When administrating a RAC system use the dictionary views of GV$ and not V$.
GV$ has additional columns inst_id .
For almost every
V$ view described in this chapter, Oracle has a corresponding
V$) view. In Real Application Clusters, querying a
GV$ view retrieves the
V$ view information from all qualified instances.
In addition to the
V$ information, each
GV$ view contains an extra column named
INST_ID of datatype
INST_ID column displays the instance number from which the associated
V$ view information was obtained. The
INST_ID column can be used as a filter to retrieve
V$information from a subset of available instances
|Across all the nodes:
The beauty of system dictionary views of GV$ which reflect information across the various nodes of a RAC system
|Only the current node
The V$ views of the data dictionary, which relate to the current status of the single node you are connected to
|select distinct(username) from v$session;|
It only reflects connections to the connected node and not the entire RAC.
|select distinct(username) from gv$session;|
It gives the view of all sessions within the RAC.
The GV$ dictionary views have the additional INST_ID column which give the node that the action is occurring in