Average Active Sessions (AAS)

Cyrille Modiano

OCP Oracle DBA in Montreal at DBSoft

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The Average Active Sessions (AAS) metric is a very good indicator of the database activity.
This metric represents the number of sessions, either working or waiting for a resource at a specific point in time.
Idle sessions are not included in the calculation of this metric.
To calculate AAS, we need another metric called “DB Time” which represents the total time spent in the database by sessions, either working or waiting (The real work done in the database).
This DB time is divided by the clock elapsed time to obtain the Average Active Sessions.
The following script will calculate the Average Active Sessions from v$active_session_history view.

Be careful, this view is part of the diagnostic pack, you should not query this view if you don’t have license for it.

Average Active Sessions from v$active_session_history

You can restrict period of time analyzed by filtering with the sample_time column. Here is AAS from the last hour :

This metric can be correlated with the Graph from v$active_session_history

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