Improve filter_scheduler performance

Add 'columns_to_join' keyword arg to instance_get_all() and have the
scheduler host_manager only join 'instance_type'.  It doesn't use
anything else.

Fixes bug 1017769

Change-Id: Ia2c0956d2453f00e26eb89d9496a32ba15d970aa

2 files changed, 10 insertions, 9 deletions

diff --git a/nova/db/api.py b/nova/db/api.py
index e0d150506..6843412e5 100644
--- a/nova/db/api.py
+++ b/nova/db/api.py
@@ -563,9 +563,9 @@ def instance_get(context, instance_id):
     return IMPL.instance_get(context, instance_id)
 
 
-def instance_get_all(context):
+def instance_get_all(context, columns_to_join=None):
     """Get all instances."""
-    return IMPL.instance_get_all(context)
+    return IMPL.instance_get_all(context, columns_to_join=columns_to_join)
 
 
 def instance_get_all_by_filters(context, filters, sort_key='created_at',
diff --git a/nova/db/sqlalchemy/api.py b/nova/db/sqlalchemy/api.py
index eabd03a22..8d9687120 100644
--- a/nova/db/sqlalchemy/api.py
+++ b/nova/db/sqlalchemy/api.py
@@ -1435,13 +1435,14 @@ def _build_instance_get(context, session=None):
 
 
 @require_admin_context
-def instance_get_all(context):
-    return model_query(context, models.Instance).\
-                   options(joinedload('info_cache')).\
-                   options(joinedload('security_groups')).\
-                   options(joinedload('metadata')).\
-                   options(joinedload('instance_type')).\
-                   all()
+def instance_get_all(context, columns_to_join=None):
+    if columns_to_join is None:
+        columns_to_join = ['info_cache', 'security_groups',
+                           'metadata', 'instance_type']
+    query = model_query(context, models.Instance)
+    for column in columns_to_join:
+        query = query.options(joinedload(column))
+    return query.all()
 
 
 @require_context