最近在看一些Oracle分享的時候，經常提到導出ASH的dump給另外的人來做分析，但我沒有什麽相關的操作，不知道是怎樣的一個操作流程，於是上網看了各種博文。於是自己動手做實驗做一次導出導入。

實驗環境：Oracle 11.2.0.4+rhel 7.2

執行下面的語句對ASH信息做dump操作

[email protected]>alter system set events ‘immediate trace name ashdump level 10‘;

上面的語句中level的意思是dump出ASH buffer中最近n分鐘的數據，這裏以10分鐘為例。

使用下面的語句打到對應的trace文件

[email protected]>SELECT value FROM v$diag_info WHERE name = ‘Default Trace File‘;

VALUE
-------------------------------------------------------------------
/u01/app/oracle/diag/rdbms/ora11g/ora11g/trace/ora11g_ora_7556.trc

先簡單查看一下trace文件中的內容：

從上面的兩個圖中可以看到trace文件中包含了三類信息：trace的基本信息、導入dump的方法和ash的實際數據，其實只要按照trace中的文件給出的方法就可以很容易的把dump數據導入到數據庫中。

1、創建臨時表

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

2、生成sqlldr的control file

[[email protected] 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文件中的數據導入到臨時表中

[[email protected] ash]$ sqlldr zx/zx control=ashldr.ctl data=ora11g_ora_7556.trc errors=1000000

SQL*Loader: Release 11.2.0.4.0 - Production on Sat Sep 23 17:16:40 2017

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

Commit point reached - logical record count 19
Commit point reached - logical record count 37
Commit point reached - logical record count 55
Commit point reached - logical record count 73
Commit point reached - logical record count 91
Commit point reached - logical record count 109
Commit point reached - logical record count 127
Commit point reached - logical record count 145
Commit point reached - logical record count 163
Commit point reached - logical record count 181
Commit point reached - logical record count 199
Commit point reached - logical record count 217
Commit point reached - logical record count 235
Commit point reached - logical record count 253
Commit point reached - logical record count 271
Commit point reached - logical record count 289
Commit point reached - logical record count 307
Commit point reached - logical record count 325
Commit point reached - logical record count 343
Commit point reached - logical record count 361
Commit point reached - logical record count 379
Commit point reached - logical record count 397
Commit point reached - logical record count 415
Commit point reached - logical record count 433
Commit point reached - logical record count 451
Commit point reached - logical record count 469
Commit point reached - logical record count 487
Commit point reached - logical record count 505
Commit point reached - logical record count 523
Commit point reached - logical record count 541
Commit point reached - logical record count 559
Commit point reached - logical record count 577
Commit point reached - logical record count 595
Commit point reached - logical record count 613
Commit point reached - logical record count 631
Commit point reached - logical record count 649
Commit point reached - logical record count 651


[email protected]>select count(*) from ashdump;

  COUNT(*)
----------
       650

數據導入成功後就可以根據具體的問題現在做近一步的分析。

其實導出和導入的步驟非常簡單，Oracle直接給出了步驟，難的是拿到數據後如何使用這些數據進行近一步的分析，從而找出問題的根本原因。

如下分析每個sampletime的會話數量

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

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

本文出自 “DBA Fighting!” 博客，請務必保留此出處http://hbxztc.blog.51cto.com/1587495/1968021

Oracle 導出 ASH的dump信息