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过v$sqlarea,v$sql查询最占用资源的查询

Posted on 2011-08-03 09:47 疯狂 阅读(329) 评论(0)  编辑  收藏 所属分类: databasejava性能
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。
 
V$SQL是内存共享SQL区域中已经解析的SQL语句。

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;

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