20、oracle用户管理恢复

下面会一一讲解控制文件、redo文件及非归档模式、归档模式数据文件丢失的情况下，如何恢复数据？

(1)控制文件(controlfile)丢失
在做恢复实验之前，先备份好数据。

案例1、模拟一个控制文件丢失
select name from v$controlfile;
SQL> select name from v$controlfile;

NAME
--------------------------------------------------------------------------------
/u02/oracle/oradata/orcl/control01.ctl
/u02/oracle/oradata/orcl/control02.ctl

删除其中一个控制文件
rm -rf /u02/oracle/oradata/orcl/control01.ctl

alter system switch logfile;
create tablespace hello datafile '/u02/oracle/oradata/orcl/hello01.dbf';

SQL> create tablespace hello datafile '/u02/oracle/oradata/orcl/hello01.dbf';
create tablespace hello datafile '/u02/oracle/oradata/orcl/hello01.dbf'
*
ERROR at line 1:
ORA-00210: cannot open the specified control file
ORA-00202: control file: '/u02/oracle/oradata/orcl/control01.ctl'
ORA-27041: unable to open file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3

数据库启动不起来
SQL> startup
ORACLE instance started.

Total System Global Area 2772574208 bytes
Fixed Size 2256472 bytes
Variable Size 771752360 bytes
Database Buffers 1979711488 bytes
Redo Buffers 18853888 bytes
ORA-00205: error in identifying control file, check alert log for more info

SQL> select status from v$instance;

STATUS
------------
STARTED

查看alert log内容如下：
tail -f /u02/oracle/diag/rdbms/orcl/orcl/trace/alert_orcl.log

ORA-00210: cannot open the specified control file
ORA-00202: control file: '/u02/oracle/oradata/orcl/control01.ctl'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
Wed Aug 30 23:30:34 2017
Checker run found 1 new persistent data failures
ORA-205 signalled during: ALTER DATABASE MOUNT...

如何恢复控制文件呢？
cp /u02/oracle/oradata/orcl/control02.ctl /u02/oracle/oradata/orcl/control01.ctl

ALTER DATABASE MOUNT;
ALTER DATABASE open;

案例2、控制文件全部丢失。(前提控制文件有备份)
alter database backup controlfile to '/u02/ctlbak001';（备份）

rm -rf /u02/oracle/oradata/orcl/control01.ctl
rm -rf /u02/oracle/oradata/orcl/control02.ctl

SQL> startup
ORACLE instance started.

Total System Global Area 2772574208 bytes
Fixed Size 2256472 bytes
Variable Size 771752360 bytes
Database Buffers 1979711488 bytes
Redo Buffers 18853888 bytes
ORA-00205: error in identifying control file, check alert log for more info

ORA-00202: control file: '/u02/oracle/oradata/orcl/control02.ctl'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
ORA-00210: cannot open the specified control file
ORA-00202: control file: '/u02/oracle/oradata/orcl/control01.ctl'

如何恢复控制文件呢？
cp /u02/ctlbak001 /u02/oracle/oradata/orcl/control01.ctl
cp /u02/ctlbak001 /u02/oracle/oradata/orcl/control02.ctl
启动数据库还是报错
SQL> startup
ORACLE instance started.

Total System Global Area 2772574208 bytes
Fixed Size 2256472 bytes
Variable Size 771752360 bytes
Database Buffers 1979711488 bytes
Redo Buffers 18853888 bytes
Database mounted.
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open

SQL> select GROUP#,FIRST_CHANGE#,NEXT_CHANGE# from v$log;

GROUP# FIRST_CHANGE# NEXT_CHANGE#
---------- ------------- ------------
1 1520101 1520104
3 1540267 2.8147E+14
2 1520104 1540267

继续执行如下命令：
recover database using backup controlfile;

SQL> recover database using backup controlfile;
ORA-00279: change 1540268 generated at 08/30/2017 23:34:57 needed for thread 1
ORA-00289: suggestion : /u02/arch/1_51_944544087.dbf
ORA-00280: change 1540268 for thread 1 is in sequence #51

