—————【1性能监控】————— 

      --1. 检测数据库中的事件和等待 

       SELECT event, total_waits, total_timeouts,time_waited, average_wait

       FROM v$system_event

      --2. 查询会话中的事件和等待时间 

      SELECT sid, event, total_waits,average_wait

      FROM v$session_event ;

       --3. 查询等待进程 

       SELECT sid, seq#, event, wait_time, state

       FROM v$session_wait;

       --4. 监控全局区的性能 

       SELECT * from v$sgastat;

       --5. 查询命中率 

       SELECT gethitratio

       FROM v$librarycache

       WHERE namespace = 'SQL AREA';

       --6. 当前 sql 语句 

       SELECT sql_text, users_executing,executions, loads

       FROM v$sqlarea;

        --7. 查询高速缓存中的命中率 
        SELECT sum(pins) "Executions", sum(reloads) "Cache Misses",sum(reloads)/sum(pins)

       FROM v$librarycache;

       --8. 查询全局字典中的有效装载次数 

       SELECT namespace,pins,reloads,invalidations

       FROM v$librarycache;

       --9. 回滚段的争用情况 

       SELECT name, waits, gets, waits/gets "Ratio"

       FROM v$rollstat a, v$rollname b

       WHERE a.usn = b.usn;

       --10. 监控表空间的 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

       ORDER BY  df.tablespace_name;

       --11. 监控文件系统的 I/O 比例 

       SELECT substr(a.file#,1,2) "#", substr(a.name,1,30) "Name",a.status, a.bytes, b.phyrds, b.phywrts

       FROM v$datafile a, v$filestat b

       WHERE  a.file# = b.file#;

       --12. 在某个用户下找所有的索引 

       SELECT user_indexes.table_name, user_indexes.index_name,uniqueness, column_name

       FROM user_ind_columns, user_indexes

       WHERE user_ind_columns.index_name = user_indexes.index_name

       AND user_ind_columns.table_name = user_indexes.table_name

       ORDER BY  user_indexes.table_type, user_indexes.table_name,user_indexes.index_name, column_position;

       --13. 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

       GROUP BY parameter, gets, getmisses;

       --14. 监控 SGA 中共享缓存区的命中率，应该小于 1% 

       SELECT sum(pins) "Total Pins", sum(reloads) "Total Reloads",sum(reloads)/sum(pins) *100 libcache

       FROM v$librarycache;

       SELECT sum(pinhits-reloads)/sum(pins) "hit radio",sum(reloads)/sum(pins) "reload percent"

       FROM v$librarycache;

       --15. 显示所有数据库对象的类别和大小 

       SELECT count(name) num_instances ,type ,sum(source_size) source_size ,sum(parsed_size) parsed_size ,

       sum(code_size) code_size,sum(error_size) error_size,sum(source_size) +sum(parsed_size) +sum(code_size) +

       sum(error_size) size_required

       FROM dba_object_size

       GROUP BY type 

       ORDER BY  2;

       --16. 监控 SGA 中重做日志缓存区的命中率，应该小于 1% 

       SELECT name, 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 

       WHERE name IN ('redo allocation', 'redo copy');

       --17. 监控内存和硬盘的排序比率，最好使它小于 .10 ，增加 sort_area_size 

       SELECT name, value 

       FROM v$sysstat 

       WHERE name IN ('sorts (memory)', 'sorts (disk)');

       --18. 监控字典缓冲区 

       SELECT (sum(pins - reloads)) / sum(pins) "lib cache" 

       FROM v$librarycache;

        SELECT (sum(gets - getmisses - usage - fixed)) / sum(gets) "row cache"

        FROM  v$rowcache;

        SELECT sum(pins) "executions", sum(reloads) "cache misses while executing" 

        FROM v$librarycache;

        --后者除以前者 , 此比率小于 1%, 接近 0% 为好

        SELECT sum(gets) "dictionary gets",sum(getmisses) "dictionary cache get misses"

        FROM v$rowcache;

       --19. 找 ORACLE 字符集 

       SELECT * FROM sys.props$ 

       WHERE name='NLS_CHARACTERSET';

       --20. 监控 MTS 

       SELECT busy/(busy+idle) "shared servers busy" 

       FROM v$dispatcher;

       --此值大于 0.5 时，参数需加大

       SELECT  sum(wait)/sum(totalq) "dispatcher waits" 

       FROM  v$queue where type='dispatcher';

       --21. 碎片程度 

       SELECT tablespace_name,count(tablespace_name) 

       FROM dba_free_space group by tablespace_name

       HAVING count(tablespace_name)>10;

       ALTER tablespace name coalesce;

       ALTER table name deallocate unused;

        CREATE or REPLACE view ts_blocks_v as

        SELECT tablespace_name,block_id,bytes,blocks,'free space' segment_name FROM dba_free_space

        UNION ALL

        SELECT  tablespace_name,block_id,bytes,blocks,segment_name FROM dba_extents;

        SELECT tablespace_name,sum(bytes),max(bytes),count(block_id) 

        FROM dba_free_space

        GROUP BY tablespace_name;

        --22.查看碎片程度高的表

        SELECT segment_name table_name , COUNT(*) extents

        FROM dba_segments WHERE owner NOT IN ('SYS', 'SYSTEM') GROUP BY segment_name

        HAVING COUNT(*) = (SELECT MAX( COUNT(*) ) FROM dba_segments GROUP BY segment_name);

       --23. 表、索引的存储情况检查

        SELECT segment_name,sum(bytes),count(*) ext_quan 

        FROM dba_extents 

        WHERE  tablespace_name='&tablespace_name' and segment_type='TABLE' 

        GROUP BY  tablespace_name,segment_name;

        SELECT segment_name,count(*) 

        FROM dba_extents 

        WHERE segment_type='INDEX' and owner='&owner'

        GROUP  BY  segment_name;

        --24.找使用 CPU 多的用户 session

        -- 12 是 cpu used by this 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;