = Column(String(255))
-    priority = Column(Integer)
-    host = Column(String(255))
-    uuid = Column(String(36))
+    project_id = sa.Column(sa.String(255))
+    priority = sa.Column(sa.Integer)
+    host = sa.Column(sa.String(255))
+    uuid = sa.Column(sa.String(36))
 
-    mtu = Column(Integer)
-    dhcp_server = Column(types.IPAddress())
-    enable_dhcp = Column(Boolean, default=True)
-    share_address = Column(Boolean, default=False)
+    mtu = sa.Column(sa.Integer)
+    dhcp_server = sa.Column(types.IPAddress())
+    enable_dhcp = sa.Column(sa.Boolean, default=True)
+    share_address = sa.Column(sa.Boolean, default=False)
 
 
 class VirtualInterface(BASE, NovaBase, models.SoftDeleteMixin):
@@ -874,16 +880,16 @@ class VirtualInterface(BASE, NovaBase, models.SoftDeleteMixin):
     __table_args__ = (
         schema.UniqueConstraint("address", "deleted",
                         name="uniq_virtual_interfaces0address0deleted"),
-        Index('virtual_interfaces_network_id_idx', 'network_id'),
-        Index('virtual_interfaces_instance_uuid_fkey', 'instance_uuid'),
-        Index('virtual_interfaces_uuid_idx', 'uuid'),
+        sa.Index('virtual_interfaces_network_id_idx', 'network_id'),
+        sa.Index('virtual_interfaces_instance_uuid_fkey', 'instance_uuid'),
+        sa.Index('virtual_interfaces_uuid_idx', 'uuid'),
     )
-    id = Column(Integer, primary_key=True, nullable=False)
-    address = Column(String(255))
-    network_id = Column(Integer)
-    instance_uuid = Column(String(36), ForeignKey('instances.uuid'))
-    uuid = Column(String(36))
-    tag = Column(String(255))
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    address = sa.Column(sa.String(255))
+    network_id = sa.Column(sa.Integer)
+    instance_uuid = sa.Column(sa.String(36), sa.ForeignKey('instances.uuid'))
+    uuid = sa.Column(sa.String(36))
+    tag = sa.Column(sa.String(255))
 
 
 # TODO(stephenfin): Remove this in the V release or later, once we're sure we
@@ -894,35 +900,36 @@ class FixedIp(BASE, NovaBase, models.SoftDeleteMixin):
     __table_args__ = (
         schema.UniqueConstraint(
             "address", "deleted", name="uniq_fixed_ips0address0deleted"),
-        Index('fixed_ips_virtual_interface_id_fkey', 'virtual_interface_id'),
-        Index('network_id', 'network_id'),
-        Index('address', 'address'),
-        Index('fixed_ips_instance_uuid_fkey', 'instance_uuid'),
-        Index('fixed_ips_host_idx', 'host'),
-        Index('fixed_ips_network_id_host_deleted_idx', 'network_id', 'host',
+        sa.Index(
+            'fixed_ips_virtual_interface_id_fkey', 'virtual_interface_id'),
+        sa.Index('network_id', 'network_id'),
+        sa.Index('address', 'address'),
+        sa.Index('fixed_ips_instance_uuid_fkey', 'instance_uuid'),
+        sa.Index('fixed_ips_host_idx', 'host'),
+        sa.Index('fixed_ips_network_id_host_deleted_idx', 'network_id', 'host',
               'deleted'),
-        Index('fixed_ips_address_reserved_network_id_deleted_idx',
+        sa.Index('fixed_ips_address_reserved_network_id_deleted_idx',
               'address', 'reserved', 'network_id', 'deleted'),
-        Index('fixed_ips_deleted_allocated_idx', 'address', 'deleted',
+        sa.Index('fixed_ips_deleted_allocated_idx', 'address', 'deleted',
               'allocated'),
-        Index('fixed_ips_deleted_allocated_updated_at_idx', 'deleted',
+        sa.Index('fixed_ips_deleted_allocated_updated_at_idx', 'deleted',
               'allocated', 'updated_at')
     )
-    id = Column(Integer, primary_key=True)
-    address = Column(types.IPAddress())
-    network_id = Column(Integer)
-    virtual_interface_id = Column(Integer)
-    instance_uuid = Column(String(36), ForeignKey('instances.uuid'))
+    id = sa.Column(sa.Integer, primary_key=True)
+    address = sa.Column(types.IPAddress())
+    network_id = sa.Column(sa.Integer)
+    virtual_interface_id = sa.Column(sa.Integer)
+    instance_uuid = sa.Column(sa.String(36), sa.ForeignKey('instances.uuid'))
     # associated means that a fixed_ip has its instance_id column set
     # allocated means that a fixed_ip has its virtual_interface_id column set
     # TODO(sshturm) add default in db
-    allocated = Column(Boolean, default=False)
+    allocated = sa.Column(sa.Boolean, default=False)
     # leased means dhcp bridge has leased the ip
     # TODO(sshturm) add default in db
-    leased = Column(Boolean, default=False)
+    leased = sa.Column(sa.Boolean, default=False)
     # TODO(sshturm) add default in db
-    reserved = Column(Boolean, default=False)
-    host = Column(String(255))
+    reserved = sa.Column(sa.Boolean, default=False)
+    host = sa.Column(sa.String(255))
     network = orm.relationship(Network,
                            backref=orm.backref('fixed_ips'),
                            foreign_keys=network_id,
@@ -954,21 +961,21 @@ class FloatingIp(BASE, NovaBase, models.SoftDeleteMixin):
     __table_args__ = (
         schema.UniqueConstraint("address", "deleted",
                                 name="uniq_floating_ips0address0deleted"),
-        Index('fixed_ip_id', 'fixed_ip_id'),
-        Index('floating_ips_host_idx', 'host'),
-        Index('floating_ips_project_id_idx', 'project_id'),
-        Index('floating_ips_pool_deleted_fixed_ip_id_project_id_idx',
+        sa.Index('fixed_ip_id', 'fixed_ip_id'),
+        sa.Index('floating_ips_host_idx', 'host'),
+        sa.Index('floating_ips_project_id_idx', 'project_id'),
+        sa.Index('floating_ips_pool_deleted_fixed_ip_id_project_id_idx',
               'pool', 'deleted', 'fixed_ip_id', 'project_id')
     )
-    id = Column(Integer, primary_key=True)
-    address = Column(types.IPAddress())
-    fixed_ip_id = Column(Integer)
-    project_id = Column(String(255))
-    host = Column(String(255))
-    auto_assigned = Column(Boolean, default=False)
+    id = sa.Column(sa.Integer, primary_key=True)
+    address = sa.Column(types.IPAddress())
+    fixed_ip_id = sa.Column(sa.Integer)
+    project_id = sa.Column(sa.String(255))
+    host = sa.Column(sa.String(255))
+    auto_assigned = sa.Column(sa.Boolean, default=False)
     # TODO(sshturm) add default in db
-    pool = Column(String(255))
-    interface = Column(String(255))
+    pool = sa.Column(sa.String(255))
+    interface = sa.Column(sa.String(255))
     fixed_ip = orm.relationship(FixedIp,
                             backref=orm.backref('floating_ips'),
                             foreign_keys=fixed_ip_id,
@@ -983,14 +990,14 @@ class DNSDomain(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents a DNS domain with availability zone or project info."""
     __tablename__ = 'dns_domains'
     __table_args__ = (
-        Index('dns_domains_project_id_idx', 'project_id'),
-        Index('dns_domains_domain_deleted_idx', 'domain', 'deleted'),
+        sa.Index('dns_domains_project_id_idx', 'project_id'),
+        sa.Index('dns_domains_domain_deleted_idx', 'domain', 'deleted'),
     )
-    deleted = Column(Boolean, default=False)
-    domain = Column(String(255), primary_key=True)
-    scope = Column(String(255))
-    availability_zone = Column(String(255))
-    project_id = Column(String(255))
+    deleted = sa.Column(sa.Boolean, default=False)
+    domain = sa.Column(sa.String(255), primary_key=True)
+    scope = sa.Column(sa.String(255))
+    availability_zone = sa.Column(sa.String(255))
+    project_id = sa.Column(sa.String(255))
 
 
 # TODO(stephenfin): Remove in V or later
@@ -1002,14 +1009,14 @@ class ConsolePool(BASE, NovaBase, models.SoftDeleteMixin):
             "host", "console_type", "compute_host", "deleted",
             name="uniq_console_pools0host0console_type0compute_host0deleted"),
     )
-    id = Column(Integer, primary_key=True)
-    address = Column(types.IPAddress())
-    username = Column(String(255))
-    password = Column(String(255))
-    console_type = Column(String(255))
-    public_hostname = Column(String(255))
-    host = Column(String(255))
-    compute_host = Column(String(255))
+    id = sa.Column(sa.Integer, primary_key=True)
+    address = sa.Column(types.IPAddress())
+    username = sa.Column(sa.String(255))
+    password = sa.Column(sa.String(255))
+    console_type = sa.Column(sa.String(255))
+    public_hostname = sa.Column(sa.String(255))
+    host = sa.Column(sa.String(255))
+    compute_host = sa.Column(sa.String(255))
 
