rman backup 对于truncate和drop等相关操作的extent到底是怎么处理的,这里通过rman backup 结合odu证明出来,在较新版本的rman中,rman backup 并未完全的备份这些被认为不需要的extent.
创建模拟环境
SQL> select * from v$version;
BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - Prod
PL/SQL Release 10.2.0.4.0 - Production
CORE 10.2.0.4.0 Production
TNS for Linux: Version 10.2.0.4.0 - Production
NLSRTL Version 10.2.0.4.0 - Production
SQL> create tablespace xifenfei datafile '/u01/oracle/oradata/XFF/xifenfei01.dbf'
2 size 10m autoextend on maxsize 10g;
Tablespace created.
SQL> conn chf/xifenfei
Connected.
SQL> create table t_xifenfei tablespace xifenfei
2 as
3 select * from dba_objects;
Table created.
SQL> insert into t_xifenfei
2 select * from dba_objects;
50055 rows created.
SQL> commit;
Commit complete.
SQL> select BYTES from dba_free_space where TABLESPACE_NAME='XIFENFEI';
BYTES
----------
983040
SQL> select BYTES from v$datafile where name='/u01/oracle/oradata/XFF/xifenfei01.dbf';
BYTES
----------
12582912
SQL> select 12582912-983040 from dual;
12582912-983040
---------------
11599872
SQL> select object_id,data_object_id from dba_objects where object_name='T_XIFENFEI';
OBJECT_ID DATA_OBJECT_ID
---------- --------------
51833 51833
--这里我们得到信息有:
--1.dataobj#=51833
--2.使用数据文件空间为:11599872
rman备份no truncate table 数据文件
[oracle@xifenfei ~]$ rman target / Recovery Manager: Release 10.2.0.4.0 - Production on Thu Dec 15 06:00:05 2011 Copyright (c) 1982, 2007, Oracle. All rights reserved. connected to target database: XFF (DBID=3440302261) RMAN> backup tablespace xifenfei format '/u01/oracle/oradata/tmp/no_truncate_xifenfei'; Starting backup at 15-DEC-11 using target database control file instead of recovery catalog allocated channel: ORA_DISK_1 channel ORA_DISK_1: sid=158 devtype=DISK channel ORA_DISK_1: starting full datafile backupset channel ORA_DISK_1: specifying datafile(s) in backupset input datafile fno=00005 name=/u01/oracle/oradata/XFF/xifenfei01.dbf channel ORA_DISK_1: starting piece 1 at 15-DEC-11 channel ORA_DISK_1: finished piece 1 at 15-DEC-11 piece handle=/u01/oracle/oradata/tmp/no_truncate_xifenfei tag=TAG20111215T060343 comment=NONE channel ORA_DISK_1: backup set complete, elapsed time: 00:00:03 Finished backup at 15-DEC-11
truncate table 操作
[oracle@xifenfei ~]$ sqlplus / as sysdba SQL*Plus: Release 10.2.0.4.0 - Production on Thu Dec 15 06:03:58 2011 Copyright (c) 1982, 2007, Oracle. All Rights Reserved. Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> truncate table chf.t_xifenfei; Table truncated.
