oracle性能检测sql语句

　　1. 监控事例的等待　　select event,sum(decode(wait_Time,0,0,1)) "Prev",　　sum(decode(wait_Time,0,1,0)) "Curr",count(*) "Tot"　　from v$session_Wait　　group by event order by 4;　　2. 回滚段的争用情况　　select