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OceanBase 回收站 和 闪回删除（Flashback Drop） 操作示例

2023-07-04 17:29 1035 0 原创 OceanBase
作者： dave
本文链接：http://www.cndba.cn/dave/article/131404

1 回收站概述

回收站在原理上说就是一个数据字典表，放置用户删除的数据库对象信息。用户删除的对象被放入回收站后，其实仍然占据着物理空间，除非您手动进行清除（PURGE）或者对象定期被数据库系统删除。

在当前版本中，支持进入回收站的对象有索引、表、库和租户。由于当前仅 sys 租户可以删除租户，故 MySQL 用户租户和 Oracle 用户租户被删除后，只能进入 sys 租户的回收站中。

  1. sys 租户：支持管理的回收站对象包括数据库、表、索引及租户。
  2. MySQL 用户租户：支持管理的回收站对象包括数据库、表及索引。
  3. Oracle 用户租户：支持管理的回收站对象包括表和索引。

使用限制

  1. 直接删除索引，该索引不会进入回收站。删除表时，表上的索引会随主表一起进入回收站。
  2. FLASHBACK 数据库对象的顺序需要符合从属关系，即：Database > Table。
  3. 不支持直接恢复索引，恢复表会连同索引一并恢复。
  4. 不能对回收站对象做任何查询和 DML 操作，DDL 操作中也仅支持 Purge 和 Flashback 操作。
  5. 进入回收站的对象并不是直接删除，而是会继续占用存储空间。

2 开启/关闭回收站

在 OceanBase 数据库中，通过系统变量 recyclebin 来控制回收站的开启和关闭，默认回收站为关闭状态。

在 OB 4.1 版本中，开启回收站对性能基本没有影响了。

2.1 查看回收站状态

obclient [backup]> SHOW VARIABLES LIKE 'recyclebin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| recyclebin    | OFF   |
+---------------+-------+
1 row in set (0.001 sec)

recyclebin 是租户级参数，要在租户重修改，可以配置如下值：

  1. on 、1 或 true：表示开启回收站。
  2. off 、0 或 false：表示关闭回收站。

可以在两个级别设置：

http://www.cndba.cn/dave/article/131404

  1. Global ：整个租户内生效。
  2. Session ：对当前Session 生效。

2.2 开启回收站

连接到租户：

[dave@www.cndba.cn ~]$obclient -h192.168.1.21 -P2881 -uroot@backup -p'xxxxx' -Doceanbase -A
Welcome to the OceanBase.  Commands end with ; or /g.
Your OceanBase connection id is 3221747599
Server version: OceanBase_CE 4.1.0.0 (r101010022023051821-f7379b26f8cd11f026e06846043550f9e0d42ead) (Built May 18 2023 21:14:14)

Copyright (c) 2000, 2018, OceanBase and/or its affiliates. All rights reserved.

Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.

obclient [oceanbase]>

obclient [backup]> SET GLOBAL recyclebin = on;
Query OK, 0 rows affected (0.193 sec)

obclient [backup]> SET GLOBAL recyclebin = 1;
Query OK, 0 rows affected (0.002 sec)

obclient [backup]> SET GLOBAL recyclebin = true;
Query OK, 0 rows affected (0.002 sec)

obclient [oceanbase]>  SHOW VARIABLES LIKE 'recyclebin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| recyclebin    | ON    |
+---------------+-------+
1 row in set (0.002 sec)

