RMAN作为Oracle强大的备份恢复工具，可以协助我们恢复数据库到指定时间点，这便是Oracle不完全恢复的一种体现，通过这种方法可以找回我们曾经丢失的数据。这里以找回误TRUNCATE表数据为例给大家演示一下RMAN的不完全恢复功能。
1.调整数据库为归档模式
[oracle@hear ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Thu Jul 25 09:28:42 2019
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> archive log list;
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/app/oracle/product/11.2.0/dbhome_1/dbs/arch
Oldest online log sequence 4
Next log sequence to archive 6
Current log sequence 6
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.
Total System Global Area 2137886720 bytes
Fixed Size 2254952 bytes
Variable Size 1744832408 bytes
Database Buffers 385875968 bytes
Redo Buffers 4923392 bytes
Database mounted.
SQL> alter database archivelog;
Database altered.
SQL> alter database open;
Database altered.
2.使用RMAN对数据库进行备份
备份数据库
[oracle@hear ~]$ rman target /
Recovery Manager: Release 11.2.0.4.0 - Production on Thu Jul 25 09:50:48 2019
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
connected to target database: HEARDB (DBID=3039837723)
RMAN> backup database;
查看备份信息:
RMAN> list backup;
List of Backup Sets
===================
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
20 Full 1.12G DISK 00:01:35 19-JUN-19
BP Key: 20 Status: AVAILABLE Compressed: NO Tag: TAG20190619T233050
Piece Name: /home/oracle/backup/system_0ru4hc1a_1_1
List of Datafiles in backup set 20
File LV Type Ckp SCN Ckp Time Name
---- -- ---- ---------- --------- ----
1 Full 1393463 19-JUN-19 /home/oracle/app/oradata/heardb/system01.dbf
2 Full 1393463 19-JUN-19 /home/oracle/app/oradata/heardb/sysaux01.dbf
3 Full 1393463 19-JUN-19 /home/oracle/app/oradata/heardb/undotbs01.dbf
4 Full 1393463 19-JUN-19 /home/oracle/app/oradata/heardb/users01.dbf
5 Full 1393463 19-JUN-19 /home/oracle/app/oradata/heardb/example01.dbf
3.模拟数据库故障——表的误r_user
SQL> select count(*) from caodeng.r_user;
COUNT(*)
----------
5
SQL> alter session set nls_date_format='yyyy-mm-dd';
Session altered.
SQL> select sysdate from dual;
SYSDATE
----------
2019-07-25
SQL> alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';
Session altered.
SQL> select sysdate from dual;
SYSDATE
-------------------
2019-07-25 09:36:12
删除表
SQL> truncate table caodeng.r_user;
Table truncated.
SQL> select count(*) from caodeng.r_user;
COUNT(*)
----------
0
4.使用RMAN恢复到故障发生之前的时间点
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.
Total System Global Area 2137886720 bytes
Fixed Size 2254952 bytes
Variable Size 1744832408 bytes
Database Buffers 385875968 bytes
Redo Buffers 4923392 bytes
Database mounted.
2）使用RMAN脚本恢复数据库到指定时间点
（1）恢复脚本如下:
run {
allocate channel c1 type disk;
allocate channel c2 type disk;
sql 'alter session set nls_date_format="yyyy-mm-dd hh24:mi:ss"';
set until time = '2019-07-25 09:36:12';
restore database;
recover database;
alter database open resetlogs;}
记录恢复过程:
RMAN> run {
allocate channel c1 type disk;
allocate channel c2 type disk;
sql 'alter session set nls_date_format="yyyy-mm-dd hh24:mi:ss"';
set until time = '2019-07-25 09:36:12';
restore database;
recover database;
alter database open resetlogs;}2> 3> 4> 5> 6> 7> 8>
using target database control file instead of recovery catalog
allocated channel: c1
channel c1: SID=1135 device type=DISK
allocated channel: c2
channel c2: SID=2267 device type=DISK
sql statement: alter session set nls_date_format="yyyy-mm-dd hh24:mi:ss"
executing command: SET until clause
Starting restore at 25-JUL-19
channel c1: starting datafile backup set restore
channel c1: specifying datafile(s) to restore from backup set
channel c1: restoring datafile 00001 to /home/oracle/app/oradata/heardb/system01.dbf
channel c1: restoring datafile 00002 to /home/oracle/app/oradata/heardb/sysaux01.dbf
channel c1: restoring datafile 00003 to /home/oracle/app/oradata/heardb/undotbs01.dbf
channel c1: restoring datafile 00004 to /home/oracle/app/oradata/heardb/users01.dbf
channel c1: restoring datafile 00005 to /home/oracle/app/oradata/heardb/example01.dbf
channel c1: reading from backup piece /home/oracle/backups/db_20190725_30u7h90d
channel c1: piece handle=/home/oracle/backups/db_20190725_30u7h90d tag=TAG20190725T082757
channel c1: restored backup piece 1
channel c1: restore complete, elapsed time: 00:01:36
Finished restore at 25-JUL-19
Starting recover at 25-JUL-19
starting media recovery
media recovery complete, elapsed time: 00:00:03
Finished recover at 25-JUL-19
database opened
released channel: c1
released channel: c2
5.验证恢复成果
[oracle@hear ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Thu Jul 25 09:44:29 2019
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> select count(*(^H
2
SQL> select count(*) from caodeng.r_user;
COUNT(*)
----------
5
SQL>
这样删除的r_user表的数据丢失的已经被完全成功恢复