Oracle bbed的使用(找回DELETE的行)
当一行数据被DELETE掉后，实际并没有删除，而是在相应的标记为打了一删除标记，通过BBED修改这个标记就可以把行数据找回来，下面做这个小实验：
1、 创建实验表，并插入一些数据
SQL> create tablelihm.t(msg varchar(20),id int) tablespace users;
Tablecreated.
SQL> insert into lihm.tvalues('aaa',1);
1row created.
SQL> insert into lihm.tvalues('bbb',2);
1row created.
SQL> insert into lihm.tvalues('ccc',3);
1row created.
SQL> commit;
Commitcomplete.
SQL> select * fromlihm.t;
MSG ID
-----------------
aaa 1
bbb 2
ccc 3
2、 生成filelist文件
SQL>l
1* select file#||' '||name||' '||bytes from v$datafile
SQL>/
1/u02/app/oracle/oradata/ora10g/system01.dbf 461373440
2/u02/app/oracle/oradata/ora10g/undotbs01.dbf 26214400
3/u02/app/oracle/oradata/ora10g/sysaux01.dbf 251658240
4 /u02/app/oracle/oradata/ora10g/users01.dbf5242880
[oracle@hadoop1bbed]$ cat filelist.txt
1 /u02/app/oracle/oradata/ora10g/system01.dbf461373440
2/u02/app/oracle/oradata/ora10g/undotbs01.dbf 26214400
3 /u02/app/oracle/oradata/ora10g/sysaux01.dbf251658240
4 /u02/app/oracle/oradata/ora10g/users01.dbf5242880
[oracle@hadoop1bbed]$ cat bbed.par
blocksize=8192
listfile=/home/oracle/bbed/filelist.txt
mode=edit
password=blockedit
3、 查看表数据对应的块信息
SQL> l
1 select rowid,
2 dbms_rowid.rowid_relative_fno(rowid)file_no,
3 dbms_rowid.rowid_block_number(rowid)block_no,
4 dbms_rowid.rowid_row_number(rowid) row_no,
5 msg,
6 id
7* from lihm.t
SQL>/
ROWID FILE_NO BLOCK_NO ROW_NO MSG ID
---------------------------- ---------- ---------- ---------- ----------
AAAMpWAAEAAAAA8AAA 4 60 0 aaa 1
AAAMpWAAEAAAAA8AAB 4 60 1 bbb 2
AAAMpWAAEAAAAA8AAC 4 60 2 ccc 3
4、监控修改前后状态标记的变化
执行DELETE前查看记录状态：
BBED>p *kdbr[2]
rowdata[0]
----------
ub1 rowdata[0] @8158 0x2c
BBED>x /rcn
rowdata[0] @8158
----------
flag@8158: 0x2c (KDRHFL, KDRHFF, KDRHFH)
lock@8159: 0x01
cols@8160: 2
col 0[3] @8161: ccc
col 1[2] @8165: 3
删除表数据：
SQL>delete from lihm.t where id=3;
1 row deleted.
SQL>commit;
Commit complete.
SQL>alter system flush buffer_cache;
System altered.
再次查看记录状态：
BBED>p *kdbr[2]
rowdata[0]
----------
ub1 rowdata[0] @8158 0x3c
BBED>x /rcn
rowdata[0] @8158
----------
flag@8158: 0x3c (KDRHFL, KDRHFF, KDRHFD,KDRHFH)
lock@8159: 0x02
cols@8160: 0
可以看到flag lock cols已经发生了改变，我们通过BBED修改回来：
BBED>m /x 2c dba 4,60 offset 8158
Warning: contents of previous BIFILE will belost. Proceed? (Y/N) Y
File:/u02/app/oracle/oradata/ora10g/users01.dbf (4)
Block:60 Offsets: 8158 to8167 Dba:0x0100003c
------------------------------------------------------------------------
2c020203 63636302 c104
<32bytes per line>
BBED>p *kdbr[2]
rowdata[0]
----------
ub1 rowdata[0] @8158 0x2c
BBED>x /rcn
rowdata[0] @8158
----------
flag@8158: 0x2c (KDRHFL, KDRHFF, KDRHFH)
lock@8159: 0x02
cols@8160: 2
col 0[3] @8161: ccc
col 1[2] @8165: 3
可以看到BBED已经可以看到记录了
5、 通过SQL语句查看记录情况
SQL>select * from lihm.t;
MSG ID
---------- ----------
aaa 1
bbb 2
ccc 3
可以看到数据又重新可见了。