1 files changed, 8 insertions, 4 deletions
diff --git a/synapse/util/caches/stream_change_cache.py b/synapse/util/caches/stream_change_cache.py
index 91c335f85b..16fcb00206 100644
--- a/synapse/util/caches/stream_change_cache.py
+++ b/synapse/util/caches/stream_change_cache.py
@@ -327,7 +327,7 @@ class StreamChangeCache:
             for entity in r:
                 self._entity_to_key.pop(entity, None)
 
-    def get_max_pos_of_last_change(self, entity: EntityType) -> int:
+    def get_max_pos_of_last_change(self, entity: EntityType) -> Optional[int]:
         """Returns an upper bound of the stream id of the last change to an
         entity.
 
@@ -335,7 +335,11 @@ class StreamChangeCache:
             entity: The entity to check.
 
         Return:
-            The stream position of the latest change for the given entity or
-            the earliest known stream position if the entitiy is unknown.
+            The stream position of the latest change for the given entity, if
+            known
         """
-        return self._entity_to_key.get(entity, self._earliest_known_stream_pos)
+        return self._entity_to_key.get(entity)
+
+    def get_earliest_known_position(self) -> int:
+        """Returns the earliest position in the cache."""
+        return self._earliest_known_stream_pos