 
 # TODO(stephenfin): Remove in V or later
@@ -1017,14 +1024,14 @@ class Console(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents a console session for an instance."""
     __tablename__ = 'consoles'
     __table_args__ = (
-        Index('consoles_instance_uuid_idx', 'instance_uuid'),
+        sa.Index('consoles_instance_uuid_idx', 'instance_uuid'),
     )
-    id = Column(Integer, primary_key=True)
-    instance_name = Column(String(255))
-    instance_uuid = Column(String(36), ForeignKey('instances.uuid'))
-    password = Column(String(255))
-    port = Column(Integer)
-    pool_id = Column(Integer, ForeignKey('console_pools.id'))
+    id = sa.Column(sa.Integer, primary_key=True)
+    instance_name = sa.Column(sa.String(255))
+    instance_uuid = sa.Column(sa.String(36), sa.ForeignKey('instances.uuid'))
+    password = sa.Column(sa.String(255))
+    port = sa.Column(sa.Integer)
+    pool_id = sa.Column(sa.Integer, sa.ForeignKey('console_pools.id'))
     pool = orm.relationship(ConsolePool, backref=orm.backref('consoles'))
 
 
@@ -1032,12 +1039,12 @@ class InstanceMetadata(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents a user-provided metadata key/value pair for an instance."""
     __tablename__ = 'instance_metadata'
     __table_args__ = (
-        Index('instance_metadata_instance_uuid_idx', 'instance_uuid'),
+        sa.Index('instance_metadata_instance_uuid_idx', 'instance_uuid'),
     )
-    id = Column(Integer, primary_key=True)
-    key = Column(String(255))
-    value = Column(String(255))
-    instance_uuid = Column(String(36), ForeignKey('instances.uuid'))
+    id = sa.Column(sa.Integer, primary_key=True)
+    key = sa.Column(sa.String(255))
+    value = sa.Column(sa.String(255))
+    instance_uuid = sa.Column(sa.String(36), sa.ForeignKey('instances.uuid'))
     instance = orm.relationship(Instance, backref="metadata",
                             foreign_keys=instance_uuid,
                             primaryjoin='and_('
@@ -1050,13 +1057,13 @@ class InstanceSystemMetadata(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents a system-owned metadata key/value pair for an instance."""
     __tablename__ = 'instance_system_metadata'
     __table_args__ = (
-        Index('instance_uuid', 'instance_uuid'),
+        sa.Index('instance_uuid', 'instance_uuid'),
     )
-    id = Column(Integer, primary_key=True)
-    key = Column(String(255), nullable=False)
-    value = Column(String(255))
-    instance_uuid = Column(String(36),
-                           ForeignKey('instances.uuid'),
+    id = sa.Column(sa.Integer, primary_key=True)
+    key = sa.Column(sa.String(255), nullable=False)
+    value = sa.Column(sa.String(255))
+    instance_uuid = sa.Column(sa.String(36),
+                           sa.ForeignKey('instances.uuid'),
                            nullable=False)
 
     instance = orm.relationship(Instance, backref="system_metadata",
@@ -1073,10 +1080,10 @@ class InstanceTypeProjects(BASE, NovaBase, models.SoftDeleteMixin):
         name="uniq_instance_type_projects0instance_type_id0project_id0deleted"
         ),
     )
-    id = Column(Integer, primary_key=True)
-    instance_type_id = Column(Integer, ForeignKey('instance_types.id'),
-                              nullable=False)
-    project_id = Column(String(255))
+    id = sa.Column(sa.Integer, primary_key=True)
+    instance_type_id = sa.Column(
+        sa.Integer, sa.ForeignKey('instance_types.id'), nullable=False)
+    project_id = sa.Column(sa.String(255))
 
     instance_type = orm.relationship(InstanceTypes, backref="projects",
                  foreign_keys=instance_type_id,
@@ -1091,7 +1098,7 @@ class InstanceTypeExtraSpecs(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents additional specs as key/value pairs for an instance_type."""
     __tablename__ = 'instance_type_extra_specs'
     __table_args__ = (
-        Index('instance_type_extra_specs_instance_type_id_key_idx',
+        sa.Index('instance_type_extra_specs_instance_type_id_key_idx',
               'instance_type_id', 'key'),
         schema.UniqueConstraint(
               "instance_type_id", "key", "deleted",
@@ -1100,16 +1107,19 @@ class InstanceTypeExtraSpecs(BASE, NovaBase, models.SoftDeleteMixin):
         ),
         {'mysql_collate': 'utf8_bin'},
     )
-    id = Column(Integer, primary_key=True)
-    key = Column(String(255))
-    value = Column(String(255))
-    instance_type_id = Column(Integer, ForeignKey('instance_types.id'),
-                              nullable=False)
-    instance_type = orm.relationship(InstanceTypes, backref="extra_specs",
-                 foreign_keys=instance_type_id,
-                 primaryjoin='and_('
-                 'InstanceTypeExtraSpecs.instance_type_id == InstanceTypes.id,'
-                 'InstanceTypeExtraSpecs.deleted == 0)')
+    id = sa.Column(sa.Integer, primary_key=True)
+    key = sa.Column(sa.String(255))
+    value = sa.Column(sa.String(255))
+    instance_type_id = sa.Column(
+        sa.Integer, sa.ForeignKey('instance_types.id'), nullable=False)
+    instance_type = orm.relationship(
+        InstanceTypes, backref="extra_specs",
+        foreign_keys=instance_type_id,
+        primaryjoin=(
+            'and_('
+            'InstanceTypeExtraSpecs.instance_type_id == InstanceTypes.id,'
+            'InstanceTypeExtraSpecs.deleted == 0)'),
+    )
 
 
 # TODO(stephenfin): Remove this in the U release or later, once we're sure we
@@ -1124,16 +1134,16 @@ class Cell(BASE, NovaBase, models.SoftDeleteMixin):
         "name", "deleted", name="uniq_cells0name0deleted"
         ),
     )
-    id = Column(Integer, primary_key=True)
+    id = sa.Column(sa.Integer, primary_key=True)
     # Name here is the 'short name' of a cell.  For instance: 'child1'
-    name = Column(String(255))
-    api_url = Column(String(255))
+    name = sa.Column(sa.String(255))
+    api_url = sa.Column(sa.String(255))
 
-    transport_url = Column(String(255), nullable=False)
+    transport_url = sa.Column(sa.String(255), nullable=False)
 
-    weight_offset = Column(Float(), default=0.0)
-    weight_scale = Column(Float(), default=1.0)
-    is_parent = Column(Boolean())
+    weight_offset = sa.Column(sa.Float(), default=0.0)
+    weight_scale = sa.Column(sa.Float(), default=1.0)
+    is_parent = sa.Column(sa.Boolean())
 
 
 # NOTE(alaski): This table exists in the nova_api database and its usage here
@@ -1146,9 +1156,10 @@ class AggregateHost(BASE, NovaBase, models.SoftDeleteMixin):
          name="uniq_aggregate_hosts0host0aggregate_id0deleted"
         ),
     )
-    id = Column(Integer, primary_key=True, autoincrement=True)
-    host = Column(String(255))
-    aggregate_id = Column(Integer, ForeignKey('aggregates.id'), nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, autoincrement=True)
+    host = sa.Column(sa.String(255))
+    aggregate_id = sa.Column(
+        sa.Integer, sa.ForeignKey('aggregates.id'), nullable=False)
 
 
 # NOTE(alaski): This table exists in the nova_api database and its usage here
@@ -1160,13 +1171,14 @@ class AggregateMetadata(BASE, NovaBase, models.SoftDeleteMixin):
         schema.UniqueConstraint("aggregate_id", "key", "deleted",
             name="uniq_aggregate_metadata0aggregate_id0key0deleted"
             ),
-        Index('aggregate_metadata_key_idx', 'key'),
-        Index('aggregate_metadata_value_idx', 'value'),
+        sa.Index('aggregate_metadata_key_idx', 'key'),
+        sa.Index('aggregate_metadata_value_idx', 'value'),
     )
-    id = Column(Integer, primary_key=True)
-    key = Column(String(255), nullable=False)
-    value = Column(String(255), nullable=False)
-    aggregate_id = Column(Integer, ForeignKey('aggregates.id'), nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True)
+    key = sa.Column(sa.String(255), nullable=False)
+    value = sa.Column(sa.String(255), nullable=False)
+    aggregate_id = sa.Column(
+        sa.Integer, sa.ForeignKey('aggregates.id'), nullable=False)
 
