1.修改闪回区大小，路径，保留时间

SQL> show parameter db_recovery_file_dest
SQL> show parameter db_flashback_retention_target

SQL> alter system set db_recovery_file_dest_size=20G scope=both;

System altered.

SQL> alter system set db_recovery_file_dest='/arch/flashback' scope=both;

System altered.

SQL> alter system set db_flashback_retention_target=4320 scope=both;   --单位分钟 4320=3天

System altered.

2.开启数据库闪回，需要停库启动到mount

SQL> select FLASHBACK_ON from v$database;

FLASHBACK_ON
------------------
NO

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.
Total System Global Area  584568832 bytes
Fixed Size                  2255432 bytes
Variable Size             226493880 bytes
Database Buffers          348127232 bytes
Redo Buffers                7692288 bytes
Database mounted.

SQL> alter database flashback on;

Database altered.

SQL> alter database open;

Database altered.

3.创建闪回点

SQL> select FLASHBACK_ON from v$database;

FLASHBACK_ON
------------------
YES

SQL> create restore point BEFORE_UPDATE guarantee flashback database;

Restore point created.

SQL> set line 200 pages 1000
SQL> col time for a35
SQL> col RESTORE_POINT_TIME for a30
SQL> col NAME for a30
SQL> select * from v$restore_point;

       SCN DATABASE_INCARNATION# GUA STORAGE_SIZE TIME                                RESTORE_POINT_TIME             PRE NAME
---------- --------------------- --- ------------ ----------------------------------- ------------------------------ --- ------------------------------
   1117669                     2 YES     52428800 23-SEP-22 08.18.37.000000000 PM                                    YES BEFORE_UPDATE

4.删除闪回点，关闭闪回，可以在线执行

SQL> drop restore point before_update;

Restore point dropped.

SQL> select * from v$restore_point;

no rows selected

SQL> alter database flashback off;

Database altered.

SQL> select FLASHBACK_ON from v$database;

FLASHBACK_ON
------------------
NO

5.执行闪回数据库命令

SQL> startup mount
ORACLE instance started.
Database mounted.

SQL>  select * from v$restore_point;

       SCN DATABASE_INCARNATION# GUA STORAGE_SIZE TIME                                RESTORE_POINT_TIME             PRE NAME
---------- --------------------- --- ------------ ----------------------------------- ------------------------------ --- ------------------------------
   1117848                     2 YES     52428800 23-SEP-22 08.20.59.000000000 PM                                    YES BEFORE_UPDATE

SQL> flashback database to restore point BEFORE_UPDATE;

Flashback complete.

SQL> alter database open resetlogs;

Database altered.

SQL> drop restore point BEFORE_UPDATE;

Restore point dropped.

SQL>  alter database flashback off;

Database altered.