在网上随意浏览，发现一个针对数据库表的操作进行压力测试的方案，看到跟帖比较多，大家反应比较积极，都认为采用SQL语句进行检测，是一个很好的思路，特此记录。

      问题：

      测试工程师正在测试一个应用的压力测试，会操作oracle数据库上的一张表，问下，如何在数据库层次上监控这张表，检测压力测试对数据库以及这张表的影响，看是否会出问题？

      回答：

     SQL code 

监控数据库性能的SQL 
查看tablespace的空間使用情況
select tablespace_name,sum(bytes)/1024/1024 from dba_free_space group by tablespace_name
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;