查看Oracle的redo日志切换频率

两个sql，原理是一样的，第二个用到了统计函数。
时间单位：分钟

select * from v$log
where a.THREAD# = 1
select b.SEQUENCE#, b.FIRST_TIME,
       a.SEQUENCE#, a.FIRST_TIME,
       round(((a.FIRST_TIME-b.FIRST_TIME)*24)*60,2)
from v$log_history a, v$log_history b
where a.SEQUENCE# = b.SEQUENCE#+1
and b.THREAD#=1
order by a.SEQUENCE# desc

select sequence#,first_time,nexttime,round(((first_time-nexttime)*24)*60,2) diff
from (
select sequence#,first_time, lag(first_time) over(order by sequence#) nexttime
from v$log_history
where thread#=1
) order by sequence# desc