Oracle数据库系统负载过高影响应用-处理思路

1：使用vmstat和top查看系统cpu，io，内存使用情况
2：查看当前状态下存在的等待事件
select sid,event,p1,p2,seconds_in_wait from v$session_wait where event not like '%SQL%' and event not like 'rdbms%' and event not like '%message%' and event not like '%Streams AQ%' AND EVENT NOT LIKE '%slave%' order by event;
3：检查出现问题的语句
SQL> @sql_sid
Enter value for sid: 
old 1: 
select sql_text from v$sqltext where hash_value in(select decode(sql_hash_value,0,prev_hash_value,sql_hash_value) from v$session where sid='&sid') order by piece;
new 1: select sql_text from v$sqltext where hash_value in(select decode(sql_hash_value,0,prev_hash_value,sql_hash_value) from v$session where sid=’ ′) order by piece;

4： 检查问题语句的执行计划，查看执行计划是否正确
set autotrace traceonly
set autotrace on
5：如果执行计划不对：
（1）：

分析表

exec dbms_stats.gather_table_stats(ownname => 'scott',tabname => 'work_list',estimate_percent => 10,method_opt=> 'for all indexed columns') ; 

（2）：分析想相关索引

。。。后续接着