使用Oracle10g的Flashback Query进行数据闪回

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作者：eygle | 【转载时请以超链接形式标明文章出处和作者信息及本声明】
链接：http://www.eygle.com/archives/2005/03/eoaoracle10gaef.html

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Oracle10g对于闪回查询进行了增强，支持更简单的SQL操作，允许对误删除、误更新等DML操作进行闪回。
看一下以下测试:
1.原表记录



$ sqlplus eygle/eygle

SQL*Plus: Release 10.1.0.2.0 - Production on Wed Mar 30 08:52:04 2005

Copyright (c) 1982, 2004, Oracle.  All rights reserved.


Connected to:
Oracle Database 10g Enterprise Edition Release 10.1.0.2.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options

EYGLE  on 30-MAR-05 >select count(*) from t1;

  COUNT(*)
----------
      9318

2.误删除所有记录
并且提交更改。



EYGLE  on 30-MAR-05 >delete from t1;

9318 rows deleted.

EYGLE  on 30-MAR-05 >commit;

Commit complete.

EYGLE  on 30-MAR-05 >select count(*) from t1;

  COUNT(*)
----------
         0

3.获得当前SCN
如果能够确切知道删除之前SCN最好，如果不知道，可以进行闪回查询尝试.



EYGLE  on 30-MAR-05 >select dbms_flashback.get_system_change_number from dual;

GET_SYSTEM_CHANGE_NUMBER
------------------------
                10671006

EYGLE  on 30-MAR-05 >select count(*) from t1 as of scn 10671000;

  COUNT(*)
----------
         0

EYGLE  on 30-MAR-05 >select count(*) from t1 as of scn 10670000;

  COUNT(*)
----------
      9318

我们看到在SCN=10670000时，数据都在。
4.恢复数据.



EYGLE  on 30-MAR-05 >insert into t1 select * from t1 as of scn 10670000;

9318 rows created.

EYGLE  on 30-MAR-05 >commit;

Commit complete.

EYGLE  on 30-MAR-05 >select count(*) from t1;

  COUNT(*)
----------
      9318

EYGLE  on 30-MAR-05 >

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