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Title
What are Average Active Sessions in a database agent workload? -
Description
Database agents use "Average Active Sessions" to display the workload. What is this?
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Cause
Average Active Sessions (AAS) metric is often used as an indicator of database activity to provide a sense of how busy a monitored database instance is and the workload that is happening.
The metric represents the number of sessions that are either working or waiting for a resource at a specific point in time.
Idle sessions are not included in the calculation of this metric.
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Resolution
An Active Session is a SQL Server session that is currently spending time in a database call (e.g. a SQL query).
Average Active Sessions (AAS) is the ratio of the change in Database Time (time in the database in seconds spent using CPU, IO, waiting) divided by the clock time. It is not a measure of how many sessions exist in the system at a given time, but rather how busy the database is. The metric of Seconds per Second (Seconds/S) is taken with the context of how an object changes acceleration (speeding up or down).
Seconds/s stands for seconds DB workload per one second. In one second a Database does the work of (for example) five seconds, as it works with more than one core and in parallel. Seconds/s is the term in Oracle as well.The AAS are compared with the CPU count on the monitored host
- When the AAS is higher than the number of CPUs in the system, then there may be performance issues that require investigation.
A user would then look identify the type of wait and SQL statement which was the primary cause for the high system resource utilization.