Ticket #11039: 10870_patch_against_10706.diff

ref/contrib/contenttypes.txt

@@ -339 +342 @@
 if a ``Bookmark`` object were deleted, any ``TaggedItem`` objects pointing at
 it would be deleted at the same time.
 
+.. note::
+
+    You can't currently use :ref:`Django's database aggregation API
+    <topics-db-aggregation` with a
+    :class:`~django.contrib.contenttypes.generic.GenericRelation`. For
+    example, you might be tempted to try something like::
+
+        Bookmark.objects.aggregate(Count('tags'))
+        
+    This will not work correctly, however. The generic relation adds
+    extra filters to the queryset to ensure the correct content type,
+    but the ``aggregate`` method doesn't take them into account. For
+    now, if you need aggregates on generic relations, you'll need to
+    calculate them without using the aggregation API.
+
 Generic relations in forms and admin
 ------------------------------------