All of these performance views have names that begin with V$, and, from
Oracle9i on, there are also global views (for all nodes in a Real Application Clusters
or RAC database) that begin with GV$. Two views, in particular, identify the sources
of these waits; these are invaluable for guiding your analysis:
V$SYSTEM_EVENT
Provides aggregated, systemwide information about the resources for which the
whole instance is waiting
V$SESSION_EVENT
Provides cumulative list of events waited for in each session
V$SESSION_WAIT
Provides detailed, session-specific information about the resources for which
individual sessions are currently waiting or last waited for
V$SESSION
Provides session information for each current session including event currently
or last waited for
You can use these views to pinpoint the resources that are causing the most waits.
Focusing on the resources causing the most waiting can provide large performance
improvements.
Oracle Database 10g and newer releases provide an enhanced wait
model that makes it easier to determine exactly who is waiting for
what resource at what time.
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