oracle 基于数据挖掘的不彻底恢复

时间  2019-11-19
标签 oracle 基于 数据挖掘 不彻底 恢复 栏目 Oracle 繁體版
原文   原文链接

    因为某种误操做须要恢复数据库。固然咱们都知道，假如本身以前有备份数据库能够用rman进行恢复，可是这样的状况就会恢复倒备份的时刻状态，而不是误操做的时候的状态，也能够叫作形成恢复过分了。因而咱们能够用不彻底恢复。数据库

注意：不彻底恢复是须要关闭数据库的，因此对于7*24的数据库不适用，并且在误操做以前是要有备份的。oracle

下面咱们来模拟数据误操做之后的不彻底恢复。spa

1    备份数据库rest

RMAN> backup database;

Starting backup at 10-APR-17
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00001 name=/u01/oracle/oradata/orcl/system01.dbf
input datafile file number=00002 name=/u01/oracle/oradata/orcl/sysaux01.dbf
input datafile file number=00005 name=/u01/oracle/oradata/orcl/user02.dbf
input datafile file number=00006 name=/u01/oracle/oradata/orcl/tmpspace0327
input datafile file number=00007 name=/u01/oracle/oradata/orcl/undotbs02.dbf
input datafile file number=00008 name=/u01/oracle/oradata/orcl/example.dbf
input datafile file number=00004 name=/u01/oracle/oradata/orcl/users01.dbf
channel ORA_DISK_1: starting piece 1 at 10-APR-17
channel ORA_DISK_1: finished piece 1 at 10-APR-17
piece handle=/tmp/0us1cc3q_1_1 tag=TAG20170410T225138 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:01:25
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at 10-APR-17
channel ORA_DISK_1: finished piece 1 at 10-APR-17
piece handle=/tmp/0vs1cc6f_1_1 tag=TAG20170410T225138 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:02
Finished backup at 10-APR-17

2    删数据（彻底删除）日志

SQL> drop table emp purge;

Table dropped.

3    数据挖掘code

    数据不彻底恢复的时候咱们要知道scn或者时间点。须要从日志挖掘中找。ci

SQL> desc dbms_logmnr;
PROCEDURE ADD_LOGFILE
 Argument Name			Type			In/Out Default?
 ------------------------------ ----------------------- ------ --------
 LOGFILENAME			VARCHAR2		IN
 OPTIONS			BINARY_INTEGER		IN     DEFAULT
# 在dbms_logmnr这个包中有一个过程ADD_LOGFILE ，这个就是须要把挖掘的日志添加进去，再打开挖掘，能够看到参数只须要用一个logfilename ，日志文件名，因此咱们须要找到删除数据的时候适用的日志文件是哪一个
SQL> select group#,members,status from v$log;

    GROUP#    MEMBERS STATUS
---------- ---------- ----------------
	 1	    1 CURRENT
	 2	    1 INACTIVE
	 3	    1 INACTIVE
# 能够看出当前适用的日志文件是1
SQL> select group#,member,status from v$logfile;

    GROUP#
----------
MEMBER								       STATUS
---------------------------------------------------------------------- -------
	 3
/u01/oracle/oradata/orcl/redo03.log

	 2
/u01/oracle/oradata/orcl/redo02.log

	 1
/u01/oracle/oradata/orcl/redo01.log
# 看以看出日志文件1 的名字是‘/u01/oracle/oradata/orcl/redo01.log’

 

把日志文件添加进挖掘里面get

SQL> exec dbms_logmnr.add_logfile('/u01/oracle/oradata/orcl/redo01.log');

PL/SQL procedure successfully completed.

 

启动日志挖掘input

SQL> desc dbms_logmnr;
PROCEDURE START_LOGMNR
 Argument Name			Type			In/Out Default?
 ------------------------------ ----------------------- ------ --------
 STARTSCN			NUMBER			IN     DEFAULT
 ENDSCN 			NUMBER			IN     DEFAULT
 STARTTIME			DATE			IN     DEFAULT
 ENDTIME			DATE			IN     DEFAULT
 DICTFILENAME			VARCHAR2		IN     DEFAULT
 OPTIONS			BINARY_INTEGER		IN     DEFAULT
# 咱们能够看到包dbms_logmnr里面有一个start_logmnr 过程，用这个过程启动挖掘
SQL> execute dbms_logmnr.START_LOGMNR(options=>dbms_logmnr.dict_from_online_catalog);