 
 # NOTE(alaski): This table exists in the nova_api database and its usage here
@@ -1174,10 +1186,10 @@ class AggregateMetadata(BASE, NovaBase, models.SoftDeleteMixin):
 class Aggregate(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents a cluster of hosts that exists in this zone."""
     __tablename__ = 'aggregates'
-    __table_args__ = (Index('aggregate_uuid_idx', 'uuid'),)
-    id = Column(Integer, primary_key=True, autoincrement=True)
-    uuid = Column(String(36))
-    name = Column(String(255))
+    __table_args__ = (sa.Index('aggregate_uuid_idx', 'uuid'),)
+    id = sa.Column(sa.Integer, primary_key=True, autoincrement=True)
+    uuid = sa.Column(sa.String(36))
+    name = sa.Column(sa.String(255))
     _hosts = orm.relationship(AggregateHost,
                           primaryjoin='and_('
                           'Aggregate.id == AggregateHost.aggregate_id,'
@@ -1215,18 +1227,18 @@ class AgentBuild(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents an agent build."""
     __tablename__ = 'agent_builds'
     __table_args__ = (
-        Index('agent_builds_hypervisor_os_arch_idx', 'hypervisor', 'os',
+        sa.Index('agent_builds_hypervisor_os_arch_idx', 'hypervisor', 'os',
               'architecture'),
         schema.UniqueConstraint("hypervisor", "os", "architecture", "deleted",
                 name="uniq_agent_builds0hypervisor0os0architecture0deleted"),
     )
-    id = Column(Integer, primary_key=True)
-    hypervisor = Column(String(255))
-    os = Column(String(255))
-    architecture = Column(String(255))
-    version = Column(String(255))
-    url = Column(String(255))
-    md5hash = Column(String(255))
+    id = sa.Column(sa.Integer, primary_key=True)
+    hypervisor = sa.Column(sa.String(255))
+    os = sa.Column(sa.String(255))
+    architecture = sa.Column(sa.String(255))
+    version = sa.Column(sa.String(255))
+    url = sa.Column(sa.String(255))
+    md5hash = sa.Column(sa.String(255))
 
 
 # TODO(stephenfin): Remove this in the W release or later, once we're sure we
@@ -1235,81 +1247,84 @@ class BandwidthUsage(BASE, NovaBase, models.SoftDeleteMixin):
     """Cache for instance bandwidth usage data pulled from the hypervisor."""
     __tablename__ = 'bw_usage_cache'
     __table_args__ = (
-        Index('bw_usage_cache_uuid_start_period_idx', 'uuid',
+        sa.Index('bw_usage_cache_uuid_start_period_idx', 'uuid',
               'start_period'),
     )
-    id = Column(Integer, primary_key=True, nullable=False)
-    uuid = Column(String(36))
-    mac = Column(String(255))
-    start_period = Column(DateTime, nullable=False)
-    last_refreshed = Column(DateTime)
-    bw_in = Column(BigInteger)
-    bw_out = Column(BigInteger)
-    last_ctr_in = Column(BigInteger)
-    last_ctr_out = Column(BigInteger)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    uuid = sa.Column(sa.String(36))
+    mac = sa.Column(sa.String(255))
+    start_period = sa.Column(sa.DateTime, nullable=False)
+    last_refreshed = sa.Column(sa.DateTime)
+    bw_in = sa.Column(sa.BigInteger)
+    bw_out = sa.Column(sa.BigInteger)
+    last_ctr_in = sa.Column(sa.BigInteger)
+    last_ctr_out = sa.Column(sa.BigInteger)
 
 
 class VolumeUsage(BASE, NovaBase, models.SoftDeleteMixin):
     """Cache for volume usage data pulled from the hypervisor."""
     __tablename__ = 'volume_usage_cache'
     __table_args__ = ()
-    id = Column(Integer, primary_key=True, nullable=False)
-    volume_id = Column(String(36), nullable=False)
-    instance_uuid = Column(String(36))
-    project_id = Column(String(36))
-    user_id = Column(String(64))
-    availability_zone = Column(String(255))
-    tot_last_refreshed = Column(DateTime)
-    tot_reads = Column(BigInteger, default=0)
-    tot_read_bytes = Column(BigInteger, default=0)
-    tot_writes = Column(BigInteger, default=0)
-    tot_write_bytes = Column(BigInteger, default=0)
-    curr_last_refreshed = Column(DateTime)
-    curr_reads = Column(BigInteger, default=0)
-    curr_read_bytes = Column(BigInteger, default=0)
-    curr_writes = Column(BigInteger, default=0)
-    curr_write_bytes = Column(BigInteger, default=0)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    volume_id = sa.Column(sa.String(36), nullable=False)
+    instance_uuid = sa.Column(sa.String(36))
+    project_id = sa.Column(sa.String(36))
+    user_id = sa.Column(sa.String(64))
+    availability_zone = sa.Column(sa.String(255))
+    tot_last_refreshed = sa.Column(sa.DateTime)
+    tot_reads = sa.Column(sa.BigInteger, default=0)
+    tot_read_bytes = sa.Column(sa.BigInteger, default=0)
+    tot_writes = sa.Column(sa.BigInteger, default=0)
+    tot_write_bytes = sa.Column(sa.BigInteger, default=0)
+    curr_last_refreshed = sa.Column(sa.DateTime)
+    curr_reads = sa.Column(sa.BigInteger, default=0)
+    curr_read_bytes = sa.Column(sa.BigInteger, default=0)
+    curr_writes = sa.Column(sa.BigInteger, default=0)
+    curr_write_bytes = sa.Column(sa.BigInteger, default=0)
 
 
 class S3Image(BASE, NovaBase, models.SoftDeleteMixin):
     """Compatibility layer for the S3 image service talking to Glance."""
     __tablename__ = 's3_images'
     __table_args__ = ()
-    id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
-    uuid = Column(String(36), nullable=False)
+    id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False, autoincrement=True)
+    uuid = sa.Column(sa.String(36), nullable=False)
 
 
 class VolumeIdMapping(BASE, NovaBase, models.SoftDeleteMixin):
     """Compatibility layer for the EC2 volume service."""
     __tablename__ = 'volume_id_mappings'
     __table_args__ = ()
-    id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
-    uuid = Column(String(36), nullable=False)
+    id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False, autoincrement=True)
+    uuid = sa.Column(sa.String(36), nullable=False)
 
 
 class SnapshotIdMapping(BASE, NovaBase, models.SoftDeleteMixin):
     """Compatibility layer for the EC2 snapshot service."""
     __tablename__ = 'snapshot_id_mappings'
     __table_args__ = ()
-    id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
-    uuid = Column(String(36), nullable=False)
+    id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False, autoincrement=True)
+    uuid = sa.Column(sa.String(36), nullable=False)
 
 
 class InstanceFault(BASE, NovaBase, models.SoftDeleteMixin):
     __tablename__ = 'instance_faults'
     __table_args__ = (
-        Index('instance_faults_host_idx', 'host'),
-        Index('instance_faults_instance_uuid_deleted_created_at_idx',
+        sa.Index('instance_faults_host_idx', 'host'),
+        sa.Index('instance_faults_instance_uuid_deleted_created_at_idx',
               'instance_uuid', 'deleted', 'created_at')
     )
 
-    id = Column(Integer, primary_key=True, nullable=False)
-    instance_uuid = Column(String(36),
-                           ForeignKey('instances.uuid'))
-    code = Column(Integer(), nullable=False)
-    message = Column(String(255))
-    details = Column(MediumText())
-    host = Column(String(255))
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    instance_uuid = sa.Column(sa.String(36),
+                           sa.ForeignKey('instances.uuid'))
+    code = sa.Column(sa.Integer(), nullable=False)
+    message = sa.Column(sa.String(255))
+    details = sa.Column(MediumText())
+    host = sa.Column(sa.String(255))
 
 
 class InstanceAction(BASE, NovaBase, models.SoftDeleteMixin):
@@ -1320,22 +1335,23 @@ class InstanceAction(BASE, NovaBase, models.SoftDeleteMixin):
     """
     __tablename__ = 'instance_actions'
     __table_args__ = (
-        Index('instance_uuid_idx', 'instance_uuid'),
-        Index('request_id_idx', 'request_id'),
-        Index('instance_actions_instance_uuid_updated_at_idx',
+        sa.Index('instance_uuid_idx', 'instance_uuid'),
+        sa.Index('request_id_idx', 'request_id'),
+        sa.Index('instance_actions_instance_uuid_updated_at_idx',
               'instance_uuid', 'updated_at')
     )
 
-    id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
-    action = Column(String(255))
-    instance_uuid = Column(String(36),
-                           ForeignKey('instances.uuid'))
-    request_id = Column(String(255))
-    user_id = Column(String(255))
-    project_id = Column(String(255))
-    start_time = Column(DateTime, default=timeutils.utcnow)
-    finish_time = Column(DateTime)
-    message = Column(String(255))
+    id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False, autoincrement=True)
+    action = sa.Column(sa.String(255))
+    instance_uuid = sa.Column(sa.String(36),
+                           sa.ForeignKey('instances.uuid'))
+    request_id = sa.Column(sa.String(255))
+    user_id = sa.Column(sa.String(255))
+    project_id = sa.Column(sa.String(255))
+    start_time = sa.Column(sa.DateTime, default=timeutils.utcnow)
+    finish_time = sa.Column(sa.DateTime)
+    message = sa.Column(sa.String(255))
 
 
 class InstanceActionEvent(BASE, NovaBase, models.SoftDeleteMixin):
@@ -1343,25 +1359,27 @@ class InstanceActionEvent(BASE, NovaBase, models.SoftDeleteMixin):
     __tablename__ = 'instance_actions_events'
     __table_args__ = ()
 