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
auto
ORA-00308: cannot open archived log '/u02/arch/1_51_944544087.dbf'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3

ORA-00308: cannot open archived log '/u02/arch/1_51_944544087.dbf'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3

SQL> select GROUP#,MEMBER from v$logfile;

GROUP#

MEMBER
--------------------------------------------------------------------------------
3
/u02/oracle/oradata/orcl/redo03.log

2
/u02/oracle/oradata/orcl/redo02.log

1
/u02/oracle/oradata/orcl/redo01.log

通过上面分析，可以从/u02/oracle/oradata/orcl/redo03.log 恢复控制文件。
继续执行recover database using backup controlfile 命令
SQL> recover database using backup controlfile
ORA-00279: change 1540268 generated at 08/30/2017 23:34:57 needed for thread 1
ORA-00289: suggestion : /u02/arch/1_51_944544087.dbf
ORA-00280: change 1540268 for thread 1 is in sequence #51

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
/u02/oracle/oradata/orcl/redo03.log
Log applied.
Media recovery complete.

最后执行命令：
alter database open resetlogs;
搞定。

方法2：通过rman备份恢复控制文件。
下面通过rman备份控制文件来实验：
rman target /

RMAN> show all;

using target database control file instead of recovery catalog
RMAN configuration parameters for database with db_unique_name ORCL are:
CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE MAXSETSIZE TO UNLIMITED; # default
CONFIGURE ENCRYPTION FOR DATABASE OFF; # default
CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default
CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default
CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/u02/oracle/app/dbs/snapcf_orcl.f'; # default

可以通过 CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
看到rman没有自动备份控制文件。
rman手动备份控制文件
backup current controlfile;
RMAN> backup current controlfile;

Starting backup at 31-AUG-17
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=39 device type=DISK
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
channel ORA_DISK_1: starting piece 1 at 31-AUG-17
channel ORA_DISK_1: finished piece 1 at 31-AUG-17
piece handle=/u02/oracle/app/dbs/02sd9jb1_1_1 tag=TAG20170831T125145 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 31-AUG-17

下面模拟删除所有控制文件
rm -rf /u02/oracle/oradata/orcl/control01.ctl
rm -rf /u02/oracle/oradata/orcl/control02.ctl

shutdown immediate;
startup;

进入rman
[oracle@oracle250 ~]$ rman target /

Recovery Manager: Release 11.2.0.4.0 - Production on Thu Aug 31 13:11:34 2017

Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.

connected to target database: ORCL (not mounted)

通过rman备份的控制文件路径恢复。
restore controlfile from '/u02/oracle/app/dbs/02sd9jb1_1_1';

RMAN> restore controlfile from '/u02/oracle/app/dbs/02sd9jb1_1_1';

Starting restore at 31-AUG-17
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=21 device type=DISK

channel ORA_DISK_1: restoring control file
channel ORA_DISK_1: restore complete, elapsed time: 00:00:03
output file name=/u02/oracle/oradata/orcl/control01.ctl
output file name=/u02/oracle/oradata/orcl/control02.ctl
Finished restore at 31-AUG-17

执行命令：
alter database mount;

alter database open;

SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open

通过数据文件和控制文件的检查点信息可以看出，数据文件比控制文件的检查点要小。
col FILE for a10;
col Name for a20;
col CHECKPOINT_CHANGE for a10;

select FILE#,Name,CHECKPOINT_CHANGE# from v$datafile;
select FILE#,Name,CHECKPOINT_CHANGE# from v$datafile_header;

继续执行recover database using backup controlfile 命令

SQL> select GROUP#,FIRST_CHANGE#,NEXT_CHANGE# from v$log;

GROUP# FIRST_CHANGE# NEXT_CHANGE#
---------- ------------- ------------
1 1540805 2.8147E+14
3 0 0
2 0 0

使用redo日志推进控制文件。
SQL> recover database using backup controlfile;
ORA-00279: change 1561276 generated at 08/31/2017 00:16:02 needed for thread 1
ORA-00289: suggestion : /u02/arch/1_1_953424962.dbf
ORA-00280: change 1561276 for thread 1 is in sequence #1

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
/u02/oracle/oradata/orcl/redo01.log
Log applied.
Media recovery complete.

