1 files changed, 3 insertions, 0 deletions
diff --git a/synapse/storage/databases/main/registration.py b/synapse/storage/databases/main/registration.py
index 2ed696cc14..f949308994 100644
--- a/synapse/storage/databases/main/registration.py
+++ b/synapse/storage/databases/main/registration.py
@@ -41,6 +41,9 @@ class RegistrationWorkerStore(SQLBaseStore):
         self.config = hs.config
         self.clock = hs.get_clock()
 
+        # Note: we don't check this sequence for consistency as we'd have to
+        # call `find_max_generated_user_id_localpart` each time, which is
+        # expensive if there are many entries.
         self._user_id_seq = build_sequence_generator(
             database.engine, find_max_generated_user_id_localpart, "user_id_seq",
         )