Oracle Dynamic Performance Views

Oracle dynamic performance views (v$) are built on the virtual tables ($x). The views (v$) are much more useful than the virtual tables ($x). To get a listing of all them use the following query:

select

 NAME

from 

 V$FIXED_TABLE

where 

 TYPE = 'VIEW';

Some of the most useful views include:

v$database Details about the nature and state of the database

v$transaction What transactions are currently uncommitted

v$session What users have logged on

v$controlfile Names and locations of all control files

v$logfile Names and locations of all online redo logs

v$datafile Names and locations of all data files

v$instance Details about the nature and state of the instance

v$sqltext What queries are users issuing

v$process What background and server processes are running

Global dynamic performance views have the prefix gv$. They are viewing across all instances when using a real application cluster (RAC) configuration.