最后执行命令：
alter database open resetlogs;
搞定。

注意：alter database open resetlogs; 这个命令，表示所有备份都失效了，要重新热备份哦。

方法3：通过trace恢复控制文件
问题：如果控制文件没有备份、rman也没有备份控制文件，只有备份trace文件，如何恢复控制文件呢？

首先，备份 alter database backup controlfile to trace as '/u02/ctlbak.trace';

然后模拟故障：删除控制文件：
rm -rf /u02/oracle/oradata/orcl/control01.ctl
rm -rf /u02/oracle/oradata/orcl/control02.ctl

根据trace文件重建控制文件：
CREATE CONTROLFILE REUSE DATABASE "ORCL" NORESETLOGS ARCHIVELOG
MAXLOGFILES 16
MAXLOGMEMBERS 3
MAXDATAFILES 100
MAXINSTANCES 8
MAXLOGHISTORY 292
LOGFILE
GROUP 1 '/u02/oracle/oradata/orcl/redo01.log' SIZE 50M BLOCKSIZE 512,
GROUP 2 '/u02/oracle/oradata/orcl/redo02.log' SIZE 50M BLOCKSIZE 512,
GROUP 3 '/u02/oracle/oradata/orcl/redo03.log' SIZE 50M BLOCKSIZE 512
-- STANDBY LOGFILE
DATAFILE
'/u02/oracle/oradata/orcl/system01.dbf',
'/u02/oracle/oradata/orcl/sysaux01.dbf',
'/u02/oracle/oradata/orcl/undotbs01.dbf',
'/u02/oracle/oradata/orcl/users01.dbf',
'/u02/oracle/oradata/orcl/test01.dbf',
'/u02/oracle/oradata/orcl/rrr.dbf',
'/u02/oracle/oradata/orcl/tttt.dbf',
'/u02/oracle/oradata/orcl/tttt02.dbf',
'/u02/oracle/oradata/orcl/tttt03.dbf'
CHARACTER SET AL32UTF8

Control file created.

查看数据库状态：
SQL> select status from v$instance;

STATUS
------------
MOUNTED

alter database open;

SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-01113: file 1 needs media recovery
ORA-01110: data file 1: '/u02/oracle/oradata/orcl/system01.dbf';

SQL> select GROUP#,SEQUENCE#,FIRST_CHANGE#,NEXT_CHANGE# from v$log;

使用redo推进控制文件。
SQL> recover database using backup controlfile;
ORA-00279: change 1562427 generated at 08/31/2017 13:44:20 needed for thread 1
ORA-00289: suggestion : /u02/arch/1_1_953472820.dbf
ORA-00280: change 1562427 for thread 1 is in sequence #1

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
/u02/oracle/oradata/orcl/redo01.log
Log applied.
Media recovery complete.
SQL> alter database open resetlogs;
Database altered.

最后也要重新备份数据库。

(2)重做日志丢失
如果丢失重做日志文件组中的某个成员，并且组中至少还有一个成员，影响如下：
不会影响实例的正常操作，
通过删除丢失的日志成员，在添加新成员的方式来恢复。
如果日志切换，该日志已经归档(不是current log)，则可以清空该日志组，然后重建丢失的日志成员。

在做实验之前，先做redo log 的多路复用。
select GROUP#, member from v$logfile;
GROUP# MEMBER
---------- --------------------------------------------------
1 /u02/oracle/oradata/orcl/redo01.log
3 /u02/oracle/oradata/orcl/redo03.log
2 /u02/oracle/oradata/orcl/redo02.log

下面多路复用。
alter database add logfile member '/u01/redo/redo01_1.log' to group 1;
alter database add logfile member '/u01/redo/redo02_1.log' to group 2;
alter database add logfile member '/u01/redo/redo03_1.log' to group 3;

alter system switch logfile;

在查询结果如下：
select GROUP#, member,status from v$logfile order by 1;
SQL> select GROUP#, member,status from v$logfile order by 1;

GROUP# MEMBER STATUS
---------- -------------------------------------------------- -------
1 /u02/oracle/oradata/orcl/redo01.log
1 /u01/redo/redo01_1.log
2 /u02/oracle/oradata/orcl/redo02.log
2 /u01/redo/redo02_1.log
3 /u02/oracle/oradata/orcl/redo03.log
3 /u01/redo/redo03_1.log

6 rows selected.

