--查询日志的切换频率

select  t1.RECID as srecid

       ,t2.RECID as erecid

       ,t1.FIRST_TIME as stime

       ,t2.FIRST_TIME as etime

       ,round((t2.FIRST_TIME-t1.FIRST_TIME)*1440,2) as minutes

from v$log_history t1,v$log_history t2

where t1.RECID+1=t2.RECID and /*选择时间段*/t1.FIRST_TIME between trunc(sysdate)/*起始*/ and sysdate/*终止*/

order by t1.RECID desc