如何利用Flashback Query 恢复误删除的数据

mac2022-06-30  18

网上有很多关于数据回复的文章,这里整理一篇供大家参考,希望能帮助的大家!

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好了,言归正传!如果你在工作中误删除了一部分重要的数据,并且已经提交,如果你需要回复这些数据,你可以登陆到数据库上仔细查看,是Oracle9iR2的话,你可以首先尝试使用flashback query闪回数据。

 

◆第一步:确认数据库的SCN变化:

 

SQL> col fscn for 9999999999999999999SQL> col nscn for 9999999999999999999SQL> select name,FIRST_CHANGE# fscn,NEXT_CHANGE# nscn,FIRST_TIME from v$archived_log;...................NAME                               FSCN       NSCN FIRST_TIME----------------------------     ---------   -------------------/mwarch/oracle/1_52413.dbf     12929941968   12929942881 2005-06-22 14:38:28/mwarch/oracle/1_52414.dbf     12929942881   12929943706 2005-06-22 14:38:32/mwarch/oracle/1_52415.dbf     12929943706   12929944623 2005-06-22 14:38:35/mwarch/oracle/1_52416.dbf     12929944623   12929945392 2005-06-22 14:38:38/mwarch/oracle/1_52417.dbf     12929945392   12929945888 2005-06-22 14:38:41/mwarch/oracle/1_52418.dbf     12929945888   12929945965 2005-06-22 14:38:44/mwarch/oracle/1_52419.dbf     12929945965   12929948945 2005-06-22 14:38:45/mwarch/oracle/1_52420.dbf     12929948945   12929949904 2005-06-22 14:46:05/mwarch/oracle/1_52421.dbf     12929949904   12929950854 2005-06-22 14:46:08/mwarch/oracle/1_52422.dbf     12929950854   12929951751 2005-06-22 14:46:11/mwarch/oracle/1_52423.dbf     12929951751   12929952587 2005-06-22 14:46:14.................../mwarch/oracle/1_52498.dbf     12930138975   12930139212 2005-06-22 15:55:57/mwarch/oracle/1_52499.dbf     12930139212   12930139446 2005-06-22 15:55:59/mwarch/oracle/1_52500.dbf     12930139446   12930139682 2005-06-22 15:56:00NAME                             FSCN           NSCN FIRST_TIME-------------------------  -------------       -----------/mwarch/oracle/1_52501.dbf     12930139682    12930139915 2005-06-22 15:56:02/mwarch/oracle/1_52502.dbf     12930139915    12930140149 2005-06-22 15:56:03/mwarch/oracle/1_52503.dbf     12930140149    12930140379 2005-06-22 15:56:05/mwarch/oracle/1_52504.dbf     12930140379    12930140610 2005-06-22 15:56:05/mwarch/oracle/1_52505.dbf     12930140610    12930140845 2005-06-22 15:56:0714811 rows selected.

 

◆此时的SCN为:

SQL> select dbms_flashback.get_system_change_number fscn from dual;                 FSCN--------------------         12930142214

◆此时使用应用用户尝试闪回

 

SQL> connect username/passwordConnected.

 

◆现有的数据

SQL> select count(*) from hs_passport;   COUNT(*)----------    851998

 

◆创建恢复表

SQL> create table hs_passport_recov as select * from hs_passport where 1=0;Table created.

 

◆此处选择SCN向前恢复

 以下为引用的内容:SQL> select count(*) from hs_passport as of scn 12929970422;  COUNT(*)----------    861686

 

◆尝试多个SCN,获取最佳值(注释:如果可以得知具体时间,那样则可以获得准确的数据闪回)

 以下为引用的内容:SQL> select count(*) from hs_passport as of scn &scn;Enter value for scn: 12929941968old   1: select count(*) from hs_passport as of scn &scnnew   1: select count(*) from hs_passport as of scn 12929941968  COUNT(*)----------    861684SQL> /Enter value for scn: 12927633776old   1: select count(*) from hs_passport as of scn &scnnew   1: select count(*) from hs_passport as of scn 12927633776select count(*) from hs_passport as of scn 12927633776                    *ERROR at line 1:ORA-01466: unable to read data - table definition has changedSQL> /Enter value for scn: 12929928784old   1: select count(*) from hs_passport as of scn &scnnew   1: select count(*) from hs_passport as of scn 12929928784  COUNT(*)----------    825110SQL> /Enter value for scn: 12928000000old   1: select count(*) from hs_passport as of scn &scnnew   1: select count(*) from hs_passport as of scn 12928000000select count(*) from hs_passport as of scn 12928000000                     *ERROR at line 1:ORA-01466: unable to read data - table definition has changed

 

 

◆注意:最后选择恢复到SCN为12929941968的时间点

 以下为引用的内容:SQL> insert into hs_passport_recov select * from hs_passport as of scn 12929941968;861684 rows created.SQL> commit;Commit complete.

 

注释:至此,则可以满足需要,找回误删除的部分数据,闪回恢复成功。

转载于:https://www.cnblogs.com/Siege-lion/p/5780696.html

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