监控数据库性能的常用的SQL

　　
　　1. 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
　　group by event order by 4;
　　
　　2. 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;
　　
　　3. 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;
　　
　　4. 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#;
　　
　　5.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;
　　
　　6. 监控 SGA 的命中率
　　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;
　　
　　7. 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;
　　
　　8. 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;
　　
　　9. 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;
　　
　　10. 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');
　　
　　11. 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)');
　　
　　12. 监控当前数据库谁在运行什么SQL语句
　　SELECT osuser, username, sql_text from v$session a, v$sqltext b
　　where a.sql_address =b.address order by address, piece;
　　
　　13. 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
　　
　　14. 找ORACLE字符集
　　select * from sys.props$ where name='NLS_CHARACTERSET';
　　
　　15. 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';
　　select count(*) from v$dispatcher;
　　select servers_highwater from v$mts;
　　servers_highwater接近mts_max_servers时，参数需加大
　　
　　16. 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 * from ts_blocks_v;
　　select tablespace_name,sum(bytes),max(bytes),count(block_id) from dba_free_space
　　group by tablespace_name;
　　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);
　　
　　17. 表、索引的情况检查
　　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;
　　
　　18、找使用CPU多的用户session
　　12是cpu used by this session
　　select a.sid,spid,status,substr(a.program,1,10) 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;
　　

【责编:admin】

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