deleted

构建测试的环境并模拟删除数据：

SQL> create user luda identified by luda default tablespace users;

User created.

SQL> grant dba to luda;

Grant succeeded.

SQL> alter system checkpoint;

System altered.

SQL>
SQL> conn luda/luda
Connected.
SQL> create table t1 as select * from dba_objects where rownum < 10001;

Table created.

SQL> create table t2 as select object_id,object_name from dba_objects where rownum < 100;

Table created.

SQL> commit;

Commit complete.

SQL> alter system checkpoint;

System altered.

#rows before delete from luda.t2
SQL> select count(*) from t2;

  COUNT(*)
----------
        99

#delete 90rows from luda

SQL> delete from luda.t2 where rownum < 91;

90 rows deleted.

SQL> commit;

Commit complete.

SQL> select count(*) from luda.t2;

  COUNT(*)
----------
         9

SQL> alter system checkpoint;

System altered.

加载mdata

#using mdata unload data that have deleted from luda.t2
MDATA>reload dict
Start reload dict,Sun Jan 11 00:01:50 CST 2015
SQLException: State:   X0X95 Severity: 30000
Operation 'TRUNCATE TABLE' cannot be performed on object 'IDUL_OBJ' because there is an open ResultSet dependent on that object.
load BOOTSTRAP$ success.
load TAB$ success.
load COL$ success.
load OBJ$ success.
load USER$ success.
load PROPS$ success.
load TABPART$ success.
load TABSUBPART$ success.
load IND$ success.
End reload dict,Sun Jan 11 00:01:56 CST 2015,reload success.

通过unload的功能恢复出delete数据

MDATA>unload table luda.t2 only deleted data
load only deleted data,schema:LUDA;tab:T2
tabName:LUDA.T2,dic_obj:com.olm.b.H@2d6636,getFileid:4,getBlockid:187
90 rows unloaded

退出mdata切换到恢复出数据的目录，这时候将恢复出的数据使用sqlloadl恢复到表中

#then u can find the unload data at /oracle/mdata/data
[root@DB01 data]# ls -lFrt
-rw-r--r-- 1 oracle oinstall    1042 Jan 11 00:02 LUDA.T2.dat
-rw-r--r-- 1 oracle oinstall     204 Jan 11 00:02 LUDA.T2.ctl
...

这里介绍2个delete的功能
第一种是unload表数据时候包含被删除数据

using mdata unload luda.t2's data contrain deleted data
MDATA>unload table luda.t2 contain deleted data
unload schema:LUDA;tab:T2 contain deleted data
tabName:LUDA.T2,dic_obj:com.olm.b.H@a0b1e1,getFileid:4,getBlockid:187
99 rows unloaded

第二种是unload表数据库时候不包含被删除数据

# using mdata unload luda.t2's data is not contrain deleted data
MDATA>unload table luda.t2
unload schema:LUDA;tab:T2
tabName:LUDA.T2,dic_obj:com.olm.b.H@1c76b8d,getFileid:4,getBlockid:187
9 rows unloaded