The third domain of workload management is monitoring, which must be performed on an ongoing basis.
The primary purpose of monitoring is to validate the health and efficiency of your system and the individual workloads running on it. Using table functions, you can access real-time operational data such as a list of running workload occurrences and the activities running in a service class or average response times. Using event monitors you can capture detailed activity information and aggregate activity statistics for historical analysis.
Looking at aggregate information should usually be the first step when you build a monitoring strategy. Aggregates give a good picture of overall data server activity and are also cheaper because you do not have to collect information on every activity in which you might be interested. You can collect more detailed information as you understand the scope of your monitoring needs.