Jak zjistit log file sync

Jednoduché je zjištění hodnoty log file sync z AWR reportu, ale pokud si chcete zobrazit hodnotu log file sync v čase tak je to jednoduché pomocí AWR tabulek

select c.BEGIN_INTERVAL_TIME,((b.time_waited_micro-a.time_waited_micro)/1000)/(b.TOTAL_WAITS-a.TOTAL_WAITS) "log file sync (ms)" 
from dba_hist_system_event a ,dba_hist_system_event b,dba_hist_snapshot c 
where a.SNAP_ID=c.SNAP_ID and a.DBID=c.DBID and a.INSTANCE_NUMBER=c.INSTANCE_NUMBER 
and a.SNAP_ID=b.SNAP_ID-1 and a.DBID=b.DBID and a.INSTANCE_NUMBER=b.INSTANCE_NUMBER 
and a.EVENT_ID=b.EVENT_ID and a.EVENT_NAME='log file sync' order by 1;