Oracle监控语句

1.监控事例的等待
	select event,sum(decode(wait_Time,0,0,1)) "rev",
		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 wner='&owner'
	group by segment_name;



18、找使用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 order by value desc;



	监控数据库状态的目的就是找到相关的瓶颈点，但也许有时你的监控语句就会是你的瓶颈点，包括您后台的一些自动的监控。
Jason就遇到这样的囧事，不是dbconsole占资源（响应时间>2s）就是监控lock语句占资源,包括oracle的某些maintain功能，
需要很好的时间schedual。