How to increase the AWR retention to 32 days?

Check the current retention: 

select retention from dba_hist_wr_control;

RETENTION

---------------------------------------------------------------------------

+00008 00:00:00.0

Change it to 32 days: NOTE: the retention value is in seconds. 32days*24hours*60sec

exec dbms_workload_repository.modify_snapshot_settings (retention => 46080);

PL/SQL procedure successfully completed.

Check the new retention: 

select retention from dba_hist_wr_control;

RETENTION

---------------------------------------------------------------------------

+00032 00:00:00.0