if we're loading a course module with depth = 0, then we don't need to…

if we're loading a course module with depth = 0, then we don't need to fetch/compute inherited metadata

common/lib/xmodule/xmodule/modulestore/mongo.py

@@ -376,7 +376,7 @@ class MongoModuleStore(ModuleStoreBase):
 
         return data
 
-    def _load_item(self, item, data_cache):
+    def _load_item(self, item, data_cache, depth=0):
         """
         Load an XModuleDescriptor from item, using the children stored in data_cache
         """
@@ -388,7 +388,11 @@ class MongoModuleStore(ModuleStoreBase):
 
         resource_fs = OSFS(root)
 
-        metadata_inheritance_tree = self.get_cached_metadata_inheritance_tree(Location(item['location']))
+        metadata_inheritance_tree = None
+        # if we are loading a course object, if we're not prefetching children (depth != 0) then don't
+        # bother with the metadata inheritence 
+        if item['location']['category'] != 'course' or depth != 0:
+            metadata_inheritance_tree = self.get_cached_metadata_inheritance_tree(Location(item['location']))
 
         # TODO (cdodge): When the 'split module store' work has been completed, we should remove
         # the 'metadata_inheritance_tree' parameter
@@ -410,7 +414,7 @@ class MongoModuleStore(ModuleStoreBase):
         """
         data_cache = self._cache_children(items, depth)
 
-        return [self._load_item(item, data_cache) for item in items]
+        return [self._load_item(item, data_cache, depth) for item in items]
 
     def get_courses(self):
         '''