diff --git a/data/model/repository.py b/data/model/repository.py
index 24199c00b..c518fc5f7 100644
--- a/data/model/repository.py
+++ b/data/model/repository.py
@@ -119,21 +119,30 @@ def garbage_collect_repo(repo):
                      .join(RepositoryTag)
                      .where(Image.repository == repo))
 
-    referenced_ancestors = set()
-    for tagged_image in tagged_images:
-      # The ancestor list is in the format '/1/2/3/', extract just the ids
-      ancestor_id_strings = tagged_image.ancestors.split('/')[1:-1]
-      ancestor_list = [int(img_id_str) for img_id_str in ancestor_id_strings]
-      referenced_ancestors = referenced_ancestors.union(set(ancestor_list))
-      referenced_ancestors.add(tagged_image.id)
+    def gen_referenced_ancestors():
+      for tagged_image in tagged_images:
+        # The ancestor list is in the format '/1/2/3/', extract just the ids
+        ancestor_id_strings = tagged_image.ancestors.split('/')[1:-1]
+        for img_id_str in ancestor_id_strings:
+          yield int(img_id_str)
+        yield tagged_image.id
 
-    all_repo_images = Image.select(Image.id, Image.storage).where(Image.repository == repo)
-    all_images = {int(img.id): img for img in all_repo_images}
-    to_remove = set(all_images.keys()).difference(referenced_ancestors)
+    referenced_ancestors = set(gen_referenced_ancestors())
+
+    # We desire two pieces of information from the database from the following
+    # query: all of the image ids which are associated with this repository,
+    # and the storages which are associated with those images. In order to
+    # fetch just this information, and bypass all of the peewee model parsing
+    # code, which is overkill for just two fields, we use a tuple query, and
+    # feed that directly to the dictionary tuple constructor which takes an
+    # iterable of tuples containing [(k, v), (k, v), ...]
+    all_repo_images = Image.select(Image.id, Image.storage).where(Image.repository == repo).tuples()
+    images_to_storages = dict(all_repo_images)
+    to_remove = set(images_to_storages.keys()).difference(referenced_ancestors)
 
     if len(to_remove) > 0:
       logger.info('Cleaning up unreferenced images: %s', to_remove)
-      storage_id_whitelist = {all_images[to_remove_id].storage_id for to_remove_id in to_remove}
+      storage_id_whitelist = {images_to_storages[to_remove_id] for to_remove_id in to_remove}
       Image.delete().where(Image.id << list(to_remove)).execute()
 
   if len(to_remove) > 0: