闪回是oracle10g的最大新特性，之前整理过闪回的大部分内容，包括闪回数据库，闪回删除表，删除表，闪回版本查询等，本讲主要介绍保障闪回点和闪回相关数据字典和动态性能视图的查询
一:创建闪回保障点
[oracle@rhel6 ~]$ export ORACLE_SID=winorcl
[oracle@rhel6 ~]$ sqlplus /nolog
SQL*Plus: Release 10.2.0.1.0 - Production on Mon Jul 18 14:35:36 2011
Copyright (c) 1982, 2005, Oracle. All rights reserved.
SQL> conn /as sysdba
Connected
SQL> select flashback_on,name,log_mode from v$database;
FLASHBACK_ NAME LOG_MODE
---------- --------------------------- --------------
NO WINORCL ARCHIVELOG
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.
Total System Global Area 268435456 bytes
Fixed Size 2020056 bytes
Variable Size 130026792 bytes
Database Buffers 130023424 bytes
Redo Buffers 6365184 bytes
Database mounted.
SQL> alter database flashback on;
Database altered.
SQL> alter database open;
Database altered
[oracle@rhel6 ~]$ ps -ef |grep rvwr
oracle 25280 1 0 14:38 00:00:00 ora_rvwr_winorcl
SQL> create restore point important_change guarantee flashback database;
Restore point created.
SQL> show parameter flash;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_flashback_retention_target integer 4320
SQL> select scn,name,time,guarantee_flashback_database as gfb from v$restore_point;
SCN NAME TIME GFB
---------- ---------- -------------------- ---------
731367 IMPORTANT_ 18-JUL-11 02.43.28.0 YES
CHANGE 00000000 PM
二:查看相关动态性能视图
SQL> SELECT estimated_flashback_size,
2 flashback_size
3* FROM V$FLASHBACK_DATABASE_LOG；
ESTIMATED_FLASHBACK_SIZE FLASHBACK_SIZE
------------------------ --------------
117645312 8192000
SQL> SELECT oldest_flashback_scn,
2 oldest_flashback_time
3* FROM V$FLASHBACK_DATABASE_LOG；
OLDEST_FLASHBACK_SCN OLDEST_FLASHBACK_TI
-------------------- -------------------
731198 2011-07-18-14:38:56
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