7 Manual Database Performance Monitoring
You can run the Automatic Database Diagnostic Monitor (ADDM) manually to monitor current and historical database performance. Typically, you use the automatic diagnostic feature of ADDM to identify performance problems with the database. As described in Automatic Database Performance Monitoring, ADDM runs once every hour by default. You can configure ADDM to run at a different time interval. However, in some cases you may want to run ADDM manually.
You can run ADDM manually to analyze a time period that is longer than one ADDM analysis period. For example, you may want to analyze database performance in a workday by analyzing 8 consecutive hours. You could analyze each of the individual ADDM periods within the workday, but this approach may become complicated if performance problems appear in only some ADDM periods. Alternatively, you can run ADDM manually with a pair of Automatic Workload Repository (AWR) snapshots that encompass the 8-hour period. In this case, ADDM identifies the most critical performance problems in the entire time period.
This chapter contains the following sections: