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FLASHBACK TABLE BEFORE DROP

描述

用于从回收站中恢复被删除的表。

前置条件

回收站需要处于开启状态,可以通过SHOW VARIABLES LIKE 'recyclebin';来查看回收站是否开启。

obclient>SHOW VARIABLES LIKE 'recyclebin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| recyclebin    | ON    |
+---------------+-------+
1 row in set (0.00 sec)

如果回收站处于关闭状态,可以通过SET RECYCLEBIN = ON;来开启。回收站中的表没有被实际删除,仍然会占用资源,如果需要彻底删除,可以执行PURGE RECYCLEBIN;

格式

 FLASHBACK TABLE object_name TO BEFORE DROP [RENAME to db_name.table_name];

参数解释

参数

描述

object_name

指定要恢复的对象名称或表名,只有在表所在的数据库中才能执行。恢复表时,也会同步恢复和表相关的索引。

RENAME to

修改表名和表所属的库。

示例

  • 从回收站中恢复被删除的表 t。

obclient>CREATE TABLE t(id INT PRIMARY KEY, k INT);
Query OK, 0 rows affected (0.04 sec)

obclient>INSERT INTO t VALUES(1,1);
Query OK, 1 row affected (0.00 sec)

obclient>SELECT * FROM t;
+----+------+
| id | k    |
+----+------+
|  1 |    1 |
+----+------+
1 row in set (0.00 sec)

obclient>DROP TABLE t;
Query OK, 0 rows affected (0.01 sec)

obclient>SELECT * FROM t;
ORA-00942: table or view 'SYS.T' does not exist

obclient>SHOW RECYCLEBIN;
+--------------------------------+---------------+-------+----------------------------+
| OBJECT_NAME                    | ORIGINAL_NAME | TYPE  | CREATETIME                 |
+--------------------------------+---------------+-------+----------------------------+
| RECYCLE_$_2_1616038871797032 | T             | TABLE | 18-MAR-21 11.41.11.797691 AM|
+--------------------------------+---------------+-------+----------------------------+
1 row in set (0.00 sec)

obclient>FLASHBACK TABLE t TO BEFORE DROP;
Query OK, 0 rows affected (0.01 sec)

obclient>SELECT * FROM t;
+----+------+
| id | k    |
+----+------+
|  1 |    1 |
+----+------+
1 row in set (0.00 sec)