STATUS为空表示redo可以使用。

select a.GROUP#,a.MEMBERS,a.ARCHIVED,a.STATUS,b.MEMBER,b.STATUS from v$log a,v$logfile b where a.GROUP#=b.GROUP# order by 1,3;

结果如下：
SQL> set lines 1200;
SQL> select a.GROUP#,a.MEMBERS,a.ARCHIVED,a.STATUS,b.MEMBER,b.STATUS from v$log a,v$logfile b where a.GROUP#=
b.GROUP# order by 1,3;
GROUP# MEMBERS ARC STATUS MEMBER STATUS
---------- ---------- --- ---------------- ---------------------------------------- -------
1 2 NO CURRENT /u02/oracle/oradata/orcl/redo01.log
1 2 NO CURRENT /u01/redo/redo01_1.log
2 2 YES INACTIVE /u02/oracle/oradata/orcl/redo02.log
2 2 YES INACTIVE /u01/redo/redo02_1.log
3 2 YES INACTIVE /u02/oracle/oradata/orcl/redo03.log
3 2 YES INACTIVE /u01/redo/redo03_1.log

6 rows selected.

案例1：删除日志组成员中一个(不管是不是单前的还是非单前的redolog,下面方法都适用。)
rm -rf /u02/oracle/oradata/orcl/redo03.log

alter system switch logfile;

tail -f /u02/oracle/diag/rdbms/orcl/orcl/trace/alert_orcl.log
看到报错信息如下：
ORA-00313: open failed for members of log group 3 of thread 1
ORA-00312: online log 3 thread 1: '/u02/oracle/oradata/orcl/redo03.log'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory

如何解决呢？先删除，在添加。
alter database drop logfile member '/u02/oracle/oradata/orcl/redo03.log';
alter database add logfile member '/u02/oracle/oradata/orcl/redo03.log' to group 3;

看log 没有报错：
Thread 1 advanced to log sequence 27 (LGWR switch)
Current log# 3 seq# 27 mem# 0: /u01/redo/redo03_1.log
Current log# 3 seq# 27 mem# 1: /u02/oracle/oradata/orcl/redo03.log
Thu Aug 31 19:28:50 2017
Archived Log entry 53 added for thread 1 sequence 26 ID 0x58497805 dest 1:
Archived Log entry 54 added for thread 1 sequence 26 ID 0x58497805 dest 2:
搞定。。。。。。

补充一下：
如果丢非当前的redolog 属于group 3 ,还可以这样解决：
alter database clear logfile group 3;

如果丢当前的redolog 属于group 3 ,还可以这样解决：
首先切换日志，让当前的redolog不属于group 3。
alter system switch logfile;
alter database checkpoint;
alter database clear logfile group 3;

案例2： 如果redo日志没有多路复用，如果redo日志丢了，怎么办？
alter database drop logfile member '/u01/redo/redo01_1.log';
alter database drop logfile member '/u01/redo/redo02_1.log';
alter database drop logfile member '/u01/redo/redo03_1.log';

目前redo日志没有多路复用，信息如下：
select GROUP#, member,status from v$logfile order by 1;
SQL> select GROUP#, member,status from v$logfile order by 1;

GROUP# MEMBER STATUS
---------- -------------------------------------------------- -------
1 /u02/oracle/oradata/orcl/redo01.log
2 /u02/oracle/oradata/orcl/redo02.log
3 /u02/oracle/oradata/orcl/redo03.log

select a.GROUP#,a.MEMBERS,a.ARCHIVED,a.STATUS,b.MEMBER,b.STATUS from v$log a,v$logfile b where a.GROUP#=b.GROUP# order by 1,3;

