如何使用 RMAN 增量备份恢复 data guard log gap（日志断档）
主库查询最小scn 信息：
sql> col current_scn for 999999999999999
sql> select current_scn from v$database;
select min(fhscn) from x$kcvfh;
select min(f.fhscn) from x$kcvfh f, v$datafile d
where f.hxfil =d.file#
and d.enabled != 'read only' ;
current_scn
----------------
12614205226673
min(fhscn)
----------------
12614205076072
min(f.fhscn)
----------------
12614205076072
+++++++++++++++++++++++++++++++++++++++++++++++=
1.----备库取消归档应用
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
2.----备库确定 lowest scn
col current_scn for 99999999999999
SELECT CURRENT_SCN FROM V$DATABASE;
select min(fhscn) from x$kcvfh;
select min(f.fhscn) from x$kcvfh f, v$datafile d
where f.hxfil =d.file#
and d.enabled != 'READ ONLY' ;
取上述查询中的最小值
SQL> col current_scn for 999999999999999999
SQL> SELECT CURRENT_SCN FROM V$DATABASE;
CURRENT_SCN
-------------------
12611050666604
SQL> select min(fhscn) from x$kcvfh;
MIN(FHSCN)
----------------
12611050666605
SQL> select min(f.fhscn) from x$kcvfh f, v$datafile d
where f.hxfil =d.file#
and d.enabled != 'READ ONLY' ; 2 3
MIN(F.FHSCN)
----------------
12611050666605
3.-----on primary db 端根据第2步中获取的最小scn 来进行增量备份
BACKUP INCREMENTAL FROM SCN 12611050666604 DATABASE FORMAT '/lixora/ForStandby_%U' tag 'FORSTANDBY';
4.-----拷贝备份到 备库
$scp ForStandby_07pqprm4_1_1 192.168.0.10:/tmp
5.----on standby db 在备库端注册备份片，注意用户属主，权限
RMAN> CATALOG START WITH '/lixora/ForStandby';
6.----执行恢复
RMAN> RECOVER DATABASE NOREDO;
7.-----on primary db 生成新的standby 控制文件
RMAN> BACKUP CURRENT CONTROLFILE FOR STANDBY FORMAT '/lixora/ForStandbyCTRL.bck';
8.----把主库端生成的standby 控制文件拷贝到备库，注意用户属主，权限
RMAN> BACKUP CURRENT CONTROLFILE FOR STANDBY FORMAT '/lixora/ForStandbyCTRL.bck';
scp /lixora/ForStandbyCTRL.bck 192.168.0.10:/tmp
9.------备份备库数据文件信息，用于在恢复新的standby 控制文件后比对
spool datafile_names_step8.txt
set lines 200
col name format a60
select file#, name from v$datafile order by file# ;
spool off
10.------on standby Db 恢复新的standby 控制文件
RMAN> SHUTDOWN IMMEDIATE ;
RMAN> STARTUP NOMOUNT;
RMAN> RESTORE STANDBY CONTROLFILE FROM '/tmp/ForStandbyCTRL.bck';
11.-----更新控制文件中的数据文件信息
使新的standby 控制文件生效
RMAN> SHUTDOWN;
RMAN> STARTUP MOUNT;
CATALOG START WITH '+DATA/zhglptdg/datafile/';
12.------on primary db。确保在备库发生日志gap 后，主库没有添加过新的数据文件。
SELECT FILE#, NAME FROM V$DATAFILE WHERE CREATION_CHANGE# > 12611050666604；
如果有记录，，则不能进行witch 操作，可以参考一下文档来恢复：
Note 1531031.1 Steps to perform for Rolling forward a standby database using RMAN incremental backup when datafile is added to primary
13.-----重命名数据文件
RMAN> SWITCH DATABASE TO COPY;
14.-----再次确认在恢复增量备份片后主库和备库scn 差距没有太大
SQL> col current_scn for 99999999999999
SELECT CURRENT_SCN FROM V$DATABASE;
select min(fhscn) from x$kcvfh;
select min(f.fhscn) from x$kcvfh f, v$datafile d
where f.hxfil =d.file#
and d.enabled != 'READ ONLY' ;
CURRENT_SCN
---------------
12614205662375
MIN(FHSCN)
----------------
12614205076072
MIN(F.FHSCN)
----------------
12614205076072
15.------ On standby database, 清理standby 日志组
select * from v$standby_log;
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 1;
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 2;
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 3;
16.------启动redo data apply
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT;
如果遇到一些由于设置 nologgling 而导致部分数据丢失，可以安装下述方法来进行恢复
To resolve NOLOGGING operations only, see Note 958181.1.
In addition to this information, see the online documentation:
10.2: #CIHIAADC
11.1: #SBYDB00759
11.2: #CIHIAADC
后记
如果要启用实时应用，需要在备库添加standby redo log，大小应和主库一样，且比主库多一组；
