--查询当前执行IO最多的sql，并按大到小来排序
select cast(buffer_gets/decode(EXECUTions,0,10000,EXECUTions) as int) 平均IO ,
EXECUTions 执行次数,buffer_gets 总逻辑IO,disk_reads 硬盘读取,
sql_text SQl语句 from v$sqlarea
where parsing_schema_name='HQT'
order by buffer_gets desc
oracle查看执行计划
你可以在session中set autotrace on,你可以看到统计信息和执行计划
也可以使用dbms_xplan包去查看执行计划。
Oracle IO优化心得
http://wenku.baidu.com/link?url=JsMtHdp5NLN2IqZf06Bbldhcc6tKIqGBf7XhbTwo5o7YV0QkKBgUTtGGGoZhc8j0e4rlJ56eIKtd3GIOIBuKsOdbebfHx9UUu6A7C7J0NbO
查看IO较大正在运行的session:
SELECT se.sid, se.serial#, pr.SPID, se.username, se.status, se.terminal, se.program, se.MODULE, se.sql_address, st.event, st.p1text, st.p1, st.p2, st.p3, st.STATE, st.SECONDS_IN_WAIT, si.physical_reads, si.block_changes FROM v$session se, v$session_wait st, v$sess_io si, v$process prWHERE st.sid=se.sid AND st.sid=si.sid AND se.PADDR=pr.ADDR AND se.sid>6 AND st.wait_time=0 AND st.event NOT LIKE '%SQL%'ORDER BY physical_reads DESC