一、数据库方面
1. 调整 pga_aggregate_target 到50M （现在为24M）
2. db_cache_size 调整到 160M (现在为24M) 需重启数据库。
3. shared_pool_size 暂时不调整(现在为56M)
4. 调整sga_max_size 到310M（现在为170M）
脚本如下：（sysdba）
alter system set sga_max_size=310m scope=spfile;
shutdown immediate;
startup ;
alter system set db_cache_size=160m;
alter system set pga_aggregate_target=50m;
从V$SQLAREA中查询最占用资源的查询
select b.username username,a.disk_reads reads,
a.executions exec,a.disk_reads/decode(a.executions,0,1,a.executions) rds_exec_ratio,
a.sql_text Statement
from v$sqlarea a,dba_users b
where a.parsing_user_id=b.user_id
and a.disk_reads > 100000
order by a.disk_reads desc;
用buffer_gets列来替换disk_reads列可以得到占用最多内存的sql语句的相关信息。
列出使用频率最高的5个查询：
select sql_text,executions
from (select sql_text,executions,
rank() over
(order by executions desc) exec_rank
from v$sql)
where exec_rank <=5;
消耗磁盘读取最多的sql top5：
select disk_reads,sql_text
from (select sql_text,disk_reads,
dense_rank() over
(order by disk_reads desc) disk_reads_rank
from v$sql)
where disk_reads_rank <=5;
找出需要大量缓冲读取（逻辑读）操作的查询：
select buffer_gets,sql_text
from (select sql_text,buffer_gets,
dense_rank() over
(order by buffer_gets desc) buffer_gets_rank
from v$sql)
where buffer_gets_rank<=5;