Oracle’s dynamic performance views are available to monitor OPS-related activities and are referred to as V$ views. These views display Oracle server performance data from internal data structures of the Oracle instance and are continuously updated. Each OPS instance has its own set of performance data and hence has its own set of V$ views. Some of these views are OPS-specific. To create the OPS-specific views, you have to run the SQL script catparr.sql while you are logged in as the user SYS. Normally, you would do this when you first create an OPS database, but you can run catparr.sql at any time. In Unix environments, the catparr.sql script is located in the $ORACLE_HOME/rdbms/admin directory.

Global dynamic performance views, referred to as GV$ views, have been available since the release of Oracle8. The GV$ views have the same columns as the V$ views, plus an additional instance identifier (INST_ID) column. These views return performance information for all instances opening an OPS database and allow an administrator to monitor most OPS performance statistics centrally. No matter which instance you are connected to, you can use the GV$ views to retrieve statistics for any other instance, for example:

SELECT * 
FROM gv$ping 
WHERE inst_id = 2;