Oracle負荷超過的核查

1.查找當前表級鎖的SQL如下：

select sess.sid,
    sess.serial#,
    lo.oracle_username,
    lo.os_user_name,
    ao.object_name,
    lo.locked_mode
    from v$locked_object lo,
    dba_objects ao,
    v$session sess
where ao.object_id = lo.object_id and lo.session_id = sess.sid;

 
2.監控當前數據庫誰在運行什麼SQL語句

select osuser, username, sql_text
from  v$session a, v$sqltext b
where  a.sql_address =b.address order by address, piece;

 
3.找使用CPU多的用戶session

select a.sid,spid,status,substr(a.program,1,40) prog, a.terminal,osuser,value/60/100 value
from  v$session a,v$process b,v$sesstat c
where  c.statistic#=12 and
       c.sid=a.sid and
       a.paddr=b.addr
       order by value desc;

 
4.等待最多的SQL

SELECT   a.program, a.session_id, a.user_id, d.username, s.sql_text,
         SUM (a.wait_time + a.time_waited) total_wait_time
    FROM v$active_session_history a, v$sqlarea s, dba_users d
   WHERE a.sample_time BETWEEN SYSDATE - 30 / 2880 AND SYSDATE
     AND a.sql_id = s.sql_id
     AND a.user_id = d.user_id
GROUP BY a.program, a.session_id, a.user_id, s.sql_text, d.username;

5.查看消耗資源最多的SQL

SELECT hash_value, executions, buffer_gets, disk_reads, parse_calls
FROM V$SQLAREA
WHERE buffer_gets > 10000000 OR disk_reads > 1000000
ORDER BY buffer_gets + 100 * disk_reads DESC;