-    id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
-    event = Column(String(255))
-    action_id = Column(Integer, ForeignKey('instance_actions.id'))
-    start_time = Column(DateTime, default=timeutils.utcnow)
-    finish_time = Column(DateTime)
-    result = Column(String(255))
-    traceback = Column(Text)
-    host = Column(String(255))
-    details = Column(Text)
+    id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False, autoincrement=True)
+    event = sa.Column(sa.String(255))
+    action_id = sa.Column(sa.Integer, sa.ForeignKey('instance_actions.id'))
+    start_time = sa.Column(sa.DateTime, default=timeutils.utcnow)
+    finish_time = sa.Column(sa.DateTime)
+    result = sa.Column(sa.String(255))
+    traceback = sa.Column(sa.Text)
+    host = sa.Column(sa.String(255))
+    details = sa.Column(sa.Text)
 
 
 class InstanceIdMapping(BASE, NovaBase, models.SoftDeleteMixin):
     """Compatibility layer for the EC2 instance service."""
     __tablename__ = 'instance_id_mappings'
     __table_args__ = (
-        Index('ix_instance_id_mappings_uuid', 'uuid'),
+        sa.Index('ix_instance_id_mappings_uuid', 'uuid'),
     )
-    id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
-    uuid = Column(String(36), nullable=False)
+    id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False, autoincrement=True)
+    uuid = sa.Column(sa.String(36), nullable=False)
 
 
 class TaskLog(BASE, NovaBase, models.SoftDeleteMixin):
@@ -1372,21 +1390,22 @@ class TaskLog(BASE, NovaBase, models.SoftDeleteMixin):
             'task_name', 'host', 'period_beginning', 'period_ending',
             name="uniq_task_log0task_name0host0period_beginning0period_ending"
         ),
-        Index('ix_task_log_period_beginning', 'period_beginning'),
-        Index('ix_task_log_host', 'host'),
-        Index('ix_task_log_period_ending', 'period_ending'),
+        sa.Index('ix_task_log_period_beginning', 'period_beginning'),
+        sa.Index('ix_task_log_host', 'host'),
+        sa.Index('ix_task_log_period_ending', 'period_ending'),
     )
-    id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
-    task_name = Column(String(255), nullable=False)
-    state = Column(String(255), nullable=False)
-    host = Column(String(255), nullable=False)
-    period_beginning = Column(DateTime, default=timeutils.utcnow,
+    id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False, autoincrement=True)
+    task_name = sa.Column(sa.String(255), nullable=False)
+    state = sa.Column(sa.String(255), nullable=False)
+    host = sa.Column(sa.String(255), nullable=False)
+    period_beginning = sa.Column(sa.DateTime, default=timeutils.utcnow,
                               nullable=False)
-    period_ending = Column(DateTime, default=timeutils.utcnow,
+    period_ending = sa.Column(sa.DateTime, default=timeutils.utcnow,
                            nullable=False)
-    message = Column(String(255), nullable=False)
-    task_items = Column(Integer(), default=0)
-    errors = Column(Integer(), default=0)
+    message = sa.Column(sa.String(255), nullable=False)
+    task_items = sa.Column(sa.Integer(), default=0)
+    errors = sa.Column(sa.Integer(), default=0)
 
 
 # NOTE(alaski): This table exists in the nova_api database and its usage here
@@ -1395,11 +1414,11 @@ class InstanceGroupMember(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents the members for an instance group."""
     __tablename__ = 'instance_group_member'
     __table_args__ = (
-        Index('instance_group_member_instance_idx', 'instance_id'),
+        sa.Index('instance_group_member_instance_idx', 'instance_id'),
     )
-    id = Column(Integer, primary_key=True, nullable=False)
-    instance_id = Column(String(255))
-    group_id = Column(Integer, ForeignKey('instance_groups.id'),
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    instance_id = sa.Column(sa.String(255))
+    group_id = sa.Column(sa.Integer, sa.ForeignKey('instance_groups.id'),
                       nullable=False)
 
 
@@ -1409,11 +1428,11 @@ class InstanceGroupPolicy(BASE, NovaBase, models.SoftDeleteMixin):
     """Represents the policy type for an instance group."""
     __tablename__ = 'instance_group_policy'
     __table_args__ = (
-        Index('instance_group_policy_policy_idx', 'policy'),
+        sa.Index('instance_group_policy_policy_idx', 'policy'),
     )
-    id = Column(Integer, primary_key=True, nullable=False)
-    policy = Column(String(255))
-    group_id = Column(Integer, ForeignKey('instance_groups.id'),
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    policy = sa.Column(sa.String(255))
+    group_id = sa.Column(sa.Integer, sa.ForeignKey('instance_groups.id'),
                       nullable=False)
 
 
@@ -1432,11 +1451,11 @@ class InstanceGroup(BASE, NovaBase, models.SoftDeleteMixin):
                                  name="uniq_instance_groups0uuid0deleted"),
     )
 
-    id = Column(Integer, primary_key=True, autoincrement=True)
-    user_id = Column(String(255))
-    project_id = Column(String(255))
-    uuid = Column(String(36), nullable=False)
-    name = Column(String(255))
+    id = sa.Column(sa.Integer, primary_key=True, autoincrement=True)
+    user_id = sa.Column(sa.String(255))
+    project_id = sa.Column(sa.String(255))
+    uuid = sa.Column(sa.String(36), nullable=False)
+    name = sa.Column(sa.String(255))
     _policies = orm.relationship(InstanceGroupPolicy, primaryjoin='and_('
         'InstanceGroup.id == InstanceGroupPolicy.group_id,'
         'InstanceGroupPolicy.deleted == 0,'
@@ -1460,45 +1479,45 @@ class PciDevice(BASE, NovaBase, models.SoftDeleteMixin):
     """
     __tablename__ = 'pci_devices'
     __table_args__ = (
-        Index('ix_pci_devices_compute_node_id_deleted',
+        sa.Index('ix_pci_devices_compute_node_id_deleted',
               'compute_node_id', 'deleted'),
-        Index('ix_pci_devices_instance_uuid_deleted',
+        sa.Index('ix_pci_devices_instance_uuid_deleted',
               'instance_uuid', 'deleted'),
-        Index('ix_pci_devices_compute_node_id_parent_addr_deleted',
+        sa.Index('ix_pci_devices_compute_node_id_parent_addr_deleted',
               'compute_node_id', 'parent_addr', 'deleted'),
         schema.UniqueConstraint(
             "compute_node_id", "address", "deleted",
             name="uniq_pci_devices0compute_node_id0address0deleted")
     )
-    id = Column(Integer, primary_key=True)
-    uuid = Column(String(36))
-    compute_node_id = Column(Integer, ForeignKey('compute_nodes.id'),
+    id = sa.Column(sa.Integer, primary_key=True)
+    uuid = sa.Column(sa.String(36))
+    compute_node_id = sa.Column(sa.Integer, sa.ForeignKey('compute_nodes.id'),
                              nullable=False)
 
     # physical address of device domain:bus:slot.func (0000:09:01.1)
-    address = Column(String(12), nullable=False)
+    address = sa.Column(sa.String(12), nullable=False)
 
-    vendor_id = Column(String(4), nullable=False)
-    product_id = Column(String(4), nullable=False)
-    dev_type = Column(String(8), nullable=False)
-    dev_id = Column(String(255))
+    vendor_id = sa.Column(sa.String(4), nullable=False)
+    product_id = sa.Column(sa.String(4), nullable=False)
+    dev_type = sa.Column(sa.String(8), nullable=False)
+    dev_id = sa.Column(sa.String(255))
 
     # label is abstract device name, that is used to unify devices with the
     # same functionality with different addresses or host.
-    label = Column(String(255), nullable=False)
+    label = sa.Column(sa.String(255), nullable=False)
 
-    status = Column(String(36), nullable=False)
+    status = sa.Column(sa.String(36), nullable=False)
     # the request_id is used to identify a device that is allocated for a
     # particular request
-    request_id = Column(String(36), nullable=True)
+    request_id = sa.Column(sa.String(36), nullable=True)
 
-    extra_info = Column(Text)
+    extra_info = sa.Column(sa.Text)
 
-    instance_uuid = Column(String(36))
+    instance_uuid = sa.Column(sa.String(36))
 
-    numa_node = Column(Integer, nullable=True)
+    numa_node = sa.Column(sa.Integer, nullable=True)
 
-    parent_addr = Column(String(12), nullable=True)
+    parent_addr = sa.Column(sa.String(12), nullable=True)
     instance = orm.relationship(Instance, backref="pci_devices",
                                 foreign_keys=instance_uuid,
                                 primaryjoin='and_('
@@ -1511,10 +1530,10 @@ class Tag(BASE, models.ModelBase):
 
     __tablename__ = "tags"
     __table_args__ = (
-        Index('tags_tag_idx', 'tag'),
+        sa.Index('tags_tag_idx', 'tag'),
     )
-    resource_id = Column(String(36), primary_key=True, nullable=False)
-    tag = Column(Unicode(80), primary_key=True, nullable=False)
+    resource_id = sa.Column(sa.String(36), primary_key=True, nullable=False)
+    tag = sa.Column(sa.Unicode(80), primary_key=True, nullable=False)
 
     instance = orm.relationship(
         "Instance",
@@ -1532,19 +1551,19 @@ class ResourceProvider(BASE, models.ModelBase):
 
