V$FLASHBACK_DATABASE_LOG &&…

V$FLASHBACK_DATABASE_LOG 和 V$FLASHBACK_DATABASE_STAT

记录一下ORACE 10g 1Z0-043 中关于闪回的两个视图

SQL> col object_name for a30;

SQL>

SQL> select o.object_name, o.object_type

2 from
dba_objects o

3 where
o.object_name like 'V$FLASH%';

OBJECT_NAME

OBJECT_TYPE

------------------------------
-------------------

V$FLASHBACK_DATABASE_LOG
SYNONYM

V$FLASHBACK_DATABASE_LOGFILE
SYNONYM

V$FLASHBACK_DATABASE_STAT

SYNONYM

V$FLASHBACK_TXN_GRAPH
SYNONYM

V$FLASHBACK_TXN_MODS
SYNONYM

V$FLASH_RECOVERY_AREA_USAGE
SYNONYM

V$FLASHBACK_DATABASE_LOG
显示闪回数据的信息，用来评估当前负载下需要的闪回空间

v$flashback_database_log

Name
Description

------------------------------
--------------------------

OLDEST_FLASHBACK_SCN
Lowest system change number (SCN) in the flashback data, for any
incarnation

闪回数据最小的scn

OLDEST_FLASHBACK_TIME
Time of the lowest SCN in the flashback data, for any
incarnation

闪回数据最小的时间

RETENTION_TARGET Target
retention time (in minutes)

闪回保留时间

FLASHBACK_SIZE
Current size (in bytes) of the flashback
data

闪回数据大小

ESTIMATED_FLASHBACK_SIZE
Estimated size of flashback data needed for the current target
retention

评估满足当前闪回保留时间，需要的闪回空间的大小

V$FLASHBACK_DATABASE_STAT

显示数据库收集到的闪回信息

Name
Description

------------------------
--------------------------------

BEGIN_TIME
Beginning of the time interval

一段时间间隔的起始时间

END_TIME End
of the time interval

一段时间间隔的结束时间

FLASHBACK_DATA Number
of bytes of flashback data written during the
interval

一段时间内闪回数据的大小(bytes)

DB_DATA
Number of bytes of database data read and written during the
interval

一段时间内数据库读写大小(bytes)

REDO_DATA Number
of bytes of redo data written during the interval

一段时间内redo
数据的大小(bytes)

ESTIMATED_FLASHBACK_SIZE
Value of ESTIMATED_FLASHBACK_SIZE in V$FLASHBACK_DATABASE_LOG at
the

end of the time interval

一段时间间隔的结束时，评估需要闪回空间的大小

转自：http://blog.csdn.net/lwei_998/article/details/6125403

OCP试题

186. You executed the following query in your database:

FROM V$FLASHBACK_DATABASE_LOG;

What would you determine from the output?

A.the time when the last flashback operation in your database was performed

B.the time when the first flashback operation in your database was performed

C.a list of flashback operations performed in your database using SCN and time

D.the approximate time and the lowest system change number (SCN) to which you can flash back your

database

Answer: D

187. These are the details about V$FLASHBACK_DATABASE_STAT:

SQL> DESC V$FLASHBACK_DATABASE_STAT

Name Null? Type

­­­­­­­­­­­­­­­­­­­­­­­­­­-----
-------- ----------

BEGIN_TIME DATE

END_TIME DATE

FLASHBACK_DATA NUMBER

DB_DATA NUMBER

REDO_DATA NUMBER

ESTIMATED_FLASHBACK_SIZE NUMBER

Which two statements regarding the V$FLASHBACK_DATABASE_STAT view are true? (Choose two.)

A.BEGIN_TIME is the time at which Flashback logging is enabled.

B.END_TIME is the time at which the query is executed on the view.

C.REDO_DATA is the number of bytes of redo data written during the interval.

D.This view contains information about flashback data pertaining to the last 24 hours.

E.FLASHBACK_DATA is the amount of flashback data generated since the database was opened.

Answer: CD