diff --git a/zun/db/sqlalchemy/alembic/versions/33cdd98bb9b2_split_volume_mapping_table.py b/zun/db/sqlalchemy/alembic/versions/33cdd98bb9b2_split_volume_mapping_table.py
index 97a3c46a4..2762e87ad 100644
--- a/zun/db/sqlalchemy/alembic/versions/33cdd98bb9b2_split_volume_mapping_table.py
+++ b/zun/db/sqlalchemy/alembic/versions/33cdd98bb9b2_split_volume_mapping_table.py
@@ -92,8 +92,7 @@ def update_existing_records():
                             nullable=True))
 
     # perform data migration between tables
-    session = sa.orm.Session(bind=op.get_bind())
-    with session.begin(subtransactions=True):
+    with sa.orm.Session(bind=op.get_bind()) as session:
         for row in session.query(VOLUME_MAPPING_TABLE):
             res = session.execute(
                 VOLUME_TABLE.insert().values(
@@ -112,8 +111,8 @@ def update_existing_records():
                     volume_id=res.inserted_primary_key[0]).where(
                         VOLUME_MAPPING_TABLE.c.id == row.id)
             )
-    # this commit is necessary to allow further operations
-    session.commit()
+        # this commit is necessary to allow further operations
+        session.commit()
 
     op.alter_column('volume_mapping', 'volume_id',
                     nullable=False,
diff --git a/zun/db/sqlalchemy/alembic/versions/3e80bbfd8da7_convert_type_of_command_from_string_to_.py b/zun/db/sqlalchemy/alembic/versions/3e80bbfd8da7_convert_type_of_command_from_string_to_.py
index 4ee5cdcc5..20056e469 100644
--- a/zun/db/sqlalchemy/alembic/versions/3e80bbfd8da7_convert_type_of_command_from_string_to_.py
+++ b/zun/db/sqlalchemy/alembic/versions/3e80bbfd8da7_convert_type_of_command_from_string_to_.py
@@ -43,8 +43,7 @@ TABLE_MODEL = sa.Table(
 def upgrade():
     op.alter_column('container', 'command', type_=sa.Text())
     # Convert 'command' from string to json-encoded list
-    session = sa.orm.Session(bind=op.get_bind())
-    with session.begin(subtransactions=True):
+    with sa.orm.Session(bind=op.get_bind()) as session:
         for row in session.query(TABLE_MODEL):
             if row[1]:
                 command = shlex.split(row[1])
@@ -53,4 +52,4 @@ def upgrade():
                     TABLE_MODEL.update().values(
                         command=command).where(
                             TABLE_MODEL.c.id == row[0]))
-    session.commit()
+        session.commit()
diff --git a/zun/db/sqlalchemy/alembic/versions/d502ce8fb705_add_rp_uuid_to_compute_node.py b/zun/db/sqlalchemy/alembic/versions/d502ce8fb705_add_rp_uuid_to_compute_node.py
index 80cfcee7d..ee213094d 100644
--- a/zun/db/sqlalchemy/alembic/versions/d502ce8fb705_add_rp_uuid_to_compute_node.py
+++ b/zun/db/sqlalchemy/alembic/versions/d502ce8fb705_add_rp_uuid_to_compute_node.py
@@ -41,16 +41,15 @@ def upgrade():
                                 'compute_node', ['rp_uuid'])
 
     # perform data migration between tables
-    session = sa.orm.Session(bind=op.get_bind())
-    with session.begin(subtransactions=True):
+    with sa.orm.Session(bind=op.get_bind()) as session:
         for row in session.query(COMPUTE_NODE_TABLE):
             session.execute(
                 COMPUTE_NODE_TABLE.update().values(
                     rp_uuid=row.uuid).where(
                         COMPUTE_NODE_TABLE.c.uuid == row.uuid)
             )
-    # this commit is necessary to allow further operations
-    session.commit()
+        # this commit is necessary to allow further operations
+        session.commit()
 
     op.alter_column('compute_node', 'rp_uuid',
                     nullable=False,
diff --git a/zun/db/sqlalchemy/api.py b/zun/db/sqlalchemy/api.py
index 38f6155bf..d80860dab 100644
--- a/zun/db/sqlalchemy/api.py
+++ b/zun/db/sqlalchemy/api.py
@@ -760,7 +760,8 @@ class Connection(object):
             query = model_query(models.Inventory, session=session)
             query = self._add_inventories_filters(query, filters)
             query = query.join(models.Inventory.resource_provider)
-            query = query.options(contains_eager('resource_provider'))
+            query = query.options(
+                contains_eager(models.Inventory.resource_provider))
             return _paginate_query(models.Inventory, limit, marker,
                                    sort_key, sort_dir, query)
 
@@ -783,7 +784,8 @@ class Connection(object):
             session = get_session()
             query = model_query(models.Inventory, session=session)
             query = query.join(models.Inventory.resource_provider)
-            query = query.options(contains_eager('resource_provider'))
+            query = query.options(
+                contains_eager(models.Inventory.resource_provider))
             query = query.filter_by(id=inventory_id)
             try:
                 return query.one()
@@ -825,7 +827,8 @@ class Connection(object):
             query = model_query(models.Allocation, session=session)
             query = self._add_allocations_filters(query, filters)
             query = query.join(models.Allocation.resource_provider)
-            query = query.options(contains_eager('resource_provider'))
+            query = query.options(
+                contains_eager(models.Allocation.resource_provider))
             return _paginate_query(models.Allocation, limit, marker,
                                    sort_key, sort_dir, query)
 
@@ -846,7 +849,8 @@ class Connection(object):
         with session.begin():
             query = model_query(models.Allocation, session=session)
             query = query.join(models.Allocation.resource_provider)
-            query = query.options(contains_eager('resource_provider'))
+            query = query.options(
+                contains_eager(models.Allocation.resource_provider))
             query = query.filter_by(id=allocation_id)
             try:
                 return query.one()