Add perf comments

data/model/legacy.py

@@ -1148,6 +1148,8 @@ def __translate_ancestry(old_ancestry, translations, repository, username, prefe
 
     return translations[old_id]
 
+  # TODO: PERFORMANCE IMPROVMENT: Select all the ancestor Docker IDs in a single query. The values
+  # are retrieved in the above translate call.
   old_ids = [int(id_str) for id_str in old_ancestry.split('/')[1:-1]]
   new_ids = [str(translate_id(old_id)) for old_id in old_ids]
   return '/%s/' % '/'.join(new_ids)
@@ -1164,6 +1166,9 @@ def _create_storage(location_name):
 def find_create_or_link_image(docker_image_id, repository, username, translations,
                               preferred_location):
   with config.app_config['DB_TRANSACTION_FACTORY'](db):
+    # TODO PERF IMPROVEMENT: Also make this only lookup the image directly, rather than
+    # joining image and image storage, etc. The common case doesn't need that information
+    # (but other callers might, so double check)
     repo_image = get_repo_image(repository.namespace_user.username, repository.name,
                                 docker_image_id)
     if repo_image: