AWR load spikes

AWR query to find load spikes
select
to_char(round(sub1.sample_time, ‘HH24′), ‘YYYY-MM-DD HH24:MI’) as sample_hour,
round(avg(sub1.on_cpu),1) as cpu_avg,
round(avg(sub1.waiting),1) as wait_avg,
round(avg(sub1.active_sessions),1) as act_avg,
round( (variance(sub1.active_sessions)/avg(sub1.active_sessions)),1) as act_var_mean
from
( — sub1: one row per ASH/AWR sample observation
select
sample_id,
sample_time,
sum(decode(session_state, ‘ON CPU’, 1, 0))  as on_cpu,
sum(decode(session_state, ‘WAITING’, 1, 0)) as waiting,
count(*) as active_sessions
from
dba_hist_active_sess_history
where
sample_time > sysdate – (&hours/24)
group by
sample_id,
sample_time
) sub1
group by
round(sub1.sample_time, ‘HH24′)
order by
round(sub1.sample_time, ‘HH24′)
;