归档文件丢失，且主库增加了几个数据文件，如果前滚备库？

备库
RECOVER MANAGED STANDBY DATABASE CANCEL;
select min(s) min_scn from(SELECT CURRENT_SCN s FROM V$DATABASE
union select min(checkpoint_change#) from v$datafile_header);

主库识别这些新增的文件
SELECT FILE#, NAME FROM V$DATAFILE WHERE CREATION_CHANGE# > min_scn;
backup datafile 6,7,8 format '/tmp/ForStandby_%U' tag 'FORSTANDBY';
backup incremental from SCN 3162298 database format '/tmp/ForStandby_%U' tag 'FORSTANDBY';
backup current controlfile for standby format '/tmp/ForStandbyCTRL.bck';
scp /tmp/ForStandby* 备库:/tmp

备库
shutdown immediate;
startup nomount;
restore standby controlfile from '/tmp/ForStandbyCTRL.bck';
alter database mount;
CATALOG START WITH '/tmp/ForStandby';

run
{
set newname for datafile 6 to '+DISKGROUP';
set newname for datafile 7 to '+DISKGROUP';
set newname for datafile 8 to '+DISKGROUP';
restore datafile 6,7,8;
}

CATALOG START WITH '备库文件位置'; --例如：+DATA/orcldg/datafile/
SWITCH DATABASE TO COPY;
RECOVER DATABASE NOREDO;

ALTER DATABASE FLASHBACK OFF; --根据需要
ALTER DATABASE FLASHBACK ON;

ALTER DATABASE CLEAR LOGFILE GROUP 1;
ALTER DATABASE CLEAR LOGFILE GROUP 2;
ALTER DATABASE CLEAR LOGFILE GROUP 3;
RECOVER MANAGED STANDBY DATABASE DISCONNECT;

参考：
将数据文件添加到主数据库时使用 RMAN 增量备份前滚备用数据库的步骤（文档 ID 1531031.1）