生产上要做灾备系统的应急切换演练，灾备端是由OGG搭建的。由于生产库都比较大10多T，不想演练后重新初始化灾备库，生产库版本为10.2.0.4，于是想到10g的新特性flashback database。演练开始前记录一个还原点，演练结束后闪回到这个还原点，重新同步ogg即可。
测试闪加数据库。
一、开启FLASHBACK DATABASE
数据库版本：10.2.0.4
启用FLASHBACK DATABASE数据库必须为ARCHIVELOG模式，还需要有一个闪回恢复区用于存储闪回日志，RAC中闪回恢复区必须在集群文件系统或ASM中。
--数据库已开启归档，但还未启用FLASHBACK SQL> select flashback_on,log_mode from v$database; FLASHBACK_ON LOG_MODE ------------------------------------------------------ ------------------------------------ NO ARCHIVELOG --调整参数 SQL> alter system set db_recovery_file_dest_size=3G scope=spfile; System altered. SQL> alter system set db_recovery_file_dest=‘/u01/app/oracle/flashback_area/‘ scope=spfile; System altered. SQL> alter system set db_flashback_retention_target=2880 scope=spfile; System altered. --关闭数据库 SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. --启动到mount状态，开启FLASHBACK SQL> startup mount; ORACLE instance started. Total System Global Area 599785472 bytes Fixed Size 2085776 bytes Variable Size 192941168 bytes Database Buffers 398458880 bytes Redo Buffers 6299648 bytes Database mounted. SQL> alter database flashback on; Database altered. --启动数据库 SQL> alter database open; Database altered. --查看新状态 SQL> select flashback_on,log_mode from v$database; FLASHBACK_ON LOG_MODE ------------------------------------------------------ ------------------------------------ YES ARCHIVELOG
官方文档：http://docs.oracle.com/cd/B19306_01/backup.102/b14192/rpfbdb003.htm#sthref509
db_recovery_file_dest_size参数表示闪回恢复区的大小
db_recovery_file_dest参数表示闪回恢复区目录
db_flashback_retention_target表是闪回日志保留的时间，单位为分，默认1440(1天)
查看闪回恢复区里已生成闪回日志
[oracle@rhel5 flashback_area]$ cd /u01/app/oracle/flashback_area/MYDB/flashback/ [oracle@rhel5 flashback]$ ls -l total 8020 -rw-r----- 1 oracle oinstall 8200192 Jan 9 14:48 o1_mf_d76cxc1r_.flb
二、创建测试表
SQL> conn zx/zx Connected. SQL> create table flash_t as select * from all_tables; Table created. SQL> insert into flash_t select * from flash_t; 1559 rows created. SQL> / 3118 rows created. SQL> commit; Commit complete. SQL> select count(*) from flash_t; COUNT(*) ---------- 6236
三、查看数据库可以闪回的时间点
SQL> select * from V$FLASHBACK_DATABASE_LOG; OLDEST_FLASHBACK_SCN OLDEST_FLASHBACK_ RETENTION_TARGET FLASHBACK_SIZE ESTIMATED_FLASHBACK_SIZE -------------------- ----------------- ---------------- -------------- ------------------------ 7762668 20170109 14:37:32 2880 14467072 590954496
四、测试闪回数据库到一个时间点
--记录当前SCN用于闪回数据库 SQL> SELECT CURRENT_SCN FROM V$DATABASE; CURRENT_SCN ----------- 7765990 --删除测试表 SQL> conn / as sysdba Connected. SQL> select count(*) from zx.flash_t; COUNT(*) ---------- 6236 SQL> drop table zx.flash_t; Table dropped. SQL> select count(*) from zx.flash_t; select count(*) from zx.flash_t * ERROR at line 1: ORA-00942: table or view does not exist --闪回数据库 SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SQL> startup mount; ORACLE instance started. Total System Global Area 599785472 bytes Fixed Size 2085776 bytes Variable Size 192941168 bytes Database Buffers 398458880 bytes Redo Buffers 6299648 bytes Database mounted. --执行闪回 SQL> flashback database to scn 7765990; Flashback complete. --以resetlogs方式打开数据库 SQL> alter database open resetlogs; --可以使用alter database open read only打开数据库查看闪回后数据库的状态，如果闪回的不理想，重启到mount模式重新做flashback database Database altered. --验证测试表得到恢复 SQL> select count(*) from zx.flash_t; COUNT(*) ---------- 6236
闪回还可以指定时间或还原点
FLASHBACK DATABASE TO RESTORE POINT BEFORE_CHANGES;
FLASHBACK DATABASE TO TIME "TO_DATE(‘09/20/00‘,‘MM/DD/YY‘)";官方文档：http://docs.oracle.com/cd/B19306_01/backup.102/b14192/flashptr005.htm#BGBDCAFA
本文出自 “DBA Fighting!” 博客，请务必保留此出处http://hbxztc.blog.51cto.com/1587495/1890433
Oracle10g 闪回数据库 (Flashback Database)
原文地址：http://hbxztc.blog.51cto.com/1587495/1890433
