An instance can be started in (or later altered to be in) restricted mode so that when the database is open connections are limited only to those whose user accounts have been granted the RESTRICTED SESSION system privilege.
When the database is started in restricted session mode only users(such as those with roleDBA) with the system privilege RESTRICTED SESSION can connect to the database. Use the restricted mode when performing maintenance or when you want certain users to be able to log in.
An Instance Can be started in restricted mode.So that when the db is open connections are limited to only those user accounts have been granted restricted session system privilege.
RESTRICT is one of an important option used with an open database. It performs a database startup with the database in the restricted user mode. User must having the privileges of RESTRICT usually it is used by DBA's only.
It is used for database maintenence allowing only DBA's to connect and disallowing general user population activity.
We can change this mode by using the ALTER DATABASE [RESTRICT] OPEN command.
