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FLASHBACK TABLE

描述

用于从回收站中恢复被删除的TABLE。

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。

OceanBase(admin@test)> 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

解释

object_name

指定要恢复的object名称或表名,只有在表所在的database中才能执行。恢复TABLE时,也会将和TABLE相关的INDEX也恢复出来。

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。
OceanBase(admin@test)> create table t(id int primary key, k int);
Query OK, 0 rows affected (0.04 sec)

OceanBase(admin@test)> insert into t values(1,1);
Query OK, 1 row affected (0.00 sec)

OceanBase(admin@test)> select * from t;
+----+------+
| id | k    |
+----+------+
|  1 |    1 |
+----+------+
1 row in set (0.00 sec)

OceanBase(admin@test)> drop table t;
Query OK, 0 rows affected (0.01 sec)

OceanBase(admin@test)> select * from t;
ERROR 1146 (42S02): Table 'test.t' does not exist
OceanBase(admin@test)> show recyclebin;
+--------------------------------+---------------+-------+----------------------------+
| OBJECT_NAME                    | ORIGINAL_NAME | TYPE  | CREATETIME                 |
+--------------------------------+---------------+-------+----------------------------+
| __recycle_$_1_1597028971700936 | t             | TABLE | 2020-08-10 11:09:31.701033 |
+--------------------------------+---------------+-------+----------------------------+
1 row in set (0.00 sec)

OceanBase(admin@test)> flashback table t to before drop;
Query OK, 0 rows affected (0.01 sec)

OceanBase(admin@test)> select * from t;
+----+------+
| id | k    |
+----+------+
|  1 |    1 |
+----+------+
1 row in set (0.00 sec)