OCP考题解析_043: flashback logs
OCP考题解析_043: flashback logs
为了实现闪回数据库，Oracle需要记录数据块的before image到一种新的日志中
这种日志被命名为flashback database logs闪回日志、闪回日志总是被循环复用，连续写出 www.zzzyk.com
在一个实例中当一个数据块首次被修改时，前台进程会将该数据块的before image拷贝到位于shared pool中的flashback log buffer中
RVWR进程定期地将flashback log buffer中的记录刷新到磁盘上
在DBWR进程可以写出相关脏块到磁盘之前，DBWR必须保证该buffer header相关FBA(Flashback Byte Address)的flashback log buffer已经写出到闪回日志
这被称作 "先写闪回日志" 机制 www.zzzyk.com
OCP考题：
[sql]
12. You are working on an Oracle Database 10g database. You enabled t
he Flashback Database feature. Which two statements regarding flashba
ck logs are true? (Choose two.)
A. Flashback logs are not archived.
B. Flashback logs are maintained in redo log files.
C. Flashback logs are maintained in the Flash Recovery Area.
D. Flashback logs are used to maintain Flashback Database related errors.
E. Flashback logs need to be cleared manually after you disable Flashback Database.
Answer: A, C
