V$LOGFILE.STATUS 和V$LOG.STATUS字段值的含义

1.V$LOGFILE.STATUS
   (http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/dynviews_1152.htm#sthref3730)
  类型：VARCHAR2(7)
  Status of the log member:
  1.INVALID - File is inaccessible(文件不可访问)
  2.STALE - File's contents are incomplete(表明该文件内容不完全，例如正在添加一个日志文件成员)
   If the redo log file group member has never been used,
   either due to a new redo log file group or a repaired member,
   the value of STATUS is STALE until the log file member is used
   to record redo information.
  3.DELETED - File is no longer used(该文件已不再使用)
  4.null - File is in use(文件正在使用中)
 
1.V$LOG.STATUS
  (http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/dynviews_1150.htm#sthref3726)
  类型：VARCHAR2(16)
  Log status:
 
  UNUSED - Online redo log has never been written to. This is the state of a redo
                   log that was just added, or just after a RESETLOGS, when it is not the
                   current redo log.
                   (表明从未对联机重做日志组进行写入，这种状态的日志文件要么而是刚增加的，
                   要么是当日志不是current redo log时RESETLOGS操作后的状态)
  CURRENT - Current redo log. This implies that the redo log is active. The redo log
                    could be open or closed.
                    (当前的联机重做日志组，这意味着该联机重做日志组是活动的)
  ACTIVE - Log is active but is not the current log. It is needed for crash recovery. It
                 may be in use for block recovery. It may or may not be archived.
                (联机重做日志组是活动的，但是并非当前联机重做日志组，崩溃恢复需要该状态
                 的日志，它可能用于块恢复，它可能已经归档也可能未归档)

  CLEARING - Log is being re-created as an empty log after an ALTER DATABASE
                     CLEAR LOGFILE statement. After the log is cleared, the status changes
                     to UNUSED.
                     (表明在ALTER DATABASE CLEAR LOGFILE 命令后正在将该日志重建为一个
                     空日志，日志清除后其状态更改为UNUSED。)

  CLEARING_CURRENT - Current log is being cleared of a closed thread. The log can
                                      stay in this status if there is some failure in the switch such
                                      as an I/O error writing the new log header.
                      （表明正在清除当前日志文件中的已关闭线程，如果切换时发生某些故障，
                         如写入新日志标题时的I/O错误，则该日志可以停留在该状态。）

  INACTIVE - Log is no longer needed for instance recovery. It may be in use for
                    media recovery. It might or might not be archived.
                    （表明例程恢复不再需要联机重做日志组，它可能已经归档也可能未归档。）