2.3 关闭回收站

obclient [oceanbase]> SET GLOBAL recyclebin = off;
Query OK, 0 rows affected (0.126 sec)

obclient [oceanbase]> SET GLOBAL recyclebin = 0;
Query OK, 0 rows affected (0.002 sec)

obclient [oceanbase]> SET GLOBAL recyclebin = false;
Query OK, 0 rows affected (0.001 sec)

obclient [oceanbase]> SHOW VARIABLES LIKE 'recyclebin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| recyclebin    | ON    |
+---------------+-------+
1 row in set (0.000 sec)

obclient [oceanbase]> exit
Bye

重新登录生效：http://www.cndba.cn/dave/article/131404

[dave@www.cndba.cn ~]$obclient -h192.168.1.21 -P2881 -uroot@backup -p'xxxxx' -Doceanbase -A
Welcome to the OceanBase.  Commands end with ; or /g.
Your OceanBase connection id is 3221560590
Server version: OceanBase_CE 4.1.0.0 (r101010022023051821-f7379b26f8cd11f026e06846043550f9e0d42ead) (Built May 18 2023 21:14:14)

Copyright (c) 2000, 2018, OceanBase and/or its affiliates. All rights reserved.

Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.

obclient [oceanbase]> SHOW VARIABLES LIKE 'recyclebin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| recyclebin    | OFF   |
+---------------+-------+
1 row in set (0.000 sec)

obclient [oceanbase]>

3 查看回收站中对象

[dave@www.cndba.cn ~]$obclient -h192.168.1.21 -P2881 -uroot@backup -p'xxxxx' -Doceanbase -A
Welcome to the OceanBase.  Commands end with ; or /g.
Your OceanBase connection id is 3221525741
Server version: OceanBase_CE 4.1.0.0 (r101010022023051821-f7379b26f8cd11f026e06846043550f9e0d42ead) (Built May 18 2023 21:14:14)

Copyright (c) 2000, 2018, OceanBase and/or its affiliates. All rights reserved.

Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.

obclient [oceanbase]> use backup
Database changed
obclient [backup]> show tables;
+------------------+
| Tables_in_backup |
+------------------+
| bmsql_config     |
| bmsql_customer   |
| bmsql_district   |
| bmsql_history    |
| bmsql_item       |
| bmsql_new_order  |
| bmsql_oorder     |
| bmsql_order_line |
| bmsql_stock      |
| bmsql_warehouse  |
+------------------+
10 rows in set (0.001 sec)

obclient [backup]> drop table bmsql_config;
Query OK, 0 rows affected (0.924 sec)

obclient [backup]> SHOW RECYCLEBIN;
+--------------------------------+---------------+-------+----------------------------+
| OBJECT_NAME                    | ORIGINAL_NAME | TYPE  | CREATETIME                 |
+--------------------------------+---------------+-------+----------------------------+
| __recycle_$_1_1688449379272432 | bmsql_config  | TABLE | 2023-07-04 13:42:59.283804 |
+--------------------------------+---------------+-------+----------------------------+
1 row in set (0.005 sec)

obclient [backup]>

返回结果中的相关字段说明如下：

  1. OBJECT_NAME：表示该对象在回收站中的名称。
  2. ORIGINAL_NAME：表示原对象名。
  3. CREATETIME：表示该对象进入回收站的时间。
  4. TYPE：表示回收站对象所属的类型。其中：
  • 系统租户（sys 租户）支持 INDEX、TABLE、DATABASE 和 TENANT 四种类型。
  • MySQL 用户租户支持 INDEX、TABLE 和 DATABASE 三种类型。
  • Oracle 用户租户支持 INDEX 和 TABLE 两种类型。

4 恢复回收站对象

4.1 恢复表

sys 租户、 MySQL 用户租户和 Oracle 用户租户均可以从回收站中恢复表。恢复时可修改表的名称，但是不能与已有表重名，否则系统会报错。


[dave@www.cndba.cn ~]$obclient -h192.168.1.21 -P2881 -uroot@backup -p'xxxxx' -Doceanbase -A
Welcome to the OceanBase.  Commands end with ; or /g.
Your OceanBase connection id is 3221523401
Server version: OceanBase_CE 4.1.0.0 (r101010022023051821-f7379b26f8cd11f026e06846043550f9e0d42ead) (Built May 18 2023 21:14:14)

Copyright (c) 2000, 2018, OceanBase and/or its affiliates. All rights reserved.

Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.

obclient [oceanbase]> use backup;
Database changed
obclient [backup]> 

obclient [backup]> drop table bmsql_customer;
Query OK, 0 rows affected (0.611 sec)

查看回收站：

http://www.cndba.cn/dave/article/131404 

obclient [backup]> SHOW RECYCLEBIN;
+--------------------------------+----------------------------------+-------+----------------------------+
| OBJECT_NAME                    | ORIGINAL_NAME                    | TYPE  | CREATETIME                 |
+--------------------------------+----------------------------------+-------+----------------------------+
| __recycle_$_1_1688449379272432 | bmsql_config                     | TABLE | 2023-07-04 13:42:59.283804 |
| __recycle_$_1_1688458388028600 | __idx_501364_bmsql_customer_idx1 | INDEX | 2023-07-04 16:13:08.028826 |
| __recycle_$_1_1688458388060704 | bmsql_customer                   | TABLE | 2023-07-04 16:13:08.061344 |
+--------------------------------+----------------------------------+-------+----------------------------+
3 rows in set (0.002 sec)

从回收站中恢复表，恢复后的表名为进入回收站前的表名：http://www.cndba.cn/dave/article/131404

obclient [backup]> FLASHBACK TABLE __recycle_$_1_1688458388060704 to before drop;
Query OK, 0 rows affected (0.155 sec)

obclient [backup]> select count(1) from bmsql_customer;
+----------+
| count(1) |
+----------+
|  6000000 |
+----------+
1 row in set (0.026 sec)

obclient [backup]>

从回收站中恢复表并重命名：

obclient [backup]> SHOW RECYCLEBIN;
+--------------------------------+---------------+-------+----------------------------+
| OBJECT_NAME                    | ORIGINAL_NAME | TYPE  | CREATETIME                 |
+--------------------------------+---------------+-------+----------------------------+
| __recycle_$_1_1688449379272432 | bmsql_config  | TABLE | 2023-07-04 13:42:59.283804 |
+--------------------------------+---------------+-------+----------------------------+
1 row in set (0.002 sec)

obclient [backup]>  FLASHBACK TABLE __recycle_$_1_1688449379272432 to before drop rename to dave;
Query OK, 0 rows affected (0.133 sec)

obclient [backup]> select count(1) from dave;
+----------+
| count(1) |
+----------+
|        4 |
+----------+
1 row in set (0.089 sec)

从回收站中将表恢复到指定的数据库或 Schema 对象并重命名：

obclient [backup]> drop table dave;
Query OK, 0 rows affected (0.415 sec)

obclient [backup]> show recyclebin;
+--------------------------------+---------------+-------+----------------------------+
| OBJECT_NAME                    | ORIGINAL_NAME | TYPE  | CREATETIME                 |
+--------------------------------+---------------+-------+----------------------------+
| __recycle_$_1_1688458928714784 | dave          | TABLE | 2023-07-04 16:22:08.715401 |
+--------------------------------+---------------+-------+----------------------------+
1 row in set (0.002 sec)

obclient [backup]> FLASHBACK TABLE __recycle_$_1_1688458928714784 to before drop rename to ustc.dave;
Query OK, 0 rows affected (0.141 sec)

obclient [backup]> select count(1) from ustc.dave;
+----------+
| count(1) |
+----------+
|        4 |
+----------+
1 row in set (0.013 sec)