     __tablename__ = "resource_providers"
     __table_args__ = (
-        Index('resource_providers_uuid_idx', 'uuid'),
+        sa.Index('resource_providers_uuid_idx', 'uuid'),
         schema.UniqueConstraint('uuid',
             name='uniq_resource_providers0uuid'),
-        Index('resource_providers_name_idx', 'name'),
+        sa.Index('resource_providers_name_idx', 'name'),
         schema.UniqueConstraint('name',
             name='uniq_resource_providers0name')
     )
 
-    id = Column(Integer, primary_key=True, nullable=False)
-    uuid = Column(String(36), nullable=False)
-    name = Column(Unicode(200), nullable=True)
-    generation = Column(Integer, default=0)
-    can_host = Column(Integer, default=0)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    uuid = sa.Column(sa.String(36), nullable=False)
+    name = sa.Column(sa.Unicode(200), nullable=True)
+    generation = sa.Column(sa.Integer, default=0)
+    can_host = sa.Column(sa.Integer, default=0)
 
 
 # NOTE(alaski): This table exists in the nova_api database and its usage here
@@ -1554,25 +1573,25 @@ class Inventory(BASE, models.ModelBase):
 
     __tablename__ = "inventories"
     __table_args__ = (
-        Index('inventories_resource_provider_id_idx',
+        sa.Index('inventories_resource_provider_id_idx',
               'resource_provider_id'),
-        Index('inventories_resource_class_id_idx',
+        sa.Index('inventories_resource_class_id_idx',
               'resource_class_id'),
-        Index('inventories_resource_provider_resource_class_idx',
+        sa.Index('inventories_resource_provider_resource_class_idx',
               'resource_provider_id', 'resource_class_id'),
         schema.UniqueConstraint('resource_provider_id', 'resource_class_id',
             name='uniq_inventories0resource_provider_resource_class')
     )
 
-    id = Column(Integer, primary_key=True, nullable=False)
-    resource_provider_id = Column(Integer, nullable=False)
-    resource_class_id = Column(Integer, nullable=False)
-    total = Column(Integer, nullable=False)
-    reserved = Column(Integer, nullable=False)
-    min_unit = Column(Integer, nullable=False)
-    max_unit = Column(Integer, nullable=False)
-    step_size = Column(Integer, nullable=False)
-    allocation_ratio = Column(Float, nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    resource_provider_id = sa.Column(sa.Integer, nullable=False)
+    resource_class_id = sa.Column(sa.Integer, nullable=False)
+    total = sa.Column(sa.Integer, nullable=False)
+    reserved = sa.Column(sa.Integer, nullable=False)
+    min_unit = sa.Column(sa.Integer, nullable=False)
+    max_unit = sa.Column(sa.Integer, nullable=False)
+    step_size = sa.Column(sa.Integer, nullable=False)
+    allocation_ratio = sa.Column(sa.Float, nullable=False)
     resource_provider = orm.relationship(
         "ResourceProvider",
         primaryjoin=('and_(Inventory.resource_provider_id == '
@@ -1587,19 +1606,19 @@ class Allocation(BASE, models.ModelBase):
 
     __tablename__ = "allocations"
     __table_args__ = (
-        Index('allocations_resource_provider_class_used_idx',
+        sa.Index('allocations_resource_provider_class_used_idx',
               'resource_provider_id', 'resource_class_id',
               'used'),
-        Index('allocations_resource_class_id_idx',
+        sa.Index('allocations_resource_class_id_idx',
               'resource_class_id'),
-        Index('allocations_consumer_id_idx', 'consumer_id')
+        sa.Index('allocations_consumer_id_idx', 'consumer_id')
     )
 
-    id = Column(Integer, primary_key=True, nullable=False)
-    resource_provider_id = Column(Integer, nullable=False)
-    consumer_id = Column(String(36), nullable=False)
-    resource_class_id = Column(Integer, nullable=False)
-    used = Column(Integer, nullable=False)
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    resource_provider_id = sa.Column(sa.Integer, nullable=False)
+    consumer_id = sa.Column(sa.String(36), nullable=False)
+    resource_class_id = sa.Column(sa.Integer, nullable=False)
+    used = sa.Column(sa.Integer, nullable=False)
 
 
 # NOTE(alaski): This table exists in the nova_api database and its usage here
@@ -1609,12 +1628,13 @@ class ResourceProviderAggregate(BASE, models.ModelBase):
 
     __tablename__ = 'resource_provider_aggregates'
     __table_args__ = (
-        Index('resource_provider_aggregates_aggregate_id_idx',
+        sa.Index('resource_provider_aggregates_aggregate_id_idx',
               'aggregate_id'),
     )
 
-    resource_provider_id = Column(Integer, primary_key=True, nullable=False)
-    aggregate_id = Column(Integer, primary_key=True, nullable=False)
+    resource_provider_id = sa.Column(
+        sa.Integer, primary_key=True, nullable=False)
+    aggregate_id = sa.Column(sa.Integer, primary_key=True, nullable=False)
 
 
 class ConsoleAuthToken(BASE, NovaBase):
@@ -1622,23 +1642,25 @@ class ConsoleAuthToken(BASE, NovaBase):
 
     __tablename__ = 'console_auth_tokens'
     __table_args__ = (
-        Index('console_auth_tokens_instance_uuid_idx', 'instance_uuid'),
-        Index('console_auth_tokens_host_expires_idx', 'host', 'expires'),
-        Index('console_auth_tokens_token_hash_idx', 'token_hash'),
-        Index('console_auth_tokens_token_hash_instance_uuid_idx', 'token_hash',
-              'instance_uuid'),
+        sa.Index('console_auth_tokens_instance_uuid_idx', 'instance_uuid'),
+        sa.Index('console_auth_tokens_host_expires_idx', 'host', 'expires'),
+        sa.Index('console_auth_tokens_token_hash_idx', 'token_hash'),
+        sa.Index(
+            'console_auth_tokens_token_hash_instance_uuid_idx', 'token_hash',
+            'instance_uuid',
+        ),
         schema.UniqueConstraint("token_hash",
                                 name="uniq_console_auth_tokens0token_hash")
     )
-    id = Column(Integer, primary_key=True, nullable=False)
-    token_hash = Column(String(255), nullable=False)
-    console_type = Column(String(255), nullable=False)
-    host = Column(String(255), nullable=False)
-    port = Column(Integer, nullable=False)
-    internal_access_path = Column(String(255))
-    instance_uuid = Column(String(36), nullable=False)
-    expires = Column(Integer, nullable=False)
-    access_url_base = Column(String(255))
+    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
+    token_hash = sa.Column(sa.String(255), nullable=False)
+    console_type = sa.Column(sa.String(255), nullable=False)
+    host = sa.Column(sa.String(255), nullable=False)
+    port = sa.Column(sa.Integer, nullable=False)
+    internal_access_path = sa.Column(sa.String(255))
+    instance_uuid = sa.Column(sa.String(36), nullable=False)
+    expires = sa.Column(sa.Integer, nullable=False)
+    access_url_base = sa.Column(sa.String(255))
 
     instance = orm.relationship(
         "Instance",
diff --git a/nova/objects/aggregate.py b/nova/objects/aggregate.py
index 548fc038e598..368c102f5df5 100644
--- a/nova/objects/aggregate.py
+++ b/nova/objects/aggregate.py
@@ -16,8 +16,7 @@ from oslo_db import exception as db_exc
 from oslo_log import log as logging
 from oslo_utils import excutils
 from oslo_utils import uuidutils
-from sqlalchemy.orm import contains_eager
-from sqlalchemy.orm import joinedload
+from sqlalchemy import orm
 
 from nova.compute import utils as compute_utils
 from nova.db.sqlalchemy import api as db_api
@@ -36,8 +35,8 @@ DEPRECATED_FIELDS = ['deleted', 'deleted_at']
 @db_api.api_context_manager.reader
 def _aggregate_get_from_db(context, aggregate_id):
     query = context.session.query(api_models.Aggregate).\
-            options(joinedload('_hosts')).\
-            options(joinedload('_metadata'))
+            options(orm.joinedload('_hosts')).\
+            options(orm.joinedload('_metadata'))
     query = query.filter(api_models.Aggregate.id == aggregate_id)
 
     aggregate = query.first()
@@ -51,8 +50,8 @@ def _aggregate_get_from_db(context, aggregate_id):
 @db_api.api_context_manager.reader
 def _aggregate_get_from_db_by_uuid(context, aggregate_uuid):
     query = context.session.query(api_models.Aggregate).\
-            options(joinedload('_hosts')).\
-            options(joinedload('_metadata'))
+            options(orm.joinedload('_hosts')).\
+            options(orm.joinedload('_metadata'))
     query = query.filter(api_models.Aggregate.uuid == aggregate_uuid)
 
     aggregate = query.first()
@@ -415,8 +414,8 @@ class Aggregate(base.NovaPersistentObject, base.NovaObject):
 @db_api.api_context_manager.reader
 def _get_all_from_db(context):
     query = context.session.query(api_models.Aggregate).\
-            options(joinedload('_hosts')).\
-            options(joinedload('_metadata'))
+            options(orm.joinedload('_hosts')).\
+            options(orm.joinedload('_metadata'))
 
     return query.all()
 
