dba_hist_bg_event_summary records snapshots from v$session_event or background event activity.
select
snp_id,
to_char(int_beg, 'yyyy-mm-dd hh24:mi:ss') int_beg,
to_char(int_end, 'yyyy-mm-dd hh24:mi:ss') int_end,
cls,
evt,
to_char((twm_act - twm_prev) / 1000, '99,999,990.000') tw_mil_s,
waits_act - waits_prev waits,
tmouts_act - tmouts_prev tmouts
-- twm_act, twm_prev
from
(
select
snp.snap_id snp_id,
snp.begin_interval_time int_beg,
snp.end_interval_time int_end,
bge.event_name evt,
bge.wait_class cls,
--
bge.time_waited_micro twm_act,
bge.total_waits waits_act,
bge.total_timeouts tmouts_act,
--
lag(bge.time_waited_micro) over (partition by bge.event_id order by bge.snap_id) twm_prev,
lag(bge.total_waits ) over (partition by bge.event_id order by bge.snap_id) waits_prev,
lag(bge.total_timeouts ) over (partition by bge.event_id order by bge.snap_id) tmouts_prev
from
dba_hist_snapshot snp left join
dba_hist_bg_event_summary bge on bge.snap_id = snp.snap_id and bge.dbid = snp.dbid
)
where
timestamp '2026-03-04 11:05:00' between int_beg and int_end
order by
twm_act - twm_prev desc;