AWR – automatic workload repository

to change the collection interval and retention policy

exec dbms_workload_repository.modify_snapshot_settings ( retention => 20160, -
interval => 30);

example above will change to 14 days (value in minutes) with 30mins snapshots

retention (default  8 days) and interval (default 1 hour)  in minutes

be aware – increasing the retention time or increase the frequence of snapshots the sysaux tablespace will increase also !

to show the current settings or the latest snapshot

col systimestamp format a35
col most_recent_snap_time format a25
col snap_interval format a17
col retention format a17

select systimestamp, most_recent_snap_time, snap_interval, retention
 from wrm$_wr_control 
  where dbid = (select dbid from v$database);

create manually a snapshot

exec dbms_workload_repository.create_snapshot

enable/disable Diagnostic&Tuning pack