PL/SQL procedure successfully completed.
# 启动挖掘成功

从挖掘中找到误操做数据当时的scn和时间，在v$logmnr_contents;数据挖掘

SQL> select scn,to_char(TIMESTAMP,'yyyy-mm-dd hh24:mi:ss') TIMESTAMP,SQL_REDO,SQL_UNDO from v$logmnr_contents where table_name = 'EMP';

       SCN TIMESTAMP		SQL_REDO	     SQL_UNDO
---------- -------------------- -------------------- --------------------
   2507301 2017-04-10 22:54:49	drop table emp purge
				;

到此为止，咱们已经挖掘成功，找到scn和时间点

注意：若是用时间点恢复的时候要减1秒

最后关闭数据挖掘

SQL> exec dbms_logmnr.end_logmnr;

PL/SQL procedure successfully completed.

4    不彻底恢复

RMAN> shutdown immediate;

using target database control file instead of recovery catalog
database closed
database dismounted
Oracle instance shut down
#先关闭数据库
RMAN> startup mount;

connected to target database (not started)
Oracle instance started
database mounted

Total System Global Area     584568832 bytes

Fixed Size                     2230552 bytes
Variable Size                444597992 bytes
Database Buffers             130023424 bytes
Redo Buffers                   7716864 bytes
#启动倒mount状态下
RMAN> run{
2> set until scn 2507301;
3> restore database;
4> recover database;
5> alter database open resetlogs;
6> }

executing command: SET until clause

Starting restore at 10-APR-17
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=137 device type=DISK

channel ORA_DISK_1: starting datafile backup set restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
channel ORA_DISK_1: restoring datafile 00001 to /u01/oracle/oradata/orcl/system01.dbf
channel ORA_DISK_1: restoring datafile 00002 to /u01/oracle/oradata/orcl/sysaux01.dbf
channel ORA_DISK_1: restoring datafile 00004 to /u01/oracle/oradata/orcl/users01.dbf
channel ORA_DISK_1: restoring datafile 00005 to /u01/oracle/oradata/orcl/user02.dbf
channel ORA_DISK_1: restoring datafile 00006 to /u01/oracle/oradata/orcl/tmpspace0327
channel ORA_DISK_1: restoring datafile 00007 to /u01/oracle/oradata/orcl/undotbs02.dbf
channel ORA_DISK_1: restoring datafile 00008 to /u01/oracle/oradata/orcl/example.dbf
channel ORA_DISK_1: reading from backup piece /tmp/0us1cc3q_1_1
channel ORA_DISK_1: piece handle=/tmp/0us1cc3q_1_1 tag=TAG20170410T225138
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:01:15
Finished restore at 10-APR-17

Starting recover at 10-APR-17
using channel ORA_DISK_1

starting media recovery
media recovery complete, elapsed time: 00:00:01

Finished recover at 10-APR-17

database opened
# 用上面run{}脚本进行恢复，restore，recover,open resetlogs;
# 成功

5    验证

SQL> desc emp;
 Name					   Null?    Type
 ----------------------------------------- -------- ----------------------------
 EMPNO					   NOT NULL NUMBER(4)
 ENAME						    VARCHAR2(10)
 JOB						    VARCHAR2(9)
 MGR						    NUMBER(4)
 HIREDATE					    DATE
 SAL						    NUMBER(7,2)
 COMM						    NUMBER(7,2)
 DEPTNO 					    NUMBER(2)

SQL> select count(*) from emp;

  COUNT(*)
----------
# 被删除的emp表恢复成功

6    从新备份数据库

注意：恢复倒误操做时刻成功了，可是误操做以后作的事情就会丢失，因此要谨慎，并且须要关闭数据。

在oracle11g 中还能够在线克隆的方式避免关闭数据库：

方法大体步骤：

    1） 在线克隆一个备库

    2）在备库中进行不彻底恢复

    3） 把备库中部彻底恢复成功的数据拷贝到主库

这样既能够不用关闭数据库，也解决了不彻底恢复有可能形成的部分数据丢失。具体操做演示这里就不说了。

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