Limit max number of SQL vars

synapse/storage/search.py

@@ -36,6 +36,8 @@ class SearchStore(SQLBaseStore):
         clauses = []
         args = []
 
+        # Make sure we don't explode because the person is in too many rooms.
+        if len(room_ids) > 500:
             clauses.append(
                 "room_id IN (%s)" % (",".join(["?"] * len(room_ids)),)
             )