The problem of Shutdown

there will be time when an application is coded with a detached process running. The detached process makes a connection to your database and maintains that connection indefinitely. There are many valid reasons to have an application process do this.

However, a problem arises when you need to shut down your database. You won't be able to perform a normal shutdown because the application process is running and the database will wait until all processes have disconnected before the shutdown is completed.

There are two ways to solve this problem. You can make it a policy always to do a shutdown immediate, or you can have your developers use the v$instance view to determine whether your database is waiting to shut down by checking the shutdown_pending column. If this column value changes from NO to YES, the application can be coded to automatically disconnect from the database. You will, of course, have to give the application user the privilege to select from this view