Oracle 导出 ASH的dump信息

最近在看一些Oracle分享的时候，经常提到导出ASH的dump给另外的人来做分析，但我没有什么相关的操作，不知道是怎样的一个操作流程，于是上网看了各种博文。于是自己动手做实验做一次导出导入。

实验环境：Oracle 11.2.0.4+rhel 7.2

执行下面的语句对ASH信息做dump操作

sys@ORA11G>alter system set events 'immediate trace name ashdump level 10';

上面的语句中level的意思是dump出ASH buffer中最近n分钟的数据，这里以10分钟为例。

使用下面的语句打到对应的trace文件

sys@ORA11G>SELECT value FROM v$diag_info WHERE name = 'Default Trace File';VALUE-------------------------------------------------------------------/u01/app/oracle/diag/rdbms/ora11g/ora11g/trace/ora11g_ora_7556.trc

先简单查看一下trace文件中的内容：

从上面的两个图中可以看到trace文件中包含了三类信息：trace的基本信息、导入dump的方法和ash的实际数据，其实只要按照trace中的文件给出的方法就可以很容易的把dump数据导入到数据库中。

1、创建临时表

CREATE TABLE ashdump ASSELECT * FROM SYS.WRH$_ACTIVE_SESSION_HISTORY WHERE rownum < 0；

2、生成sqlldr的control file

[oracle@rhel7 ash]$ sed -n '1,/^Step 2:/d;/^Step 3:/,$d;p' ora11g_ora_7556.trc |sed '/^-/d' > ashldr.ctl

3、使用sqlldr工具把trace文件中的数据导入到临时表中

[oracle@rhel7 ash]$ sqlldr zx/zx control=ashldr.ctl data=ora11g_ora_7556.trc errors=1000000SQL*Loader: Release 11.2.0.4.0 - Production on Sat Sep 23 17:16:40 2017Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.Commit point reached - logical record count 19Commit point reached - logical record count 37Commit point reached - logical record count 55Commit point reached - logical record count 73Commit point reached - logical record count 91Commit point reached - logical record count 109Commit point reached - logical record count 127Commit point reached - logical record count 145Commit point reached - logical record count 163Commit point reached - logical record count 181Commit point reached - logical record count 199Commit point reached - logical record count 217Commit point reached - logical record count 235Commit point reached - logical record count 253Commit point reached - logical record count 271Commit point reached - logical record count 289Commit point reached - logical record count 307Commit point reached - logical record count 325Commit point reached - logical record count 343Commit point reached - logical record count 361Commit point reached - logical record count 379Commit point reached - logical record count 397Commit point reached - logical record count 415Commit point reached - logical record count 433Commit point reached - logical record count 451Commit point reached - logical record count 469Commit point reached - logical record count 487Commit point reached - logical record count 505Commit point reached - logical record count 523Commit point reached - logical record count 541Commit point reached - logical record count 559Commit point reached - logical record count 577Commit point reached - logical record count 595Commit point reached - logical record count 613Commit point reached - logical record count 631Commit point reached - logical record count 649Commit point reached - logical record count 651zx@ORA11G>select count(*) from ashdump;  COUNT(*)----------       650

数据导入成功后就可以根据具体的问题现在做近一步的分析。

其实导出和导入的步骤非常简单，Oracle直接给出了步骤，难的是拿到数据后如何使用这些数据进行近一步的分析，从而找出问题的根本原因。

如下分析每个sampletime的会话数量

参考：http://www.eygle.com/archives/2009/08/howto_dump_ashinfo.html

https://antognini.ch/2017/07/offline-analysis-of-ash-data-with-ashdump/