通过v$sqlarea,v$sql查询最占用资源的查询 ORACLE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;

另外可以通过awrrpt (性能报表）生成html文档来查看数据库运行状况