这篇文章看不怎么明白，有人能帮助大概翻译下吗？

小新

Redo Byte Address (RBA)
Recent entries in the redo thread of an Oracle instance are addressed using a 3-part redo byte address, or RBA. An RBA is comprised of
the log file sequence number (4 bytes)
the log file block number (4 bytes)
the byte offset into the block at which the redo record starts (2 bytes)
RBAs are not necessarily unique within their thread, because the log file sequence number may be reset to 1 in all threads if a database is opened with the RESETLOGS option.
RBAs are used in the following important ways.

With respect to a dirty block in the buffer cache, the low RBA is the address of the redo for the first change that was applied to the block since it was last clean, and the high RBA is the address of the redo for the most recent change to have been applied to the block.
Dirty buffers are maintained on the buffer cache checkpoint queues in low RBA order. The checkpoint RBA is the point up to which DBWn has written buffers from the checkpoint queues if incremental checkpointing is enabled -- otherwise it is the RBA of last full thread checkpoint. The checkpoint RBA is copied into the checkpoint progress record of the controlfile by the checkpoint heartbeat once every 3 seconds. Instance recovery, when needed, begins from the checkpoint RBA recorded in the controlfile. The target RBA is the point up to which DBWn should seek to advance the checkpoint RBA to satisfy instance recovery objectives.

The on-disk RBA is the point up to which LGWR has flushed the redo thread to the online log files. DBWn may not write a block for which the high RBA is beyond the on-disk RBA. Otherwise transaction recovery (rollback) would not be possible, because the redo needed to undo a change is always in the same redo record as the redo for the change itself.

The term sync RBA is sometimes used to refer to the point up to which LGWR is required to sync the thread. However, this is not a full RBA -- only a redo block number is used at this point.

The low and high RBAs for dirty buffers can be seen in X$BH. (There is also a recovery RBA which is used to record the progress of partial block recovery by PMON.) The incremental checkpoint RBA, the target RBA and the on-disk RBA can all be seen in X$TARGETRBA. The incremental checkpoint RBA and the on-disk RBA can also be seen in X$KCCCP. The full thread checkpoint RBA can be seen in X$KCCRT.

biti_rainy

首先要明白 oracle 怎么保障数据的不丢失和可恢复，从恢复的角度去理解

检查点、dbwr怎么工作的，和 lgwr 怎么配合的，再来读这个文章自然就明白了

文章，又如何仅仅是这字面的翻译，先读 oracle 体系结构中关于几个进程的原理和相互的配合再来读这个

小新

thanks ,biti

agdszfg

重做字节地址（央行）
最近条目的重做线程的一个Oracle实例是针对使用三部分重做字节地址，或央行。央行是一个组成
日志文件序列号（ 4字节）
日志文件的块数（ 4字节）
的字节偏移量块上的重做记录开始（ 2字节）
阿拉伯国家区域局不一定是唯一的，他们的线程，因为日志文件序列号可重置为1的所有线程如果数据库是打开的RESETLOGS选项。
阿拉伯国家区域局中使用下列重要途径。
对于一个肮脏块缓冲区高速缓存，低央行的地址重做第一变化，适用于该区块因为它是过去干净，和高央行的地址重做最近的改变已应用于块。
脏缓冲区保持对检查站队列缓存低央行秩序。该检查站是央行点的DBWn写缓冲器从检查站排队，如果增量检查点已启用-否则它是央行去年全螺纹检查站。该检查站央行复制到检查站进展记录controlfile的检查站
心跳每3秒钟。例如恢复，必要时，开始从检查站央行记录在controlfile 。央行的目标是点的DBWn应设法推动央行检查站，以满足个体回收目标。
磁碟央行是这点已刷新LGWR的重做线程的在线日志文件。 DBWn不得写块，而高央行超出了磁盘上的央行。否则交易复苏（回滚）将是不可能的，因为重做需要撤消改变总是在同一重做的重做记录的变化本身。
任期同步央行有时用以指的点而LGWR需要同步线程。然而，这不是一个充分央行-只有重做块号码是用在了这一点。
低及高阿拉伯国家区域局的肮脏缓冲器可以看出在X $波黑。 （还有一个复苏央行这是用来记录的进展，部分区块恢复PMON 。 ）的增量检查点央行，澳洲联储的目标和磁盘上的央行都可以看到在X $ TARGETRBA 。增量检查点央行和磁盘上的央行也可以看出在X $ KCCCP 。充分线程检查中可以看出央行在X $ KCCRT 。

venee_lee

好老的帖子。是大师的文章，原文是internals下 redo 的 章节Redo Byte Address (RBA)