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下面是一些监控数据库性能的SQL语句，希望对大家有帮助： 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　 type,　　count(name) num_instances,　　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 1;

　 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,　　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 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,1,40) 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;