Redo Log Switches Per Hour

SET PAGESIZE 60
SET LINESIZE 300

SELECT to_char(first_time, 'yyyy - mm - dd') aday,
           to_char(first_time, 'hh24') hour,
           count(*) total
FROM   v$log_history
WHERE  thread#=&EnterThreadId
GROUP BY to_char(first_time, 'yyyy - mm - dd'),
              to_char(first_time, 'hh24')
ORDER BY to_char(first_time, 'yyyy - mm - dd'),
              to_char(first_time, 'hh24') asc;