处理redo损坏

*Loss of online redo:

   1.Current 

      o When database closed normally :

          RECOVER DATABASE UNTIL CANCEL; / CANCEL

          ALTER DATABASE OPEN RESETLOGS; (Open resetlogs recreates log files)

      o When database was shutdown abnormally :

           restore backup and point in time recovery

            (eg RECOVER DATABASE UNTIL CANCEL and cancel when prev log applied)

        o No backup: _allow_resetlogs_corruption

                       RECOVER DATABASE USING BACKUP CONTROLFILE UNTIL CANCEL

                       *Rebuild essential*

                       ALTER DATABASE OPEN RESETLOGS;

   2.Non-Current

      o Add member, drop member