redo apply

You can specify that Redo Apply runs as a foreground session or as a background process, and enable it with real-time apply.
To start Redo Apply in the foreground, issue the following SQL statement:
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE;
If you start a foreground session, control is not returned to the command prompt until recovery is canceled by another session.
To start Redo Apply in the background, include the DISCONNECT keyword on the SQL statement. For example:
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT;
This statement starts a detached server process and immediately returns control to the user. While the managed recovery process is performing recovery in the background, the foreground process that issued the RECOVER statement can continue performing other tasks. This does not disconnect the current SQL session.
To start real-time apply, include the USING CURRENT LOGFILE clause on the SQL statement. For example:
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE;

http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/log_apply.htm