1.  --查看表锁  

SELECT * FROM SYS.V_$SQLAREA WHERE DISK_READS > 100;  

2.  --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  

GROUPBY EVENT  

ORDERBY 4;  

3.  --回滚段的争用情况

SELECTNAME, WAITS, GETS, WAITS / GETS "Ratio"

FROM V$ROLLSTAT A, V$ROLLNAME B  

WHERE A.USN = B.USN;  

4.  --查看前台正在发出的SQL语句

SELECT USER_NAME, SQL_TEXT 　　  

FROM V$OPEN_CURSOR 　　  

WHERE SID IN (SELECT SID  

FROM (SELECT SID, SERIAL#, USERNAME, PROGRAM 　　  

FROM V$SESSION 　　  

WHERE STATUS = ‘ACTIVE‘));  

5.  --数据表占用空间大小情况

SELECT SEGMENT_NAME, TABLESPACE_NAME, BYTES, BLOCKS  

FROM USER_SEGMENTS  

WHERE SEGMENT_TYPE = ‘TABLE‘

ORDERBY BYTES DESC, BLOCKS DESC;  

6.  --查看表空间碎片大小

SELECT TABLESPACE_NAME,  

      ROUND(SQRT(MAX(BLOCKS) / SUM(BLOCKS)) *  

            (100 / SQRT(SQRT(COUNT(BLOCKS)))),  

            2) FSFI  

FROM DBA_FREE_SPACE  

GROUPBY TABLESPACE_NAME  

ORDERBY 1;  

7.  --查看表空间占用磁盘情况

SELECT B.FILE_ID 文件ID号,  

      B.TABLESPACE_NAME 表空间名,  

      B.BYTES 字节数,  

      (B.BYTES - SUM(NVL(A.BYTES, 0))) 已使用,  

SUM(NVL(A.BYTES, 0)) 剩余空间,  

SUM(NVL(A.BYTES, 0)) / (B.BYTES) * 100 剩余百分比  

FROM DBA_FREE_SPACE A, DBA_DATA_FILES B  

WHERE A.FILE_ID = B.FILE_ID  

GROUPBY B.TABLESPACE_NAME, B.FILE_ID, B.BYTES  

ORDERBY B.FILE_ID;  

8.  --查看session使用回滚段

SELECT R.NAME 回滚段名,  

      S.SID,  

      S.SERIAL#,  

      S.USERNAME 用户名,  

      T.STATUS,  

      T.CR_GET,  

      T.PHY_IO,  

      T.USED_UBLK,  

      T.NOUNDO,  

      SUBSTR(S.PROGRAM, 1, 78) 操作程序  

FROM SYS.V_$SESSION S, SYS.V_$TRANSACTION T, SYS.V_$ROLLNAME R  

WHERE T.ADDR = S.TADDR  

AND T.XIDUSN = R.USN  

ORDERBY T.CR_GET, T.PHY_IO;  

9.  --查看SGA区剩余可用内存

SELECTNAME,  

      　　　　　　SGASIZE / 1024 / 1024　　　　　　　　"Allocated(M)",  

      　　　　　　BYTES / 1024　　　　　　　　　　　 "**空间(K)",  

      　　　　　　ROUND(BYTES / SGASIZE * 100, 2) 　　　"**空间百分比(%)"

FROM (SELECTSUM(BYTES) SGASIZE FROM SYS.V_$SGASTAT) S,  

      SYS.V_$SGASTAT F 　　  

WHERE F.NAME = ‘free memory‘;  

10.  --监控表空间I/O比例

SELECT DF.TABLESPACE_NAME NAME,  

      DF.FILE_NAME       "file",  

      F.PHYRDS           PYR,  

      F.PHYBLKRD         PBR,  

      F.PHYWRTS          PYW,  

      F.PHYBLKWRT        PBW  

FROM V$FILESTAT F, DBA_DATA_FILES DF  

WHERE F.FILE# = DF.FILE_ID  

ORDERBY DF.TABLESPACE_NAME;  

11.  --监控SGA命中率

SELECT A.VALUE + B.VALUE "logical_reads",  

      C.VALUE "phys_reads",  

      ROUND(100 * ((A.VALUE + B.VALUE) - C.VALUE) / (A.VALUE + B.VALUE)) "BUFFER HIT RATIO"

