Use bbed to directly modify the Oracle data file to restore Deleted Data

Today I will write a simple article about how to use the combination of Oracle bbed and Oracle Data File block formatsArticle. To better understand something inside the database. A record is deleted

Then, how to directly restore data by directly modifying ORACLE data files. Of course, no matter whether the table is deleted, dropped, or teuncate, there are a lot of restoration operations.

Method. This is only one of the studies. In order to play a role. (For Reprinted data, please indicate the source www.sosdb.com)

The entire process is explained in detail through specific experiments as follows:

1. Create tablespace sosdbcom datafile '/ora/sosdbcom. dbf' size 5 m;

2. Create Table sosdb (sos01 varchar2 (15), sos02 number (4) tablespace sosdbcom;

3. insert into sosdb values ('www .sosdb.com ', 86)

Insert into sosdb select * From sosdb.com;

Insert into sosdb select * From sosdb.com;

Commit;

4. Select * From sosdb;

Sos01 sos02

-------------------------

Www.sosdb.com 86

Www.sosdb.com 86

Www.sosdb.com 86

Www.sosdb.com 86

Now let's delete one. Select the first one.

5. Delete from sosdb where roenum <2;

Commit;

Now look

SQL> select * From sosdb;

Sos01 sos02

-------------------------

Www.sosdb.com 86

Www.sosdb.com 86

Www.sosdb.com 86

SQL>

Okay, the rest of the work is how to modify the block of Oracle datafile
To restore the deleted record.

You need to use bbed here. For the usage of bbed, see:

Http://www.sosdb.com/jdul/dispbbs.asp? Boardid = 1 & id = 237 & page = 1

Write a bbed parameter file par. BBD

Blocksize = 8192

Listfile+a.txt

Mode = Edit

Write an a.txt File

15/ora/sosdbcom. DBF 5251072

Open bbed:

[Oracle @ mail ora] $./bbed parfile = par. BBD

Dump File 14 block 10 count 8192

Let's take a look at this block dump and we will find that the last part is:

00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 2c00020d 77772e 736f7364 622e636f 6d02c157

2c00020d 77772e 736f7364 622e636f 6d02c157 2c00020d 7777772e 736f7364

622e636f 6d02c157 3c02020d 77772e 736f7364 622e636f 6d02c157 01064cd4

The analysis will find that the mark of each row is 2c00, but one is 3c02. In fact, this is the mark of the deleted record. We only

You need to modify the mark, and then modify some of the mark of the data file.

The modification method is as follows:

Bbed> Modify/X 2C file 14 block 10 offset 8168

Bbed> Modify/x 00 file 14 block 10 offset 8169

After modification, the block status is upt. Use the sum command to make it valid.

Bbed> sum file 14 block 10 apply

Restart the Oracle database and query the table sosdb:

SQL> Conn/As sysdba

Connected to an idle instance.

SQL> startup

Oracle instance started.

Total system global area 236000356 bytes

Fixed size 451684 bytes

Variable Size 201326592 bytes

Database buffers 33554432 bytes

Redo buffers 667648 bytes

Database mounted.

Database opened.

SQL> select * From sosdb;

Sos01 sos02

-------------------------

Www.sosdb.com 86

Www.sosdb.com 86

Www.sosdb.com 86

Www.sosdb.com 86

OK. At this point, the deleted record is successfully restored.

Here is just a simple example. In fact, many times we can use this method to do other work, especially recovery.