1 files changed, 6 insertions, 4 deletions
diff --git a/synapse/storage/databases/main/roommember.py b/synapse/storage/databases/main/roommember.py
index 2ed6ad754f..e56a13f21e 100644
--- a/synapse/storage/databases/main/roommember.py
+++ b/synapse/storage/databases/main/roommember.py
@@ -152,6 +152,9 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         the forward extremities of those rooms will exclude most members. We may also
         calculate room state incorrectly for such rooms and believe that a member is or
         is not in the room when the opposite is true.
+
+        Note: If you only care about users in the room local to the homeserver, use
+        `get_local_users_in_room(...)` instead which will be more performant.
         """
         return await self.db_pool.simple_select_onecol(
             table="current_state_events",
@@ -707,8 +710,8 @@ class RoomMemberWorkerStore(EventsWorkerStore):
 
         # 250 users is pretty arbitrary but the data can be quite large if users
         # are in many rooms.
-        for user_ids in batch_iter(user_ids, 250):
-            all_user_rooms.update(await self._get_rooms_for_users(user_ids))
+        for batch_user_ids in batch_iter(user_ids, 250):
+            all_user_rooms.update(await self._get_rooms_for_users(batch_user_ids))
 
         return all_user_rooms
 
@@ -742,7 +745,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
             # user and the set of other users, and then checking if there is any
             # overlap.
             sql = f"""
-                SELECT b.state_key
+                SELECT DISTINCT b.state_key
                 FROM (
                     SELECT room_id FROM current_state_events
                     WHERE type = 'm.room.member' AND membership = 'join' AND state_key = ?
@@ -751,7 +754,6 @@ class RoomMemberWorkerStore(EventsWorkerStore):
                     SELECT room_id, state_key FROM current_state_events
                     WHERE type = 'm.room.member' AND membership = 'join' AND {clause}
                 ) AS b using (room_id)
-                LIMIT 1
             """
 
             txn.execute(sql, (user_id, *args))