FROM V$SYSSTAT A, V$SYSSTAT B, V$SYSSTAT C  

WHERE A.STATISTIC# = 38  

AND B.STATISTIC# = 39  

AND C.STATISTIC# = 40;  

12.  --监控 SGA 中字典缓冲区的命中率

SELECT PARAMETER,  

      GETS,  

      GETMISSES,  

      GETMISSES / (GETS + GETMISSES) * 100 "miss ratio",  

      (1 - (SUM(GETMISSES) / (SUM(GETS) + SUM(GETMISSES)))) * 100 "Hit ratio"

FROM V$ROWCACHE  

WHERE GETS + GETMISSES <> 0  

GROUPBY PARAMETER, GETS, GETMISSES;  

13.  --监控 SGA **享缓存区的命中率，应该小于1%

SELECTSUM(PINS) "Total Pins",  

SUM(RELOADS) "Total Reloads",  

SUM(RELOADS) / SUM(PINS) * 100 LIBCACHE  

FROM V$LIBRARYCACHE;  

14.  --监控 SGA 中重做日志缓存区的命中率，应该小于1%

SELECTNAME,  

      GETS,  

      MISSES,  

      IMMEDIATE_GETS,  

      IMMEDIATE_MISSES,  

      DECODE(GETS, 0, 0, MISSES / GETS * 100) RATIO1,  

      DECODE(IMMEDIATE_GETS + IMMEDIATE_MISSES,  

             0,  

             0,  

             IMMEDIATE_MISSES / (IMMEDIATE_GETS + IMMEDIATE_MISSES) * 100) RATIO2  

FROM V$LATCH  

WHERENAMEIN (‘redo allocation‘, ‘redo copy‘);  

15.  --监控内存和硬盘的排序比率，最好使它小于 .10

SELECTNAME, VALUE  

FROM V$SYSSTAT  

WHERENAMEIN (‘sorts (memory)‘, ‘sorts (disk)‘);  

16.  --监控字典缓冲区

SELECTSUM(GETS) "DICTIONARY GETS",  

SUM(GETMISSES) "DICTIONARY CACHE GET MISSES"

FROM V$ROWCACHE;  

17.  --非系统用户建在SYSTEM表空间中的表

SELECT OWNER, TABLE_NAME  

FROM DBA_TABLES  

WHERE TABLESPACE_NAME IN (‘SYSTEM‘, ‘USER_DATA‘)  

AND OWNER NOTIN

      (‘SYSTEM‘, ‘SYS‘, ‘OUTLN‘, ‘ORDSYS‘, ‘MDSYS‘, ‘SCOTT‘, ‘HOSTEAC‘);  

18.  --性能最差的SQL

SELECT *  

FROM (SELECT PARSING_USER_ID EXECUTIONS,  

              SORTS,  

              COMMAND_TYPE,  

              DISK_READS,  

              SQL_TEXT  

FROM V$SQLAREA  

ORDERBY DISK_READS DESC)  

WHERE ROWNUM < 100;  

--用下列SQL 工具找出低效SQL ：  

SELECT EXECUTIONS,  

      DISK_READS,  

      BUFFER_GETS,  

      ROUND((BUFFER_GETS - DISK_READS) / BUFFER_GETS, 2) HIT_RADIO,  

      ROUND(DISK_READS / EXECUTIONS, 2) READS_PER_RUN,  

      SQL_TEXT  

FROM V$SQLAREA  

WHERE EXECUTIONS > 0  

AND BUFFER_GETS > 0  

AND (BUFFER_GETS - DISK_READS) / BUFFER_GETS < 0.8  

ORDERBY 4 DESC;  

19.  --读磁盘数超100次的sql

SELECT * FROM SYS.V_$SQLAREA WHERE DISK_READS > 100;  

20.  --最频繁执行的sql

SELECT * FROM SYS.V_$SQLAREA WHERE EXECUTIONS > 100;  

21.  --查询使用CPU多的用户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  

ORDERBY VALUE DESC;  

22.  --当前每个会话使用的对象数

SELECT A.SID, S.TERMINAL, S.PROGRAM, COUNT(A.SID)  

FROM V$ACCESS A, V$SESSION S  

WHERE A.OWNER <> ‘SYS‘

AND S.SID = A.SID  

GROUPBY A.SID, S.TERMINAL, S.PROGRAM  

ORDERBYCOUNT(A.SID);