Explanation/Reference:
Explanation:
The Automatic Workload Repository (AWR) collects, processes, and maintains performance statistics for problem detection and self-tuning purposes. This data is both in memory and stored in the database. The gathered data can be displayed in both reports and views.
The statistics collected and processed by AWR include:
V$SYS_TIME_MODEL and V$SESS_TIME_MODEL views
V$SESSTAT views
Activity
MMON (Memory Monitor) is a background process that gathers memory statistics (snapshots) stores this information in the AWR (automatic workload repository). MMON is also responsible for issuing alerts for metrics that exceed their thresholds.
Oracle Database Performance Tuning Guide