利用BBED恢复UPDATE修改前的值
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2022-06-17 12:33:55
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实验过程如下: 1、创建表guo_test1 gyj@PROD create table guoyJoe_t1(id int,name varchar2(10));Table created.gyj@PROD insert into guoyJoe_t1 values(1,guoyJoe);1 row created.gyj@PROD insert into guoyJoe_t1 values(1,tom);1 row created.gyj@PROD
实验过程如下:
1、创建表guo_test1
gyj@PROD> create table guoyJoe_t1(id int,name varchar2(10)); Table created. gyj@PROD> insert into guoyJoe_t1 values(1,'guoyJoe'); 1 row created. gyj@PROD> insert into guoyJoe_t1 values(1,'tom'); 1 row created. gyj@PROD> COMMIT; Commit complete.
gyj@PROD> select name,dbms_rowid.rowid_relative_fno(rowid) file#,dbms_rowid.rowid_block_number(rowid) block#,dbms_rowid.rowid_row_number(rowid) row# from guoyJoe_t1; NAME FILE# BLOCK# ROW# ---------- ---------- ---------- ---------- guoyJoe 5 20877 0 tom 5 20877 1
3、刷数据缓存
gyj@PROD> alter system flush buffer_cache; System altered.
4、利用BBED找到这行记录(修改前的值:guoyJoe)
BBED> BBED> set file 5 block 20877 FILE# 5 BLOCK# 20877
5、发生UPDATE语句,把原来的值guoyJoe修改成oracledba
gyj@PROD> update guoyJoe_t1 set name='oracledba' where name='guoyJoe'; 1 row updated. gyj@PROD> commit; Commit complete
6、刷数据缓存
gyj@PROD> alter system flush buffer_cache; System altered.
7、利用BBED找到这行被修改后的记录(修改后的值上:oracledba)
BBED> set file 5 block 20877 FILE# 5 BLOCK# 20877
8、对比修改前与修改后的数据
BBED> d /v offset 8174 count 16 File: /u01/app/oracle/oradata/PROD/tp01.dbf (5) Block: 20877 Offsets: 8174 to 8189 Dba:0x0140518d ------------------------------------------------------- 2c000202 c1020767 756f794a 6f650106 l ,...á..guoyJoe.. BBED> d /v offset 8148 count 16 File: /u01/app/oracle/oradata/PROD/tp01.dbf (5) Block: 20877 Offsets: 8148 to 8163 Dba:0x0140518d ------------------------------------------------------- 2c010202 c102096f 7261636c 65646261 l ,...á..oracledba
9、开始恢复
10、恢复成功(oracledba--->guoyJoe)
gyj@PROD> alter system flush buffer_cache; System altered. gyj@PROD> select name,dbms_rowid.rowid_relative_fno(rowid) file#,dbms_rowid.rowid_block_number(rowid) block#,dbms_rowid.rowid_row_number(rowid) row# from guoyJoe_t1 where id=1; NAME FILE# BLOCK# ROW# ---------- ---------- ---------- ---------- guoyJoe 5 20877 0 tom 5 20877 1
实际上用BBED恢复UPDATE前的值不难,主要是要了解内部原理和块格式