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。

  1. obclient>SHOW VARIABLES LIKE 'recyclebin';
  2. +---------------+-------+
  3. | Variable_name | Value |
  4. +---------------+-------+
  5. | recyclebin | ON |
  6. +---------------+-------+
  7. 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

  1. 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。
  1. obclient>CREATE TABLE t(id INT PRIMARY KEY, k INT);
  2. Query OK, 0 rows affected (0.04 sec)
  3. obclient>INSERT INTO t VALUES(1,1);
  4. Query OK, 1 row affected (0.00 sec)
  5. obclient>SELECT * FROM t;
  6. +----+------+
  7. | id | k |
  8. +----+------+
  9. | 1 | 1 |
  10. +----+------+
  11. 1 row in set (0.00 sec)
  12. obclient>DROP TABLE t;
  13. Query OK, 0 rows affected (0.01 sec)
  14. obclient>SELECT * FROM t;
  15. ORA-00942: table or view 'SYS.T' does not exist
  16. obclient>SHOW RECYCLEBIN;
  17. +--------------------------------+---------------+-------+----------------------------+
  18. | OBJECT_NAME | ORIGINAL_NAME | TYPE | CREATETIME |
  19. +--------------------------------+---------------+-------+----------------------------+
  20. | RECYCLE_$_2_1616038871797032 | T | TABLE | 18-MAR-21 11.41.11.797691 AM|
  21. +--------------------------------+---------------+-------+----------------------------+
  22. 1 row in set (0.00 sec)
  23. obclient>FLASHBACK TABLE t TO BEFORE DROP;
  24. Query OK, 0 rows affected (0.01 sec)
  25. obclient>SELECT * FROM t;
  26. +----+------+
  27. | id | k |
  28. +----+------+
  29. | 1 | 1 |
  30. +----+------+
  31. 1 row in set (0.00 sec)