一、启用FLASHBACK
1、更改参数（在6节点执行如下脚本）
shutdown immediate;
startup mount;
alter system set db_recovery_file_dest_size=4G scope=both;
alter system set db_recovery_file_dest='/home/oracle/archlog' scope=both;
alter database flashback on;
alter database open;
2、确认
是否启用闪回
select FLASHBACK_ON from v$database;
闪回恢复区的内容
select file_type from v$flash_recovery_area_usage;
其他参数
show parameter DB_FLASHBACK_RETENTION_TARGET；
show parameter DB_RECOVERY_FILE_DEST_SIZE；
show parameter DB_RECOVERY_FILE_DEST；
3、记录脚本执行前SYSDATE
select to_char(sysdate, 'yyyy-mm-dd hh24:mi:ss') from dual;
4、表启用ROW MOVEMENT
ALTER TABLE INDUSTRY testflashback ROW MOVEMENT;
5、测试闪回（testflashback表）
select Count(*) from testflashback t;
COUNT(*)
5
delete from testflashback;
commit;
flashback table testflashback to timestamp to_date('2012-11-30 22:00:00','yyyy-mm-dd hh24:mi:ss');
select Count(*) from testflashback t;
COUNT(*)
二、关闭FLASHBACK
shutdown immediate;
startup mount;
alter database flashback off;
alter database open;
alter system set db_recovery_file_dest='' scope=both;
