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4.4.2 使用REPORT命令
与LIST命令不同，REPORT命令更详细地分析恢复目录中的信息，如需要更多地备份哪些文件，以便满足已经确定下来的保留策略的要求。下例将保留策略更改为4个副本，然后查询恢复目录以了解哪些数据文件并没有4个副本：
RMAN> configure retention policy to redundancy 4;
old RMAN configuration parameters:
CONFIGURE RETENTION POLICY TO REDUNDANCY 2;
new RMAN configuration parameters:
CONFIGURE RETENTION POLICY TO REDUNDANCY 4;
new RMAN configuration parameters are successfully stored
starting full resync of recovery catalog
full resync complete
RMAN> report need backup;
RMAN retention policy will be applied to the command
RMAN retention policy is set to redundancy 4
Report of files with less than 4 redundant backups
File #bkps Name
---- ----- -----------------------------------------------------
1 2 +DATA/RPT12C/DATAFILE/system.258.826650799
2 2 +DATA/RPT12C/DATAFILE/example.266.826650883
3 2 +DATA/RPT12C/DATAFILE/sysaux.257.826650753
4 2 +DATA/RPT12C/DATAFILE/undotbs1.260.826650845
5 3 +DATA/RPT12C/DATAFILE/users.269.826931347
6 3 +DATA/RPT12C/DATAFILE/users.259.826650843
7 2 +DATA/RPT12C/DATAFILE/undotbs1.270.826931347
. . .
96 2 /u02/oradata/xport.dbf
97 2 +DATA/RPT12C/DATAFILE/users9.404.832157465
98 2 +DATA/RPT12C/DATAFILE/users9.405.832159845
99 2 +DATA/RPT12C/DATAFILE/users4.407.834660445
100 2 +DATA/RPT12C/DATAFILE/users5.408.834661423
RMAN>
从报告中可以看到，USERS和SYSAUX表空间中的数据文件具有足够多的备份副本，可以满足保留策略的需要。
下面这个REPORT命令查找2013年8月30日的数据文件。
report schema at time='30-aug-2013';