使用Oracle10g的Flashback Query进行数据闪回-技术开发专区

使用Oracle10g的Flashback Query进行数据闪回

作者：eygle 编辑：阿雪 2007-05-09 17:59

【IT168技术文档】

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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