GROUP# MEMBERS ARC STATUS MEMBER STATUS
---------- ---------- --- ---------------- -------------------------------------------------- -------
1 1 YES ACTIVE /u02/oracle/oradata/orcl/redo01.log
2 1 NO CURRENT /u02/oracle/oradata/orcl/redo02.log
3 1 YES ACTIVE /u02/oracle/oradata/orcl/redo03.log

情况1：非当前redo日志丢失。
rm -rf /u02/oracle/oradata/orcl/redo03.log

模拟日志切换
alter system switch logfile;

报错信息：
ORA-00312: online log 3 thread 1: '/u02/oracle/oradata/orcl/redo03.log'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory

执行命令：
alter database clear logfile group 3;
SQL> alter database clear logfile group 3;

alter database clear logfile group 3
*
ERROR at line 1:
ORA-00350: log 3 of instance orcl (thread 1) needs to be archived
ORA-00312: online log 3 thread 1: '/u02/oracle/oradata/orcl/redo03.log'
发现日志没有归档：
select a.GROUP#,a.MEMBERS,a.ARCHIVED,a.STATUS,b.MEMBER,b.STATUS from v$log a,v$logfile b where a.GROUP#=b.GROUP# order by 1,3;
select name,SEQUENCE#,FIRST_CHANGE#,NEXT_CHANGE# from v$archived_log;

SQL> select a.GROUP#,a.MEMBERS,a.ARCHIVED,a.STATUS,b.MEMBER,b.STATUS from v$log a,v$logfile b where a.GROUP#=
b.GROUP# order by 1,3;
GROUP# MEMBERS ARC STATUS MEMBER STATUS
---------- ---------- --- ---------------- -------------------------------------------------- -------
1 1 NO INACTIVE /u02/oracle/oradata/orcl/redo01.log
2 1 NO CURRENT /u02/oracle/oradata/orcl/redo02.log
3 1 NO INACTIVE /u02/oracle/oradata/orcl/redo03.log

执行命令：alter system checkpoint;

使用清空非归档的日志组命令：
alter database clear unarchived logfile group 3;

SQL> alter database clear unarchived logfile group 3;

Database altered.

在看看日志组3，结果有了：
[oracle@oracle250 ~]$ ll /u02/oracle/oradata/orcl/redo03.log
-rw-r----- 1 oracle dba 52429312 Aug 31 21:29 /u02/oracle/oradata/orcl/redo03.log

在看看信息如下：
SQL> select a.GROUP#,a.MEMBERS,a.ARCHIVED,a.STATUS,b.MEMBER,b.STATUS from v$log a,v$logfile b where a.GROUP#=
b.GROUP# order by 1,3;
GROUP# MEMBERS ARC STATUS MEMBER STATUS
---------- ---------- --- ---------------- -------------------------------------------------- -------
1 1 NO CURRENT /u02/oracle/oradata/orcl/redo01.log
2 1 YES ACTIVE /u02/oracle/oradata/orcl/redo02.log
3 1 YES ACTIVE /u02/oracle/oradata/orcl/redo03.log
搞定了。。。。。。。。。。。。。。。
注意一下：之前的备份失效了，重新进行热备份哦。(因为删除了redo03日志，导致redo03日志没有归档，导致归档scn不连续。因此需要重新备份。)

情况2：如果当前日志组丢了怎么办？
select a.GROUP#,a.MEMBERS,a.ARCHIVED,a.STATUS,b.MEMBER,b.STATUS from v$log a,v$logfile b where a.GROUP#=b.GROUP# order by 1,3;

SQL> select a.GROUP#,a.MEMBERS,a.ARCHIVED,a.STATUS,b.MEMBER,b.STATUS from v$log a,v$logfile b where a.GROUP#=
b.GROUP# order by 1,3;
GROUP# MEMBERS ARC STATUS MEMBER STATUS
---------- ---------- --- ---------------- -------------------------------------------------- -------
1 1 NO CURRENT /u02/oracle/oradata/orcl/redo01.log
2 1 YES INACTIVE /u02/oracle/oradata/orcl/redo02.log
3 1 YES INACTIVE /u02/oracle/oradata/orcl/redo03.log

create table redo_01 as select * from scott.dept;

删除当前日志：
rm -rf /u02/oracle/oradata/orcl/redo01.log

SQL> startup;
ORACLE instance started.

