all, I have a physical standby database, but a little error comes when open read only and again MRP apply. startup nomount; alter database mount standby database; alter database managed standby database disconnect from session; select open_mode from v$database; -- yield mount alter database managed standby database cancel; alter database open read only; select open_mode from v$database; -- yield read only -- back activate MRP alter database managed standby database disconnect from session; select open_mode from v$database; -- yield error, that v$database could not query -- but i can still query other v$ views, such as v$instance, v$datafile , etc -- regards ujang -- //www.freelists.org/webpage/oracle-l