As mentioned earlier, the MMON writes statistics from memory to disk in the AWR in what is known as a Snapshot. The MMON Background Process also generates ADDM Reports on activities and potential issues between this Snapshot and the Snapshot preceding it.

The ADDM Reports are reports that are automatically generated after taking an AWR Snapshot. These reports highlight issues in the database and suggest recommendations and solutions. However, in most cases, these recommendations include suggestions that were issued by other consultants, from whom you can obtain more detailed information from the ADDM.

The automatically generated ADDM Reports cover the period between the current Snapshot and the previous Snapshot. However, of course, you can manually generate ADDM Reports.

ADDM Reports are launched through the MMON Background Process, and ADDM Reports are typically deleted after 30 days.

You can view ADDM Reports in detail through the Enterprise Manager.

You mentioned that AWR Snapshots are taken every hour and these Snapshots are retained for seven days. However, the database administrator can change this configuration through the MODIFY_SNAPSHOT_SETTINGS procedure in the DBMS_WORKLOAD_REPOSITORY package.

BEGIN
DBMS_WORKLOAD_REPOSITORY.MODIFY_SNAPSHOT_SETTINGS(
RETENTION => 20160,
INTERVAL => 30);
END;
/

This way, I have changed the AWR Snapshot configuration where the Snapshot is taken every half hour and retained for two weeks.

The database administrator can revert to the default configuration by executing the MODIFY_SNAPSHOT_SETTINGS procedure with NULL values for both variables.