@@ -424,8 +423,8 @@ def _get_all_from_db(context):
 @db_api.api_context_manager.reader
 def _get_by_host_from_db(context, host, key=None):
     query = context.session.query(api_models.Aggregate).\
-            options(joinedload('_hosts')).\
-            options(joinedload('_metadata'))
+            options(orm.joinedload('_hosts')).\
+            options(orm.joinedload('_metadata'))
     query = query.join('_hosts')
     query = query.filter(api_models.AggregateHost.host == host)
 
@@ -445,8 +444,8 @@ def _get_by_metadata_from_db(context, key=None, value=None):
         query = query.filter(api_models.AggregateMetadata.key == key)
     if value is not None:
         query = query.filter(api_models.AggregateMetadata.value == value)
-    query = query.options(contains_eager("_metadata"))
-    query = query.options(joinedload("_hosts"))
+    query = query.options(orm.contains_eager("_metadata"))
+    query = query.options(orm.joinedload("_hosts"))
 
     return query.all()
 
@@ -477,8 +476,8 @@ def _get_non_matching_by_metadata_keys_from_db(context, ignored_keys,
         query = query.filter(~api_models.AggregateMetadata.key.in_(
             ignored_keys))
 
-    query = query.options(contains_eager("_metadata"))
-    query = query.options(joinedload("_hosts"))
+    query = query.options(orm.contains_eager("_metadata"))
+    query = query.options(orm.joinedload("_hosts"))
 
     return query.all()
 
diff --git a/nova/objects/cell_mapping.py b/nova/objects/cell_mapping.py
index 63e3648d5fbf..7633ad0e7591 100644
--- a/nova/objects/cell_mapping.py
+++ b/nova/objects/cell_mapping.py
@@ -14,9 +14,8 @@ from urllib import parse as urlparse
 
 from oslo_log import log as logging
 from oslo_utils import versionutils
-from sqlalchemy.sql.expression import asc
-from sqlalchemy.sql import false
-from sqlalchemy.sql import true
+from sqlalchemy import sql
+from sqlalchemy.sql import expression
 
 import nova.conf
 from nova.db.sqlalchemy import api as db_api
@@ -250,7 +249,7 @@ class CellMappingList(base.ObjectListBase, base.NovaObject):
     @db_api.api_context_manager.reader
     def _get_all_from_db(context):
         return context.session.query(api_models.CellMapping).order_by(
-            asc(api_models.CellMapping.id)).all()
+            expression.asc(api_models.CellMapping.id)).all()
 
     @base.remotable_classmethod
     def get_all(cls, context):
@@ -261,12 +260,13 @@ class CellMappingList(base.ObjectListBase, base.NovaObject):
     @db_api.api_context_manager.reader
     def _get_by_disabled_from_db(context, disabled):
         if disabled:
-            return context.session.query(api_models.CellMapping).filter_by(
-                disabled=true()).order_by(asc(api_models.CellMapping.id)).all()
+            return context.session.query(api_models.CellMapping)\
+                .filter_by(disabled=sql.true())\
+                .order_by(expression.asc(api_models.CellMapping.id)).all()
         else:
-            return context.session.query(api_models.CellMapping).filter_by(
-                disabled=false()).order_by(asc(
-                    api_models.CellMapping.id)).all()
+            return context.session.query(api_models.CellMapping)\
+                .filter_by(disabled=sql.false())\
+                .order_by(expression.asc(api_models.CellMapping.id)).all()
 
     @base.remotable_classmethod
     def get_by_disabled(cls, context, disabled):
diff --git a/nova/objects/compute_node.py b/nova/objects/compute_node.py
index cf5d3ca8d881..6de7822cdecb 100644
--- a/nova/objects/compute_node.py
+++ b/nova/objects/compute_node.py
@@ -12,12 +12,11 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-
 from oslo_serialization import jsonutils
 from oslo_utils import uuidutils
 from oslo_utils import versionutils
-from sqlalchemy import or_
-from sqlalchemy.sql import null
+import sqlalchemy as sa
+from sqlalchemy import sql
 
 import nova.conf
 from nova.db import api as db
@@ -500,13 +499,13 @@ def _get_node_empty_ratio(context, max_count):
 
     Results are limited by ``max_count``.
     """
-    return context.session.query(models.ComputeNode).filter(or_(
+    return context.session.query(models.ComputeNode).filter(sa.or_(
         models.ComputeNode.ram_allocation_ratio == '0.0',
         models.ComputeNode.cpu_allocation_ratio == '0.0',
         models.ComputeNode.disk_allocation_ratio == '0.0',
-        models.ComputeNode.ram_allocation_ratio == null(),
-        models.ComputeNode.cpu_allocation_ratio == null(),
-        models.ComputeNode.disk_allocation_ratio == null()
+        models.ComputeNode.ram_allocation_ratio == sql.null(),
+        models.ComputeNode.cpu_allocation_ratio == sql.null(),
+        models.ComputeNode.disk_allocation_ratio == sql.null()
     )).filter(models.ComputeNode.deleted == 0).limit(max_count).all()
 
 
diff --git a/nova/objects/flavor.py b/nova/objects/flavor.py
index c590fc143225..546b525dadb9 100644
--- a/nova/objects/flavor.py
+++ b/nova/objects/flavor.py
@@ -15,10 +15,10 @@
 from oslo_db import exception as db_exc
 from oslo_db.sqlalchemy import utils as sqlalchemyutils
 from oslo_utils import versionutils
-from sqlalchemy import or_
-from sqlalchemy.orm import joinedload
-from sqlalchemy.sql.expression import asc
-from sqlalchemy.sql import true
+import sqlalchemy as sa
+from sqlalchemy import orm
+from sqlalchemy import sql
+from sqlalchemy.sql import expression
 
 import nova.conf
 from nova.db.sqlalchemy import api as db_api
@@ -55,9 +55,9 @@ def _dict_with_extra_specs(flavor_model):
 @db_api.api_context_manager.reader
 def _get_projects_from_db(context, flavorid):
     db_flavor = context.session.query(api_models.Flavors).\
-                filter_by(flavorid=flavorid).\
-                options(joinedload('projects')).\
-                first()
+        filter_by(flavorid=flavorid).\
+        options(orm.joinedload('projects')).\
+        first()
     if not db_flavor:
         raise exception.FlavorNotFound(flavor_id=flavorid)
     return [x['project_id'] for x in db_flavor['projects']]
@@ -272,13 +272,13 @@ class Flavor(base.NovaPersistentObject, base.NovaObject,
     @db_api.api_context_manager.reader
     def _flavor_get_query_from_db(context):
         query = context.session.query(api_models.Flavors).\
-                options(joinedload('extra_specs'))
+            options(orm.joinedload('extra_specs'))
         if not context.is_admin:
-            the_filter = [api_models.Flavors.is_public == true()]
+            the_filter = [api_models.Flavors.is_public == sql.true()]
             the_filter.extend([
                 api_models.Flavors.projects.any(project_id=context.project_id)
             ])
-            query = query.filter(or_(*the_filter))
+            query = query.filter(sa.or_(*the_filter))
         return query
 
     @staticmethod
@@ -309,7 +309,7 @@ class Flavor(base.NovaPersistentObject, base.NovaObject,
         """Returns a dict describing specific flavor_id."""
         result = Flavor._flavor_get_query_from_db(context).\
                         filter_by(flavorid=flavor_id).\
-                        order_by(asc(api_models.Flavors.id)).\
+                        order_by(expression.asc(api_models.Flavors.id)).\
                         first()
         if not result:
             raise exception.FlavorNotFound(flavor_id=flavor_id)
@@ -609,7 +609,7 @@ def _flavor_get_all_from_db(context, inactive, filters, sort_key, sort_dir,
             the_filter.extend([api_models.Flavors.projects.any(
                 project_id=context.project_id)])
         if len(the_filter) > 1:
-            query = query.filter(or_(*the_filter))
+            query = query.filter(sa.or_(*the_filter))
         else:
             query = query.filter(the_filter[0])
     marker_row = None
diff --git a/nova/objects/host_mapping.py b/nova/objects/host_mapping.py
index bde342302b5b..52f39be70bf6 100644
--- a/nova/objects/host_mapping.py
+++ b/nova/objects/host_mapping.py
@@ -11,7 +11,7 @@
 #    under the License.
 