Total System Global Area 2772574208 bytes
Fixed Size 2256472 bytes
Variable Size 771752360 bytes
Database Buffers 1979711488 bytes
Redo Buffers 18853888 bytes
Database mounted.
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1: '/u02/oracle/oradata/orcl/redo01.log'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3

数据库启动不了。具体信息上面。如何处理呢？
要利用热备份文件进行恢复，但是要丢失数据。。。。。
利用之前的备份文件还原回去。
之前的备份脚本如下：
[oracle@oracle250 ~]$ cat hotbackup.sh
sqlplus / as sysdba <<eof
!echo 'begin hot backup '
alter database begin backup;
!echo 'copy files'
!cp -v /u02/oracle/oradata/orcl/system01.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/sysaux01.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/undotbs01.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/users01.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/test01.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/rrr.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/tttt.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/tttt02.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/tttt03.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/temp01.dbf /home/oracle/hot_backup/

!echo 'end backup database'
alter database end backup;
exit
eof

还原数据。
cp /home/oracle/hot_backup/*.dbf /u02/oracle/oradata/orcl/

执行命令：
recover database until cancel;
SQL> recover database until cancel;
ORA-00279: change 1575684 generated at 08/31/2017 21:51:18 needed for thread 1
ORA-00289: suggestion : /u02/arch/1_34_953475378.dbf
ORA-00280: change 1575684 for thread 1 is in sequence #34

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}

CANCEL
ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below
ORA-01195: online backup of file 1 needs more recovery to be consistent
ORA-01110: data file 1: '/u02/oracle/oradata/orcl/system01.dbf'

填写 AUTO | CANCEL都不行，怎么办呢？
SQL> alter database open resetlogs;
alter database open resetlogs
*
ERROR at line 1:
ORA-01195: online backup of file 1 needs more recovery to be consistent
ORA-01110: data file 1: '/u02/oracle/oradata/orcl/system01.dbf'

也不行。。。。。z在线求解答！！！！！！

(3)非归档模式丢失数据文件(不完全恢复---丢数据)
如果数据库处于noarchivelog模式下，如果丢失了任何数据文件，请执行如下任务：
1、如果实例没有关闭，请关闭实例
2、从备份还原整个数据库，包括所有数据文件、控制文件和重做redo文件。
3、打开数据库
4、让用户重新输入自上次备份以来所做的所有更改。

startup mount;
alter database noarchivelog;//改成非归档模式！！！！！！！
archive log list;
做一次冷备份。
select * from v$log;
select current_scn from v$database;

创建一张表，insert 一些数据。

影响：只能还原到备份之前的数据。备份之后的所有操作数据都丢了，好悲吹。这里我就不做实验了。
备注：数据库处于非归档状态，其联机日志循环覆盖使用，这意味着如果数据库需要进行介质恢复应用相关归档，
又由于非归档导致归档文件不存在，那么此时数据库只能执行基于取消的恢复，回退整个数据库到上一次全备份状态。
或者修改数据文件头部信息，来规避缺失归档。但不管怎么样都会丢失数据。

(4)归档模式丢失非关键数据文件
如果丢失某个数据文件，且该文件不属于system或undo表空间，则可以还原并恢复缺少的数据文件。。。。
已经打开归档模式：
SQL> archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /u02/arch
Oldest online log sequence 47
Next log sequence to archive 49
Current log sequence 49

scott用户登录，创建一张表：
create table test as select * from dept;
select table_name,tablespace_name from dba_tables where table_name='TEST' and owner='SCOTT';

SQL> select table_name,tablespace_name from dba_tables where table_name='TEST' and owner='SCOTT';

