Why would you use Active Session History if you already have AWR and ADDM? This session gives an overview of what is ASH and how to use it to monitor the database and detect performance issues. We briefly introduce the ASH architecture and how to access the data gathered by ASH, with stress on things that are not readily available on the OEM ASH analytics page.

As of Oracle 23c, V$ACTIVE_SESSION_HISTORY has 115 columns. We give an overview of what has been exposed through ASH. Which are more exciting areas in ASH? Is there something not yet included in ASH?

ASH gathers samples of the database activity, meaning that database load and SQL response times have to be estimated from the samples. We show how to estimate the number of active sessions correctly. What is the connection between average active sessions and query response time?

When SQL execution takes minutes, arriving at the correct response time isn't a problem. But what do we do if SQL response times are much less than a sampling interval? There's a way to estimate those response times from ASH as well.

This is beginner to intermediate level talk, with some advanced bits around the response time estimation. Preferred duration of the talk is 45 minutes.