看了Oracle
g的闪回数据库特性
书上说不能完成删除一个表空间并用resetlogs恢复
其实这也就是说如果改变了数据库的结构
是不能闪回的
只能闪回逻辑修改
但我还是做了一个实验
我删除了一个表空间再用数据库闪回发现不能打开数据库打开数据库的时候提示datafile 这个文件offline如果resetlogs就会丢失这个文件于是我就用RMAN进行恢复也就是要恢复到一个以前的时间用的是UNTIL TIME这个语法但在RESTORE就出错了告诉不能恢复控制文件在那个时间点确实没有备份控制文件但数据文件已经全部恢复了其实就是控制文件所记录的SCN与数据文件的SCN不一致数据库不能打开也就是控制文件比数据文件新我想到两个办法一个是重建控制文件用resetlogs选项一个是再往前面恢复恢复一个在这之前的控制文件我RMAN的controlfile autoback为on控制文件都有备份我采取了第二种办法
第一种重建控制文件用resetlogs选项新的控制文件的SCN是从数据文件中读取再recover database until cancel
第二种办法还是一个跨resetlogs时间点恢复因为昨天我做实验曾今用resetlogs打开过数据库所以我在恢复控制文件后还RESET DATABASE to incarnation n进行对应物的转换不然RMAN会报
RMAN UNTIL TIME is before RESETLOGSS time
Cause UNTIL TIME cannot be less than the database creation time or RESETLOGSS time
Action Check the UNTIL TIME If the database needs to be restored to an old incarnation use the
RESET DATABASE TO INCARNATION command
最后进行recover database 后数据成功恢复
记录下过程以后好参考
我还是该把中间结果保存下来
哦还有RMAN的controlfile autoback不仅在备份的时候会自动备份控制文件而且在数据库结构改变时也会自动备份这是有 SERVER PROCESS完成具体看
The control file is also automatically backed up after database structural changes such as adding a new tablespace altering the state of a tablespace or datafile （for example bringing it online） adding a new online redo log renaming a file adding a new redo thread and so on Losing this information would compromise your ability to recover the database
This backup is performed by the server process itself rather than one of the RMAN channels This type of autobackup unlike autobackups that occur after a successful backup is always created on disk You can useCONFIGURECONTROLFILEAUTOBACKUPFORDEVICETYPEDISKto set the location for this disk based control file autobackup Note that a failure of the automatic control file autobackup after a structural change never causes the associated structural change to fail For example if you add a datafile and if the resulting control file autobackup fails then the datafile addition is still successful