rman备份truncate table 数据文件
RMAN> backup tablespace xifenfei format '/u01/oracle/oradata/tmp/truncate_xifenfei'; Starting backup at 15-DEC-11 using target database control file instead of recovery catalog allocated channel: ORA_DISK_1 channel ORA_DISK_1: sid=140 devtype=DISK channel ORA_DISK_1: starting full datafile backupset channel ORA_DISK_1: specifying datafile(s) in backupset input datafile fno=00005 name=/u01/oracle/oradata/XFF/xifenfei01.dbf channel ORA_DISK_1: starting piece 1 at 15-DEC-11 channel ORA_DISK_1: finished piece 1 at 15-DEC-11 piece handle=/u01/oracle/oradata/tmp/truncate_xifenfei tag=TAG20111215T060445 comment=NONE channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01 Finished backup at 15-DEC-11 [root@xifenfei ~]# ls -l /u01/oracle/oradata/tmp/*_xifenfei -rw-r----- 1 oracle oinstall 11640832 Dec 15 06:03 /u01/oracle/oradata/tmp/no_truncate_xifenfei -rw-r----- 1 oracle oinstall 630784 Dec 15 06:04 /u01/oracle/oradata/tmp/truncate_xifenfei
odu挖rman备份前数据文件
ODU> unload dict CLUSTER C_USER# file_no: 1 block_no: 89 TABLE OBJ$ file_no: 1 block_no: 121 CLUSTER C_OBJ# file_no: 1 block_no: 25 CLUSTER C_OBJ# file_no: 1 block_no: 25 found IND$'s obj# 19 found IND$'s dataobj#:2,ts#:0,file#:1,block#:25,tab#:3 found TABPART$'s obj# 266 found TABPART$'s dataobj#:266,ts#:0,file#:1,block#:2121,tab#:0 found INDPART$'s obj# 271 found INDPART$'s dataobj#:271,ts#:0,file#:1,block#:2161,tab#:0 found TABSUBPART$'s obj# 278 found TABSUBPART$'s dataobj#:278,ts#:0,file#:1,block#:2217,tab#:0 found INDSUBPART$'s obj# 283 found INDSUBPART$'s dataobj#:283,ts#:0,file#:1,block#:2257,tab#:0 found IND$'s obj# 19 found IND$'s dataobj#:2,ts#:0,file#:1,block#:25,tab#:3 found LOB$'s obj# 151 found LOB$'s dataobj#:2,ts#:0,file#:1,block#:25,tab#:6 found LOBFRAG$'s obj# 299 found LOBFRAG$'s dataobj#:299,ts#:0,file#:1,block#:2393,tab#:0 ODU> scan extent tablespace 6 scan extent start: 2011-12-15 06:12:28 scanning extent... scanning extent finished. scan extent completed: 2011-12-15 06:12:28 ODU> unload table chf.t_xifenfei object 51833 Unloading table: T_XIFENFEI,object ID: 51833 Unloading segment,storage(Obj#=51833 DataObj#=51833 TS#=6 File#=5 Block#=11 Cluster=0) 100110 rows unloaded --这里可以看到odu全部找到被truncate掉的记录条数
使用rman 备份后数据文件
SQL> shutdown immediate Database closed. Database dismounted. ORACLE instance shut down. SQL> exit Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - Production With the Partitioning, OLAP, Data Mining and Real Application Testing options [oracle@xifenfei odu]$ rm /u01/oracle/oradata/XFF/xifenfei01.dbf [oracle@xifenfei odu]$ rman target / Recovery Manager: Release 10.2.0.4.0 - Production on Thu Dec 15 06:14:00 2011 Copyright (c) 1982, 2007, Oracle. All rights reserved. connected to target database (not started) RMAN> startup mount; Oracle instance started database mounted Total System Global Area 318767104 bytes Fixed Size 1267236 bytes Variable Size 104860124 bytes Database Buffers 205520896 bytes Redo Buffers 7118848 bytes RMAN> restore datafile 5; Starting restore at 15-DEC-11 using target database control file instead of recovery catalog allocated channel: ORA_DISK_1 channel ORA_DISK_1: sid=157 devtype=DISK channel ORA_DISK_1: starting datafile backupset restore channel ORA_DISK_1: specifying datafile(s) to restore from backup set restoring datafile 00005 to /u01/oracle/oradata/XFF/xifenfei01.dbf channel ORA_DISK_1: reading from backup piece /u01/oracle/oradata/tmp/truncate_xifenfei channel ORA_DISK_1: restored backup piece 1 piece handle=/u01/oracle/oradata/tmp/truncate_xifenfei tag=TAG20111215T060445 channel ORA_DISK_1: restore complete, elapsed time: 00:00:01 Finished restore at 15-DEC-11
odu挖rman还原后数据文件
ODU> scan extent tablespace 6 scan extent start: 2011-12-15 06:14:43 scanning extent... scanning extent finished. scan extent completed: 2011-12-15 06:14:43 ODU> unload table chf.t_xifenfei object 51833 Unloading table: T_XIFENFEI,object ID: 51833 Unloading segment,storage(Obj#=51833 DataObj#=51833 TS#=6 File#=5 Block#=11 Cluster=0) 4774 rows unloaded --odu只找到极少数数据4774/100110
通过odu挖rman备份前和备份后的数据文件,得知rman backup备份的过程,对绝大多数truncate的表的原始数据未正常备份(为什么是绝大多数,我无法给出解释),这里也可以看出rman backup并非是真正意义上的完全物理上复制(和rman copy还是有区别,copy不能完全被取代)