 from oslo_db import exception as db_exc
-from sqlalchemy.orm import joinedload
+from sqlalchemy import orm
 
 from nova import context
 from nova.db.sqlalchemy import api as db_api
@@ -89,9 +89,9 @@ class HostMapping(base.NovaTimestampObject, base.NovaObject):
     @staticmethod
     @db_api.api_context_manager.reader
     def _get_by_host_from_db(context, host):
-        db_mapping = (context.session.query(api_models.HostMapping)
-                      .options(joinedload('cell_mapping'))
-                      .filter(api_models.HostMapping.host == host)).first()
+        db_mapping = context.session.query(api_models.HostMapping)\
+            .options(orm.joinedload('cell_mapping'))\
+            .filter(api_models.HostMapping.host == host).first()
         if not db_mapping:
             raise exception.HostMappingNotFound(name=host)
         return db_mapping
@@ -160,7 +160,7 @@ class HostMappingList(base.ObjectListBase, base.NovaObject):
     @db_api.api_context_manager.reader
     def _get_from_db(context, cell_id=None):
         query = (context.session.query(api_models.HostMapping)
-                 .options(joinedload('cell_mapping')))
+                 .options(orm.joinedload('cell_mapping')))
         if cell_id:
             query = query.filter(api_models.HostMapping.cell_id == cell_id)
         return query.all()
diff --git a/nova/objects/instance.py b/nova/objects/instance.py
index d50efc515934..0c43f0f2753c 100644
--- a/nova/objects/instance.py
+++ b/nova/objects/instance.py
@@ -20,10 +20,9 @@ from oslo_log import log as logging
 from oslo_serialization import jsonutils
 from oslo_utils import timeutils
 from oslo_utils import versionutils
-from sqlalchemy import or_
-from sqlalchemy.sql import false
+import sqlalchemy as sa
+from sqlalchemy import sql
 from sqlalchemy.sql import func
-from sqlalchemy.sql import null
 
 from nova import availability_zones as avail_zone
 from nova.compute import task_states
@@ -1516,9 +1515,9 @@ class InstanceList(base.ObjectListBase, base.NovaObject):
         # NOTE(melwitt): Copied from nova/db/sqlalchemy/api.py:
         # It would be better to have vm_state not be nullable
         # but until then we test it explicitly as a workaround.
-        not_soft_deleted = or_(
+        not_soft_deleted = sa.or_(
             models.Instance.vm_state != vm_states.SOFT_DELETED,
-            models.Instance.vm_state == null()
+            models.Instance.vm_state == sql.null()
             )
         project_query = context.session.query(
             func.count(models.Instance.id),
@@ -1531,8 +1530,10 @@ class InstanceList(base.ObjectListBase, base.NovaObject):
         # non-hidden version of the instance in another cell database and the
         # API will only show one of them, so we don't count the hidden copy.
         project_query = project_query.filter(
-            or_(models.Instance.hidden == false(),
-                models.Instance.hidden == null()))
+            sa.or_(
+                models.Instance.hidden == sql.false(),
+                models.Instance.hidden == sql.null(),
+            ))
 
         project_result = project_query.first()
         fields = ('instances', 'cores', 'ram')
diff --git a/nova/objects/instance_group.py b/nova/objects/instance_group.py
index 831e832670cd..9e4f8e0b7e51 100644
--- a/nova/objects/instance_group.py
+++ b/nova/objects/instance_group.py
@@ -19,8 +19,7 @@ from oslo_log import log as logging
 from oslo_serialization import jsonutils
 from oslo_utils import uuidutils
 from oslo_utils import versionutils
-from sqlalchemy.orm import contains_eager
-from sqlalchemy.orm import joinedload
+from sqlalchemy import orm
 
 from nova.compute import utils as compute_utils
 from nova.db.sqlalchemy import api as db_api
@@ -37,8 +36,8 @@ LOG = logging.getLogger(__name__)
 
 def _instance_group_get_query(context, id_field=None, id=None):
     query = context.session.query(api_models.InstanceGroup).\
-            options(joinedload('_policies')).\
-            options(joinedload('_members'))
+        options(orm.joinedload('_policies')).\
+        options(orm.joinedload('_members'))
     if not context.is_admin:
         query = query.filter_by(project_id=context.project_id)
     if id and id_field:
@@ -89,7 +88,7 @@ def _instance_group_members_add_by_uuid(context, group_uuid, members):
             outerjoin(api_models.InstanceGroupMember,
             api_models.InstanceGroupMember.instance_uuid.in_(set(members))).\
             filter(api_models.InstanceGroup.uuid == group_uuid).\
-            options(contains_eager('_members')).first()
+            options(orm.contains_eager('_members')).first()
     if not group:
         raise exception.InstanceGroupNotFound(group_uuid=group_uuid)
     return _instance_group_model_add(context, api_models.InstanceGroupMember,
diff --git a/nova/objects/instance_mapping.py b/nova/objects/instance_mapping.py
index 1358a67008f6..7da9c5df61ce 100644
--- a/nova/objects/instance_mapping.py
+++ b/nova/objects/instance_mapping.py
@@ -14,11 +14,10 @@ import collections
 
 from oslo_log import log as logging
 from oslo_utils import versionutils
+from sqlalchemy import orm
 from sqlalchemy.orm import exc as orm_exc
-from sqlalchemy.orm import joinedload
-from sqlalchemy.sql import false
+from sqlalchemy import sql
 from sqlalchemy.sql import func
-from sqlalchemy.sql import or_
 
 from nova import context as nova_context
 from nova.db.sqlalchemy import api as db_api
@@ -99,11 +98,10 @@ class InstanceMapping(base.NovaTimestampObject, base.NovaObject):
     @staticmethod
     @db_api.api_context_manager.reader
     def _get_by_instance_uuid_from_db(context, instance_uuid):
-        db_mapping = (context.session.query(api_models.InstanceMapping)
-                        .options(joinedload('cell_mapping'))
-                        .filter(
-                            api_models.InstanceMapping.instance_uuid ==
-                            instance_uuid)).first()
+        db_mapping = context.session.query(api_models.InstanceMapping)\
+            .options(orm.joinedload('cell_mapping'))\
+            .filter(api_models.InstanceMapping.instance_uuid == instance_uuid)\
+            .first()
         if not db_mapping:
             raise exception.InstanceMappingNotFound(uuid=instance_uuid)
 
@@ -313,10 +311,9 @@ class InstanceMappingList(base.ObjectListBase, base.NovaObject):
     @staticmethod
     @db_api.api_context_manager.reader
     def _get_by_project_id_from_db(context, project_id):
-        return (context.session.query(api_models.InstanceMapping)
-                .options(joinedload('cell_mapping'))
-                .filter(
-                    api_models.InstanceMapping.project_id == project_id)).all()
+        return context.session.query(api_models.InstanceMapping)\
+            .options(orm.joinedload('cell_mapping'))\
+            .filter(api_models.InstanceMapping.project_id == project_id).all()
 
     @base.remotable_classmethod
     def get_by_project_id(cls, context, project_id):
@@ -328,9 +325,9 @@ class InstanceMappingList(base.ObjectListBase, base.NovaObject):
     @staticmethod
     @db_api.api_context_manager.reader
     def _get_by_cell_id_from_db(context, cell_id):
-        return (context.session.query(api_models.InstanceMapping)
-                .options(joinedload('cell_mapping'))
-                .filter(api_models.InstanceMapping.cell_id == cell_id)).all()
+        return context.session.query(api_models.InstanceMapping)\
+            .options(orm.joinedload('cell_mapping'))\
+            .filter(api_models.InstanceMapping.cell_id == cell_id).all()
 
     @base.remotable_classmethod
     def get_by_cell_id(cls, context, cell_id):
@@ -341,10 +338,10 @@ class InstanceMappingList(base.ObjectListBase, base.NovaObject):
     @staticmethod
     @db_api.api_context_manager.reader
     def _get_by_instance_uuids_from_db(context, uuids):
-        return (context.session.query(api_models.InstanceMapping)
-                .options(joinedload('cell_mapping'))
-                .filter(api_models.InstanceMapping.instance_uuid.in_(uuids))
-                .all())
+        return context.session.query(api_models.InstanceMapping)\
+            .options(orm.joinedload('cell_mapping'))\
+            .filter(api_models.InstanceMapping.instance_uuid.in_(uuids))\
+            .all()
 
