redo log 的active和ina…

redo log 的active和inactive的区别

概况有以下几点：

1.redo的inactive和active状态跟是否完成归档没有关系

2.redo的active与dirty
buffer是有关联的，即：redo的active和inactive主要取决于相对应的脏块是否写入数据文件，如果相对应的脏块已经被DBWR写入数据文件，那么redo由active变为inactive。

3.在active状态下redo，可能已经完成了归档（仍在等待脏块的写入，所以还未变为inactive），也可能还没有完成归档。

4.在inactive状态下的redo，可能已经完成了归档，也可能还未完成归档。

5.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.

CURRENT - Current redo log. This implies that the redo log
is active. The redo log could be open or closed.

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.

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.

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.

INACTIVE - Log is no longer needed for instance recovery. It
may be in use for media recovery. It may or may not be
archived.

跟redo log 的active和inactive有关的OCP试题

Your production database is running in the ARCHIVELOG mode and the ARCn process is functional.

You have two online redo log groups. Which three background processes would be involved when a log

switch happens? (Choose three.)

A.archival

B.log writer

C.database writer

D.system monitor

E.process monitor

F.change tracking writer

Answer: ABC

Because of hardware failure, you decided to drop a redo log member from the database.

Which condition should be met to drop a redo log file?

A.The redo log file should belong to an active group.

B.The redo log file should belong to an inactive group.

C.The redo log file should belong to the current group.

D.The redo log file can be dropped only if all the transactions are stopped.

E.Before a redo log file is dropped, it should be deleted from the operating system (OS).

Answer: B

关于redo log 的active和inactive的区别，我跟其他网友做了相关讨论，并整理为帖子，以便查阅，详情见：
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