查询Oracle正在执行和执行过的SQL语句
 
---正在执行的

select a.username, a.sid,b.SQL_TEXT, b.SQL_FULLTEXT
 from v$session a, v$sqlarea b
where a.sql_address = b.address

---执行过的
select b.SQL_TEXT,b.FIRST_LOAD_TIME,b.SQL_FULLTEXT
 from v$sqlarea b
where b.FIRST_LOAD_TIME between '2012-10-20/09:00:00' and
 '2009-10-21/09:00:00' order by b.FIRST_LOAD_TIME

其他
select OSUSER,PROGRAM,USERNAME,SCHEMANAME,B.Cpu_Time,STATUS,B.SQL_TEXT
from V$SESSION A LEFT JOIN V$SQL B ON A.SQL_ADDRESS=B.ADDRESS AND A.SQL_HASH_VALUE=B.HASH_VALUE order by b.cpu_time desc

select address, sql_text, piece
from v$session, v$sqltext
where address = sql_address
-- and machine = < you machine name >
order by address, piece

查找前十条性能差的sql.

SELECT * FROM (select PARSING_USER_ID,EXECUTIONS,SORTS,
COMMAND_TYPE,DISK_READS,sql_text FROM v$sqlarea
order BY disk_reads DESC )where ROWNUM<10 ;

查看占io较大的正在运行的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,si.physical_reads,
si.block_changes FROM v$session se,v$session_wait st,
v$sess_io si,v$process pr WHERE 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