ITPub博客

首页 > Linux操作系统 > Linux操作系统 > Question About RBA (Redo Block Address) [ID 759966.1]

Question About RBA (Redo Block Address) [ID 759966.1]

原创 Linux操作系统 作者:spider0283 时间:2012-04-24 15:53:57 0 删除 编辑

In this Document
  Goal
  Solution


This document is being delivered to you via Oracle Support's Rapid Visibility (RaV) process, and therefore has not been subject to an independent technical review.

Applies to:

Oracle Server - Enterprise Edition - Version: 10.2.0.3
Information in this document applies to any platform.

Goal

1. What is RBA? Can you explain it in relation to a transaction and commit scn?How can I find out
which RBAs exist in a archive log/redo log? 3. For example:
Completed checkpoint up to RBA [0x19.2.10], SCN: 5586949

Solution

A "Redo Block Address" (RBA) describes a physical location within a redo log file. An RBA consists
of the following:

Log sequence number
Block number within log file
Byte offset within block

The structure of the redo block address is given below :
1 - The number of the redo log.
[4 bytes]

2 - The block offset from the beginning of the redo log file.
[4 bytes]

3 - The byte offset within the block.
[2 bytes]

So in this case, RBA [0x19.2.10] maps to Log squence 25, Block number 2 with byte offset 16.

As for the relation between RBA and SCN, you can see that RBA is actually a physical location
inside the redo log file while SCN is the system change number that is in fact a unit of time (a
timestamp) maintained by the database kernel which is used to order events.





Back to TopBack to Top

来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/38267/viewspace-722136/,如需转载,请注明出处,否则将追究法律责任。

请登录后发表评论 登录
全部评论

注册时间:2011-03-29

  • 博文量
    194
  • 访问量
    608293