TABLE_NAME TABLESPACE_NAME
------------------------------ ------------------------------
TEST USERS

查看表空间和文件名对应关系：
col file_name for a50
col tablespace_name for a10
col file_id for a50

select file_name,tablespace_name,file_id from dba_data_files where tablespace_name='USERS';
FILE_NAME TABLESPACE FILE_ID
-------------------------------------------------- ---------- ----------
/u02/oracle/oradata/orcl/users01.dbf USERS ##########

删除users表空间对应的数据文件。
rm -rf /u02/oracle/oradata/orcl/users01.dbf

SQL> select * from test;
select * from test
*
ERROR at line 1:
ORA-01116: error in opening database file 4
ORA-01110: data file 4: '/u02/oracle/oradata/orcl/users01.dbf'
ORA-27041: unable to open file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3

利用热备份的数据 cp
[oracle@oracle250 ~]$ cat hotbackup.sh
sqlplus / as sysdba <<eof
!echo 'begin hot backup '
alter database begin backup;
!echo 'copy files'
!cp -v /u02/oracle/oradata/orcl/system01.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/sysaux01.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/undotbs01.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/users01.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/test01.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/rrr.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/tttt.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/tttt02.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/tttt03.dbf /home/oracle/hot_backup/
!cp -v /u02/oracle/oradata/orcl/temp01.dbf /home/oracle/hot_backup/

!echo 'end backup database'
alter database end backup;
exit
eof

sys用户先执行：
alter database datafile 4 offline;
执行copy命令：
cp /home/oracle/hot_backup/users01.dbf /u02/oracle/oradata/orcl/users01.dbf

alter database datafile 4 online;
SQL> alter database datafile 4 online;
alter database datafile 4 online
*
ERROR at line 1:
ORA-01113: file 4 needs media recovery
ORA-01110: data file 4: '/u02/oracle/oradata/orcl/users01.dbf'

继续执行命令：(对该文件单独恢复！！！)
recover datafile 4;

SQL> recover datafile 4;
ORA-00279: change 1443443 generated at 08/31/2017 23:21:10 needed for thread 1
ORA-00289: suggestion : /u02/arch/1_44_944544087.dbf
ORA-00280: change 1443443 for thread 1 is in sequence #44

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
auto
ORA-00279: change 1447568 generated at 09/01/2017 01:05:39 needed for thread 1
ORA-00289: suggestion : /u02/arch/1_45_944544087.dbf
ORA-00280: change 1447568 for thread 1 is in sequence #45

Log applied.
Media recovery complete.

执行online
SQL> alter database datafile 4 online;

Database altered.

继续查询test表；
SQL> select * from test;

DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON

test表已经恢复了。。。。。。。搞定。

(5)归档模式丢失系统关键数据文件
如果丢失system或者undo表空间。
处理步骤：
1、shutdown abort关闭实例
2、装卸数据库 (mount状态)
3、还原并恢复丢失的数据文件
4、打开数据库

案例1：假如丢失undo表空间(先备份数据库)
SQL> select name from v$datafile;
/u02/oracle/oradata/orcl/system01.dbf
/u02/oracle/oradata/orcl/sysaux01.dbf
/u02/oracle/oradata/orcl/undotbs01.dbf
/u02/oracle/oradata/orcl/users01.dbf
/u02/oracle/oradata/orcl/test01.dbf
/u02/oracle/oradata/orcl/rrr.dbf
/u02/oracle/oradata/orcl/tttt.dbf
/u02/oracle/oradata/orcl/tttt02.dbf
/u02/oracle/oradata/orcl/tttt03.dbf

rm -rf /u02/oracle/oradata/orcl/undotbs01.dbf

错误信息：
ORA-01110: data file 3: '/u02/oracle/oradata/orcl/undotbs01.dbf'
ORA-1157 signalled during: ALTER DATABASE OPEN...

