diff --git a/vmware_nsx/db/db.py b/vmware_nsx/db/db.py
index 4267786d2c..ec8be03d7d 100644
--- a/vmware_nsx/db/db.py
+++ b/vmware_nsx/db/db.py
@@ -330,19 +330,6 @@ def delete_neutron_nsx_router_mapping(session, neutron_id):
         session, nsx_models.NeutronNsxRouterMapping, neutron_id)
 
 
-def unset_default_network_gateways(session):
-    with session.begin(subtransactions=True):
-        session.query(nsx_models.NetworkGateway).update(
-            {nsx_models.NetworkGateway.default: False})
-
-
-def set_default_network_gateway(session, gw_id):
-    with session.begin(subtransactions=True):
-        gw = (session.query(nsx_models.NetworkGateway).
-              filter_by(id=gw_id).one())
-        gw['default'] = True
-
-
 def set_multiprovider_network(session, network_id):
     with session.begin(subtransactions=True):
         multiprovider_network = nsx_models.MultiProviderNetworks(
@@ -402,29 +389,6 @@ def delete_qos_policy_profile_mapping(session, qos_policy_id):
             filter_by(qos_policy_id=qos_policy_id).delete())
 
 
-# NSXv3 Port Mirror Sessions DB methods.
-def add_port_mirror_session_mapping(session, tf_id, pm_session_id):
-    with session.begin(subtransactions=True):
-        mapping = nsx_models.NsxPortMirrorSessionMapping(
-            tap_flow_id=tf_id,
-            port_mirror_session_id=pm_session_id)
-        session.add(mapping)
-        return mapping
-
-
-def get_port_mirror_session_mapping(session, tf_id):
-    try:
-        return (session.query(nsx_models.NsxPortMirrorSessionMapping).
-                filter_by(tap_flow_id=tf_id).one())
-    except exc.NoResultFound:
-        raise nsx_exc.NsxPortMirrorSessionMappingNotFound(tf=tf_id)
-
-
-def delete_port_mirror_session_mapping(session, tf_id):
-    return (session.query(nsx_models.NsxPortMirrorSessionMapping).
-            filter_by(tap_flow_id=tf_id).delete())
-
-
 @db_api.CONTEXT_WRITER
 def save_sg_mappings(context, sg_id, nsgroup_id, section_id):
     context.session.add(
diff --git a/vmware_nsx/db/nsx_models.py b/vmware_nsx/db/nsx_models.py
index b655bc6bed..cdebec343a 100644
--- a/vmware_nsx/db/nsx_models.py
+++ b/vmware_nsx/db/nsx_models.py
@@ -217,6 +217,7 @@ class NetworkConnection(model_base.BASEV2, model_base.HasProject,
 
 
 class NetworkGatewayDeviceReference(model_base.BASEV2, models.TimestampMixin):
+    # This table is no longer in use
     id = sa.Column(sa.String(36), primary_key=True)
     network_gateway_id = sa.Column(sa.String(36),
                                    sa.ForeignKey('networkgateways.id',
@@ -227,6 +228,7 @@ class NetworkGatewayDeviceReference(model_base.BASEV2, models.TimestampMixin):
 
 class NetworkGatewayDevice(model_base.BASEV2, model_base.HasId,
                            model_base.HasProject, models.TimestampMixin):
+    # This table is no longer in use
     nsx_id = sa.Column(sa.String(36))
     # Optional name for the gateway device
     name = sa.Column(sa.String(255))
@@ -242,6 +244,7 @@ class NetworkGatewayDevice(model_base.BASEV2, model_base.HasId,
 class NetworkGateway(model_base.BASEV2, model_base.HasId,
                      model_base.HasProject, models.TimestampMixin):
     """Defines the data model for a network gateway."""
+    # This table is no longer in use
     name = sa.Column(sa.String(255))
     default = sa.Column(sa.Boolean())
     devices = orm.relationship(NetworkGatewayDeviceReference,
@@ -317,6 +320,7 @@ class QosPolicySwitchProfile(model_base.BASEV2, models.TimestampMixin):
 
 class NsxPortMirrorSessionMapping(model_base.BASEV2):
     """Define a mapping between Tap Flow and PortMirrorSession object."""
+    # This table is no longer in use
     __tablename__ = 'nsx_port_mirror_session_mappings'
     tap_flow_id = sa.Column(sa.String(36),
                             nullable=False,