The actual dynamic performance views are identified by the prefix V_$. Public synonyms for these views have the prefix V$. Database administrators and other users should access only the V$ objects, not the V_$ objects.
The dynamic performance views are used by Oracle Enterprise Manager, which is the primary interface for accessing information about system performance. After an instance is started, the V$ views that read from memory are accessible. Views that read data from disk require that the database be mounted, and some require that the database be open.
V$ views are CONTAINER_DATA objects. When a user connected to the root queries a V$ view, the query results will depend on the CONTAINER_DATA attribute for users for the view. The CONTAINER_DATA clause of the SQL ALTER USER statement is used to set and modify users' CONTAINER_DATA attribute.
See Also:
Oracle Database Security Guide for more information about container data objects
Oracle Database SQL Language Reference for more information about the CONTAINER_DATA clause for the SQL ALTER USER statement