Disable statement timeout during room purge

Author: MatMaul

synapse/storage/databases/main/purge_events.py

@@ -376,6 +376,11 @@ def _purge_room_txn(self, txn: LoggingTransaction, room_id: str) -> List[int]:
                 (room_id,),
             )
 
+        if isinstance(self.database_engine, PostgresEngine):
+            # Disable statement timeouts for this transaction; purging rooms can
+            # take a while!
+            txn.execute("SET LOCAL statement_timeout = 0")
+
         # First, fetch all the state groups that should be deleted, before
         # we delete that information.
         txn.execute(