(7) Maintaining Redo Log Files

• SQL> select * from v$log  (status: current/active/inactive/unused)

  SQL> select * from v$logfile (status: blank(in use)/stale(incomplete)/delete)

• Force log switch and CKPT
  SQL> alter system checkpoint
  SQL> alter system switch logfile
  FAST_START_MTTR_TARGET  (MTTR: meantime to recovery) (9i)  包含下面参数
  FAST_START_IO_TARGET  (8i)
  LOG_CHECKPOINT_INTERVAL
  LOG_CHECKPOINT_TIMEOUT
• Adding (drop) Online Redo Log Groups
  SQL> alter database add logfile group 6 ('xxx1','xxx2') size 1m;
  SQL> alter database drop logfile group 6;
  不能删除：当前日志组，活动日志组，没有归档的日志组
• Adding Online Redo Log Members
  SQL> alter database add logfile member 'xxx1' to group 6;
  SQL> alter database drop logfile member 'xxx1';
  不能删除：最后一个
• Clearing, Renaming and Relocation Online Redo Log
  SQL> alter database clear logfile 'xxx'   (reinit)
  SQL> alter database clear unarchived logfile 'xxx'   (reinit)       need fullbackup database

  SQL> alter database rename file 'xxx' to 'xxx1'

• Archived Redo Log File (Recovery and online backup)
  SQL> shutdown immediate
  SQL> startup mount
  SQL> alter database archivelog/noarchivelog;  切换日志模式
  SQL> alter database open;
  database full backup
  SQL> archive log list
  SQL> select * from v$archived_log;   
  SQL> alter system set log_archive_start=TRUE scope=spfile; 自动存档
• LOG　Minor
  (1) set directory  (UTL_FILE_DIR)
  (2) create file
        dbms_logmnr_d.build('aaa.ora','D:\oracle\admin\orcl9i\cdump');
  (3) add/remove log file
        dbms_logmnr.add_logfile(remove_logfile)('D:\oracle\oradata\orcl9i\REDO02.LOG',dbms_logmnr.new);
  (4) start logmnr
        dbms_logmnr.start_logmnr(dictfilename=>'D:\oracle\admin\orcl9i\cdump\aaa.ora');
  (5) select * from v$logmnr_contents (sql_redo/sql_undo)