oracle优化6

检查 buffer pool HIT_RATIO 执行
SELECT NAME , (PHYSICAL_READS/(DB_BLOCK_GETS+CONSISTENT_GETS)) "MISS_HIT_RATIO" FROM V$BUFFER_POOL_STATISTICS WHERE (DB_BLOCK_GETS+ CONSISTENT_GETS)> 0 ;
( 正常时 db buffer cache hit ratio 应该大于 90%, 正常时 buffer pool MISS_HIT_RATIO 应该小于 10%)

数据库回滚段性能检查 :
检查 Ratio 执行
SELECT SUM (WAITS)* 100 /SUM (GETS) "RATIO", SUM (WAITS) "WAITS", SUM (GETS) "GETS" FROM V$ROLLSTAT;

检查 count/value 执行 :
SELECT CLASS ,COUNT FROM V$WAITSTAT WHERE CLASS LIKE '%UNDO%' ;
SELECT VALUE FROM V$SYSSTAT WHERE NAME = 'CONSISTENT GETS' ;
( 两者的 value 值相除 )

检查 average_wait 执行 :
SELECT EVENT,TOTAL_WAITS,TIME_WAITED,AVERAGE_WAIT FROM V$SYSTEM_EVENT WHERE EVENT LIKE '%UNDO%' ;

检查 RBS header get ratio 执行 :
SELECT N.NAME ,S.USN,S.WRAPS, DECODE(S.WAITS, 0 , 1 , 1 - S.WAITS/S.GETS)"RBS HEADER GET RATIO" FROM V$ROLLSTAT S,V$ROLLNAME N WHERE S.USN=N.USN;
( 正常时 Ratio 应该小于 1%, count/value 应该小于 0.01%,average_wait 最好为 0 ，该值越小越好 ,RBS header get ratio 应该大于 95%)

杀会话的脚本 :
SELECT A.SID,B.SPID,A.SERIAL#,A.LOCKWAIT,A.USERNAME,A.OSUSER,A.LOGON_TIME,A.LAST_CALL_ET/ 3600 LAST_HOUR,A.STATUS, 'ORAKILL ' ||SID|| ' ' ||SPID HOST_COMMAND, 'ALTER SYSTEM KILL SESSION ''' ||A.SID|| ',' ||A.SERIAL#|| '''' SQL_COMMAND FROM V$SESSION A,V$PROCESS B WHERE A.PADDR=B.ADDR AND SID> 6 ;

查看排序段的性能 :
SQL >SELECT NAME , VALUE FROM V$SYSSTAT WHERE NAME IN ( 'SORTS (MEMORY)' , 'SORTS (DISK)' );

7 、查看数据库库对象 :
SELECT OWNER, OBJECT_TYPE, STATUS, COUNT (*) COUNT # FROM ALL_OBJECTS GROUP BY OWNER, OBJECT_TYPE, STATUS;

8 、查看数据库的版本 : 　
SELECT * FROM V$VERSION;

9 、查看数据库的创建日期和归档方式 :
SELECT CREATED, LOG_MODE, LOG_MODE FROM V$DATABASE;