SQL> shutdown abort
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area 2772574208 bytes
Fixed Size 2256472 bytes
Variable Size 771752360 bytes
Database Buffers 1979711488 bytes
Redo Buffers 18853888 bytes
Database mounted.
ORA-01157: cannot identify/lock data file 3 - see DBWR trace file
ORA-01110: data file 3: '/u02/oracle/oradata/orcl/undotbs01.dbf'

把之前热备份uodo表空间的数据cp到相关目录：
cp /home/oracle/hot_backup/undotbs01.dbf /u02/oracle/oradata/orcl/

根据上面错误信息恢复数据文件3：
SQL> recover datafile 3;
ORA-00279: change 1467926 generated at 09/09/2017 08:56:55 needed for thread 1
ORA-00289: suggestion : /u02/arch/1_50_944544087.dbf
ORA-00280: change 1467926 for thread 1 is in sequence #50

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
auto
ORA-00279: change 1475654 generated at 09/09/2017 14:00:58 needed for thread 1
ORA-00289: suggestion : /u02/arch/1_51_944544087.dbf
ORA-00280: change 1475654 for thread 1 is in sequence #51

Log applied.
Media recovery complete.

最后打开数据库：
SQL> alter database open;

Database altered.

搞定！！！！！！！！！！！！！

(6)归档模式下，用户误删除表(日志挖掘)
通过日志挖掘恢复表。注意：之后的操作都失效了。
1、确保归档模式、确保备份有效。
使用scott模拟误删除，删除emp表
SQL> conn scott/tiger;
Connected.
SQL> select * from tab;

TNAME TABTYPECLUSTERID
------------------------------ ------- ----------
BONUS TABLE
DEPT TABLE
EMP TABLE
SALGRADE TABLE
TEST TABLE

SQL> drop table emp purge;

Table dropped.

2、使用sys用户，日志挖掘，找到误操作准确的scn
conn / as sysdba

构造日志挖掘队列语句。
select 'exec dbms_logmnr.add_logfile('''||member||''')' from v$logfile;
SQL> select 'exec dbms_logmnr.add_logfile('''||member||''')' from v$logfile;

exec dbms_logmnr.add_logfile('/u02/oracle/oradata/orcl/redo03.log')
exec dbms_logmnr.add_logfile('/u02/oracle/oradata/orcl/redo02.log')
exec dbms_logmnr.add_logfile('/u02/oracle/oradata/orcl/redo01.log')

3、执行构造挖掘语句，把当前3个redo文件都添加到挖掘队列中去。
SQL> exec dbms_logmnr.add_logfile('/u02/oracle/oradata/orcl/redo02.log')

PL/SQL procedure successfully completed.

SQL> exec dbms_logmnr.add_logfile('/u02/oracle/oradata/orcl/redo01.log')

PL/SQL procedure successfully completed.

SQL> exec dbms_logmnr.add_logfile('/u02/oracle/oradata/orcl/redo03.log')

PL/SQL procedure successfully completed.

4、执行挖掘：
exec dbms_logmnr.start_logmnr();

SQL> exec dbms_logmnr.start_logmnr();

PL/SQL procedure successfully completed.

5、查询挖掘出来信息,找出误操作的scn
select scn,sql_redo from v$logmnr_contents where seg_name='EMP' and seg_owner='SCOTT' and sql_redo like 'drop table emp%';

SQL> select scn,sql_redo from v$logmnr_contents where seg_name='EMP' and seg_owner='SCOTT' and sql_red
o like 'drop table emp%';
SCN
----------
SQL_REDO
1440820
drop table emp purge;

6、停止数据库。
把热备份的数据文件cp到相关目录：

cp /home/oracle/hot_backup/*.dbf /u02/oracle/oradata/orcl/ (生产环境要备份好。)

启动数据库到mount状态
startup mount;

7、执行恢复，把数据库恢复到误操作的scn(1440820)的前一刻 1440819
recover database until change 1440819;

8、 resetlogs 方式打开数据库。
alter database open resetlogs;

SQL> shutdown abort;
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.

Total System Global Area 2772574208 bytes
Fixed Size 2256472 bytes
Variable Size 771752360 bytes
Database Buffers 1979711488 bytes
Redo Buffers 18853888 bytes
Database mounted.
SQL> recover database until change 1440819;
Media recovery complete.
SQL> alter database open resetlogs;

Database altered.

最后看emp表：
SQL> select count(*) from emp;

COUNT(*)
----------
14
emp表找到了。。搞定了。。。。(最后重新备份。)