Oracle性能相关的常用脚本介绍

在缺乏的可视化工具来监控数据库性能的情形下，常用的脚本就派上用场了，下面提供几个关于Oracle性能相关的脚本供大家参考。以下脚本均在Oracle 10g测试通过，Oracle 11g可能要做相应调整。

1、寻找最多BUFFER_GETS开销的SQL语句

--filename: top_sql_by_buffer_gets.sql
--Identify heavy SQL (Get the SQL with heavy BUFFER_GETS)
SET LINESIZE 190
COL sql_text FORMAT a100 WRAP
SET PAGESIZE 100

SELECT *
  FROM (  SELECT sql_text,
                 sql_id,
                 executions,
                 disk_reads,
                 buffer_gets
            FROM v$sqlarea
           WHERE DECODE (executions, 0, buffer_gets, buffer_gets / executions) >
                    (SELECT AVG (DECODE (executions, 0, buffer_gets, buffer_gets / executions))
                            + STDDEV (DECODE (executions, 0, buffer_gets, buffer_gets / executions))
                       FROM v$sqlarea)
                 AND parsing_user_id != 3D
        ORDER BY 4 DESC) x
 WHERE ROWNUM <= 10;

2、寻找最多DISK_READS开销的SQL语句

--filename:top_sql_disk_reads.sql
--Identify heavy SQL (Get the SQL with heavy DISK_READS)
SET LINESIZE 190
COL sql_text FORMAT a100 WRAP
SET PAGESIZE 100

SELECT *
  FROM (  SELECT sql_text,
                 sql_id,
                 executions,
                 disk_reads,
                 buffer_gets
            FROM v$sqlarea
           WHERE DECODE (executions, 0, disk_reads, disk_reads / executions) >
                    (SELECT AVG (DECODE (executions, 0, disk_reads, disk_reads / executions))
                            + STDDEV (DECODE (executions, 0, disk_reads, disk_reads / executions))
                       FROM v$sqlarea)
                 AND parsing_user_id != 3D
        ORDER BY 3 DESC) x
 WHERE ROWNUM <= 10

3、寻找最近30分钟导致资源过高开销的事件

--filename:top_event_in_30_min.sql
--Last 30 minutes result those resources that are in high demand on your system.
SET LINESIZE 180
COL event FORMAT a60
COL total_wait_time FORMAT 999999999999999999

  SELECT active_session_history.event,
         SUM (
            active_session_history.wait_time
            + active_session_history.time_waited)
            total_wait_time
    FROM v$active_session_history active_session_history
   WHERE active_session_history.sample_time BETWEEN SYSDATE - 60 / 2880
                                                AND SYSDATE
         AND active_session_history.event IS NOT NULL
GROUP BY active_session_history.event
ORDER BY 2 DESC;