     @base.remotable_classmethod
     def get_by_instance_uuids(cls, context, uuids):
@@ -376,11 +373,11 @@ class InstanceMappingList(base.ObjectListBase, base.NovaObject):
         # queued_for_delete was not run) and False (cases when the online
         # data migration for queued_for_delete was run) are assumed to mean
         # that the instance is not queued for deletion.
-        query = (query.filter(or_(
-            api_models.InstanceMapping.queued_for_delete == false(),
+        query = (query.filter(sql.or_(
+            api_models.InstanceMapping.queued_for_delete == sql.false(),
             api_models.InstanceMapping.queued_for_delete.is_(None)))
             .join('cell_mapping')
-            .options(joinedload('cell_mapping'))
+            .options(orm.joinedload('cell_mapping'))
             .filter(api_models.CellMapping.uuid == cell_uuid))
         if limit is not None:
             query = query.limit(limit)
diff --git a/nova/quota.py b/nova/quota.py
index 29a0fc05e806..4c680bd1c153 100644
--- a/nova/quota.py
+++ b/nova/quota.py
@@ -20,10 +20,7 @@ import copy
 
 from oslo_log import log as logging
 from oslo_utils import importutils
-from sqlalchemy.sql import and_
-from sqlalchemy.sql import false
-from sqlalchemy.sql import null
-from sqlalchemy.sql import or_
+from sqlalchemy import sql
 
 import nova.conf
 from nova import context as nova_context
@@ -1077,13 +1074,13 @@ def _user_id_queued_for_delete_populated(context, project_id=None):
     :returns: True if user_id is set for all non-deleted instances and
               queued_for_delete is set for all instances, else False
     """
-    user_id_not_populated = and_(
-        api_models.InstanceMapping.user_id == null(),
-        api_models.InstanceMapping.queued_for_delete == false())
+    user_id_not_populated = sql.and_(
+        api_models.InstanceMapping.user_id == sql.null(),
+        api_models.InstanceMapping.queued_for_delete == sql.false())
     # If either queued_for_delete or user_id are unmigrated, we will return
     # False.
-    unmigrated_filter = or_(
-        api_models.InstanceMapping.queued_for_delete == null(),
+    unmigrated_filter = sql.or_(
+        api_models.InstanceMapping.queued_for_delete == sql.null(),
         user_id_not_populated)
     query = context.session.query(api_models.InstanceMapping).filter(
         unmigrated_filter)
diff --git a/nova/tests/functional/db/test_archive.py b/nova/tests/functional/db/test_archive.py
index 73f602fadceb..27ff5d5d5aed 100644
--- a/nova/tests/functional/db/test_archive.py
+++ b/nova/tests/functional/db/test_archive.py
@@ -18,9 +18,8 @@ import re
 from dateutil import parser as dateutil_parser
 from oslo_utils import fixture as osloutils_fixture
 from oslo_utils import timeutils
+import sqlalchemy as sa
 from sqlalchemy import func
-from sqlalchemy import MetaData
-from sqlalchemy import select
 
 from nova import context
 from nova.db import api as db
@@ -179,13 +178,13 @@ class TestDatabaseArchive(integrated_helpers._IntegratedTestBase):
     def _get_table_counts(self):
         engine = sqlalchemy_api.get_engine()
         conn = engine.connect()
-        meta = MetaData(engine)
+        meta = sa.MetaData(engine)
         meta.reflect()
         shadow_tables = sqlalchemy_api._purgeable_tables(meta)
         results = {}
         for table in shadow_tables:
             r = conn.execute(
-                select([func.count()]).select_from(table)).fetchone()
+                sa.select([func.count()]).select_from(table)).fetchone()
             results[table.name] = r[0]
         return results
 
diff --git a/nova/tests/unit/db/test_db_api.py b/nova/tests/unit/db/test_db_api.py
index c814e46a122a..ccce7106afda 100644
--- a/nova/tests/unit/db/test_db_api.py
+++ b/nova/tests/unit/db/test_db_api.py
@@ -36,16 +36,12 @@ from oslo_utils import fixture as utils_fixture
 from oslo_utils.fixture import uuidsentinel
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
-from sqlalchemy import Column
-from sqlalchemy.exc import OperationalError
-from sqlalchemy.exc import SQLAlchemyError
+import sqlalchemy as sa
+from sqlalchemy import exc as sqla_exc
 from sqlalchemy import inspect
-from sqlalchemy import Integer
-from sqlalchemy import MetaData
 from sqlalchemy.orm import query
 from sqlalchemy.orm import session as sqla_session
 from sqlalchemy import sql
-from sqlalchemy import Table
 
 from nova import block_device
 from nova.compute import rpcapi as compute_rpcapi
@@ -173,7 +169,7 @@ class DbTestCase(test.TestCase):
 
 
 class HelperTestCase(test.TestCase):
-    @mock.patch.object(sqlalchemy_api, 'joinedload')
+    @mock.patch('sqlalchemy.orm.joinedload')
     def test_joinedload_helper(self, mock_jl):
         query = sqlalchemy_api._joinedload_all('foo.bar.baz')
 
@@ -190,7 +186,7 @@ class HelperTestCase(test.TestCase):
 
         self.assertEqual(column3.joinedload.return_value, query)
 
-    @mock.patch.object(sqlalchemy_api, 'joinedload')
+    @mock.patch('sqlalchemy.orm.joinedload')
     def test_joinedload_helper_single(self, mock_jl):
         query = sqlalchemy_api._joinedload_all('foo')
 
@@ -1757,8 +1753,8 @@ class InstanceTestCase(test.TestCase, ModelsObjectComparatorMixin):
         instances = db.instance_get_all_by_filters_sort(self.ctxt, filters)
         self.assertEqual([], instances)
 
-    @mock.patch('nova.db.sqlalchemy.api.undefer')
-    @mock.patch('nova.db.sqlalchemy.api.joinedload')
+    @mock.patch('sqlalchemy.orm.undefer')
+    @mock.patch('sqlalchemy.orm.joinedload')
     def test_instance_get_all_by_filters_extra_columns(self,
                                                        mock_joinedload,
                                                        mock_undefer):
@@ -1768,8 +1764,8 @@ class InstanceTestCase(test.TestCase, ModelsObjectComparatorMixin):
         mock_joinedload.assert_called_once_with('info_cache')
         mock_undefer.assert_called_once_with('extra.pci_requests')
 
-    @mock.patch('nova.db.sqlalchemy.api.undefer')
-    @mock.patch('nova.db.sqlalchemy.api.joinedload')
+    @mock.patch('sqlalchemy.orm.undefer')
+    @mock.patch('sqlalchemy.orm.joinedload')
     def test_instance_get_active_by_window_extra_columns(self,
                                                          mock_joinedload,
                                                          mock_undefer):
@@ -2942,8 +2938,9 @@ class InstanceExtraTestCase(test.TestCase):
             self.ctxt, self.instance['uuid'],
             columns=['numa_topology', 'vcpu_model', 'trusted_certs',
                      'resources'])
-        self.assertRaises(SQLAlchemyError,
-                          extra.__getitem__, 'pci_requests')
+        self.assertRaises(
+            sqla_exc.SQLAlchemyError,
+            extra.__getitem__, 'pci_requests')
         self.assertIn('numa_topology', extra)
         self.assertIn('vcpu_model', extra)
         self.assertIn('trusted_certs', extra)
@@ -5899,7 +5896,7 @@ class ArchiveTestCase(test.TestCase, ModelsObjectComparatorMixin):
     def setUp(self):
         super(ArchiveTestCase, self).setUp()
         self.engine = get_engine()
-        self.metadata = MetaData(self.engine)
+        self.metadata = sa.MetaData(self.engine)
         self.conn = self.engine.connect()
         self.instance_id_mappings = models.InstanceIdMapping.__table__
         self.shadow_instance_id_mappings = sqlalchemyutils.get_table(
@@ -5931,7 +5928,7 @@ class ArchiveTestCase(test.TestCase, ModelsObjectComparatorMixin):
         except for specificially named exceptions, are empty. This
         makes sure that archiving isn't moving unexpected content.
         """
-        metadata = MetaData(bind=self.engine)
+        metadata = sa.MetaData(bind=self.engine)
         metadata.reflect()
         for table in metadata.tables:
             if table.startswith("shadow_") and table not in exceptions:
@@ -5943,7 +5940,7 @@ class ArchiveTestCase(test.TestCase, ModelsObjectComparatorMixin):
 
         Shadow tables should have an identical schema to the main table.
         """
-        metadata = MetaData(bind=self.engine)
+        metadata = sa.MetaData(bind=self.engine)
         metadata.reflect()
         for table_name in metadata.tables:
             # some tables don't have shadow tables so skip these
@@ -5961,8 +5958,8 @@ class ArchiveTestCase(test.TestCase, ModelsObjectComparatorMixin):
 
             shadow_table_name = f'shadow_{table_name}'
 
-            table = Table(table_name, metadata, autoload=True)
-            shadow_table = Table(shadow_table_name, metadata, autoload=True)
+            table = sa.Table(table_name, metadata, autoload=True)
+            shadow_table = sa.Table(shadow_table_name, metadata, autoload=True)
 
             columns = {c.name: c for c in table.columns}
             shadow_columns = {c.name: c for c in shadow_table.columns}
@@ -6159,7 +6156,7 @@ class ArchiveTestCase(test.TestCase, ModelsObjectComparatorMixin):
             ins_stmt = main_table.insert().values(uuid=uuidstr)
             try:
                 self.conn.execute(ins_stmt)
-            except (db_exc.DBError, OperationalError):
+            except (db_exc.DBError, sqla_exc.OperationalError):
                 # This table has constraints that require a table-specific
                 # insert, so skip it.
                 return 2
@@ -6640,12 +6637,12 @@ class TestSqlalchemyTypesRepr(
 
         super(TestSqlalchemyTypesRepr, self).setUp()
         self.engine = enginefacade.writer.get_engine()
-        meta = MetaData(bind=self.engine)
-        self.table = Table(
+        meta = sa.MetaData(bind=self.engine)
+        self.table = sa.Table(
             'cidr_tbl',
             meta,
-            Column('id', Integer, primary_key=True),
-            Column('addr', col_types.CIDR())
+            sa.Column('id', sa.Integer, primary_key=True),
+            sa.Column('addr', col_types.CIDR())
         )
         self.table.create()
         self.addCleanup(meta.drop_all)