1. 修改
SQL>ALTER SYSTEM SET db_recovery_file_dest_size=4g;
SQL>ALTER SYSTEM SET db_recovery_file_dest='/oradata/flash_recovery_area';
SQL> alter database flashback on ;
报错：
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.
Total System Global Area 1593832664 bytes
Fixed Size 9135320 bytes
Variable Size 1023410176 bytes
Database Buffers 553648128 bytes
Redo Buffers 7639040 bytes
Database mounted.
原因:开启FLASHBACK DATABASE数据库必为归档模式
SQL> alter database archivelog;
Database altered.
SQL> alter database open;
Database altered.
SQL> select flashback_on from v$database;
FLASHBACK_ON
NO
SQL> alter database flashback on ;
Database altered.