diff --git a/nova/api/openstack/placement/objects/resource_provider.py b/nova/api/openstack/placement/objects/resource_provider.py
index c213dd6851c3..730bc201ad68 100644
--- a/nova/api/openstack/placement/objects/resource_provider.py
+++ b/nova/api/openstack/placement/objects/resource_provider.py
@@ -457,7 +457,6 @@ def _anchors_for_sharing_providers(context, rp_ids, get_id=False):
     # LEFT JOIN resource_providers AS rps
     #   ON shr_with_sps.root_provider_id = rps.id
     # WHERE sps.id IN $(RP_IDs)
-    # GROUP by shr_with_sps.root_provider_id
     rps = sa.alias(_RP_TBL, name='rps')
     sps = sa.alias(_RP_TBL, name='sps')
     shr_aggs = sa.alias(_RP_AGG_TBL, name='shr_aggs')
@@ -472,11 +471,15 @@ def _anchors_for_sharing_providers(context, rp_ids, get_id=False):
         join_chain, shr_with_sps,
         shr_with_sps_aggs.c.resource_provider_id == shr_with_sps.c.id)
     if get_id:
+        # TODO(yikun): Change `func.coalesce(shr_with_sps.c.root_provider_id,
+        # shr_with_sps.c.id)` to `shr_with_sps.c.root_provider_id` when we are
+        # sure all root_provider_id values are NOT NULL
         sel = sa.select([sps.c.id, func.coalesce(
             shr_with_sps.c.root_provider_id, shr_with_sps.c.id)])
     else:
-        # TODO(efried): Change this to an inner join when we are sure all
-        # root_provider_id values are NOT NULL
+        # TODO(efried): Change this to an inner join and change
+        # 'func.coalesce(rps.c.uuid, shr_with_sps.c.uuid)' to `rps.c.uuid`
+        # when we are sure all root_provider_id values are NOT NULL
         join_chain = sa.outerjoin(
             join_chain, rps, shr_with_sps.c.root_provider_id == rps.c.id)
         sel = sa.select([sps.c.uuid, func.coalesce(rps.c.uuid,
diff --git a/nova/tests/functional/api/openstack/placement/db/test_resource_provider.py b/nova/tests/functional/api/openstack/placement/db/test_resource_provider.py
index effc48b180a0..10b95b2d04e8 100644
--- a/nova/tests/functional/api/openstack/placement/db/test_resource_provider.py
+++ b/nova/tests/functional/api/openstack/placement/db/test_resource_provider.py
@@ -1041,7 +1041,7 @@ class TestResourceProviderAggregates(tb.PlacementDbBaseTestCase):
         # s1 gets s1 (self),
         # r1 via agg1 through c1,
         # r2 via agg2 AND via agg3 through c2
-        # r3 via agg2 and agg3
+        # r3 via agg3
         # s5 via agg1 and agg2
         expected = set([(s1.uuid, rp.uuid) for rp in (s1, r1, r2, r3, s5)])
         self.assertItemsEqual(