4.2 恢复数据库

sys 租户或 MySQL 用户租户可以从回收站中恢复数据库。恢复时可修改数据库名称，但不能与已有数据库重名，否则系统会报错。

http://www.cndba.cn/dave/article/131404

从回收站中恢复数据库，恢复后的数据库名为进入回收站前的名称：

obclient [backup]> drop database ustc;
Query OK, 1 row affected (0.408 sec)

obclient [backup]> show recyclebin;
+--------------------------------+---------------+----------+----------------------------+
| OBJECT_NAME                    | ORIGINAL_NAME | TYPE     | CREATETIME                 |
+--------------------------------+---------------+----------+----------------------------+
| __recycle_$_1_1688459423547168 | ustc          | DATABASE | 2023-07-04 16:30:23.546660 |
+--------------------------------+---------------+----------+----------------------------+
1 row in set (0.002 sec)

obclient [backup]> FLASHBACK DATABASE  __recycle_$_1_1688459423547168 to before drop;
Query OK, 0 rows affected (0.143 sec)

obclient [backup]> show recyclebin;
Empty set (0.002 sec)

从回收站中恢复数据库并重命名：http://www.cndba.cn/dave/article/131404

obclient [backup]>  drop database ustc;
Query OK, 1 row affected (0.409 sec)

obclient [backup]> show recyclebin;
+--------------------------------+---------------+----------+----------------------------+
| OBJECT_NAME                    | ORIGINAL_NAME | TYPE     | CREATETIME                 |
+--------------------------------+---------------+----------+----------------------------+
| __recycle_$_1_1688459584139248 | ustc          | DATABASE | 2023-07-04 16:33:04.138794 |
+--------------------------------+---------------+----------+----------------------------+
1 row in set (0.003 sec)

obclient [backup]>  FLASHBACK DATABASE  __recycle_$_1_1688459584139248 to before drop rename to dave;
Query OK, 0 rows affected (0.143 sec)

obclient [backup]> show recyclebin;
Empty set (0.002 sec)

4.3 恢复租户

由于当前仅 sys 租户可以删除租户，故仅 sys 租户可以将回收站中的租户恢复为正常租户。恢复时可修改租户名称，但不能与已有租户重名，否则系统会报错。

租户的恢复是依赖 SYS 租户的，我们之前测试都是针对单个租户进行回收站的启用和关闭。

所以在测试租户恢复之前，需要先启用 SYS 租户的回收站。 从实际使用来看，整租户的恢复应用场景较少。 这里仅做测试。

http://www.cndba.cn/dave/article/131404

4.3.1 开通 SYS 租户的回收站

[dave@www.cndba.cn ~]$obclient -h192.168.1.21 -P2881 -uroot -p'xxxxx' -Doceanbase -A
Welcome to the OceanBase.  Commands end with ; or /g.
Your OceanBase connection id is 3221625909
Server version: OceanBase_CE 4.1.0.0 (r101010022023051821-f7379b26f8cd11f026e06846043550f9e0d42ead) (Built May 18 2023 21:14:14)

Copyright (c) 2000, 2018, OceanBase and/or its affiliates. All rights reserved.

Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.

obclient [oceanbase]> show recyclebin;
Empty set (0.005 sec)

obclient [oceanbase]> SHOW VARIABLES LIKE 'recyclebin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| recyclebin    | OFF   |
+---------------+-------+
1 row in set (0.000 sec)

obclient [oceanbase]> SET GLOBAL recyclebin = on;
Query OK, 0 rows affected (0.124 sec)

obclient [oceanbase]> SHOW VARIABLES LIKE 'recyclebin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| recyclebin    | OFF   |
+---------------+-------+
1 row in set (0.000 sec)

obclient [oceanbase]> exit
Bye
[dave@www.cndba.cn ~]$obclient -h192.168.1.21 -P2881 -uroot -p'xxxxx' -Doceanbase -A
Welcome to the OceanBase.  Commands end with ; or /g.
Your OceanBase connection id is 3221570940
Server version: OceanBase_CE 4.1.0.0 (r101010022023051821-f7379b26f8cd11f026e06846043550f9e0d42ead) (Built May 18 2023 21:14:14)

Copyright (c) 2000, 2018, OceanBase and/or its affiliates. All rights reserved.

Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.

obclient [oceanbase]> SHOW VARIABLES LIKE 'recyclebin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| recyclebin    | ON    |
+---------------+-------+
1 row in set (0.000 sec)

obclient [oceanbase]>

4.3.2 恢复

将回收站中的租户恢复为正常租户，且恢复后的租户名为进入回收站前的租户名：

obclient [oceanbase]> show recyclebin;
Empty set (0.004 sec)

obclient [oceanbase]> drop tenant backup2;
Query OK, 0 rows affected (0.124 sec)

obclient [oceanbase]> show recyclebin;
+--------------------------------+---------------+--------+----------------------------+
| OBJECT_NAME                    | ORIGINAL_NAME | TYPE   | CREATETIME                 |
+--------------------------------+---------------+--------+----------------------------+
| __recycle_$_1_1688461891658032 | backup2       | TENANT | 2023-07-04 17:12:43.347386 |
+--------------------------------+---------------+--------+----------------------------+
1 row in set (0.004 sec)

obclient [oceanbase]> FLASHBACK TENANT __recycle_$_1_1688461891658032 to before drop;
Query OK, 0 rows affected (0.116 sec)

obclient [oceanbase]> show recyclebin;
Empty set (0.004 sec)

将回收站中的租户恢复为正常租户并重命名：

obclient [oceanbase]> drop tenant backup2;
Query OK, 0 rows affected (0.116 sec)

obclient [oceanbase]> show recyclebin;
+--------------------------------+---------------+--------+----------------------------+
| OBJECT_NAME                    | ORIGINAL_NAME | TYPE   | CREATETIME                 |
+--------------------------------+---------------+--------+----------------------------+
| __recycle_$_1_1688462003782944 | backup2       | TENANT | 2023-07-04 17:13:52.231967 |
+--------------------------------+---------------+--------+----------------------------+
1 row in set (0.005 sec)

obclient [oceanbase]> FLASHBACK TENANT __recycle_$_1_1688462003782944 to before drop rename to ustc;
Query OK, 0 rows affected (0.113 sec)

obclient [oceanbase]> select tenant_id,tenant_name,tenant_type,COMPATIBILITY_MODE,PRIMARY_ZONE from dba_ob_tenants;
+-----------+-------------+-------------+--------------------+-------------------+
| tenant_id | tenant_name | tenant_type | COMPATIBILITY_MODE | PRIMARY_ZONE      |
+-----------+-------------+-------------+--------------------+-------------------+
|         1 | sys         | SYS         | MYSQL              | RANDOM            |
|      1001 | META$1002   | META        | MYSQL              | RANDOM            |
|      1002 | ocp         | USER        | MYSQL              | RANDOM            |
|      1011 | META$1012   | META        | MYSQL              | RANDOM            |
|      1012 | tpcc_mysql  | USER        | MYSQL              | RANDOM            |
|      1013 | META$1014   | META        | MYSQL              | zone1,zone2,zone3 |
|      1014 | oms         | USER        | MYSQL              | zone1,zone2,zone3 |
|      1015 | META$1016   | META        | MYSQL              | RANDOM            |
|      1016 | backup      | USER        | MYSQL              | RANDOM            |
|      1019 | META$1020   | META        | MYSQL              | RANDOM            |
|      1020 | open_gpt    | USER        | MYSQL              | RANDOM            |
|      1021 | META$1022   | META        | MYSQL              | zone1,zone2,zone3 |
|      1022 | ustc        | USER        | MYSQL              | zone1,zone2,zone3 |
+-----------+-------------+-------------+--------------------+-------------------+
13 rows in set (0.001 sec)

obclient [oceanbase]>

5 清理回收站

OB 的回收站启用后，如果没有配置自动清理的话，里面的会一直保存。 建议在启用回收站配置自动清理。

http://www.cndba.cn/dave/article/131404

5.1 手工清理

登录 OB：

  1. MySQL 租户的管理员用户为 root 用户，Oracle 租户的管理员用户为 SYS 用户。
  2. 如果需要清理租户回收站对象，则需要使用 sys 租户登录数据库。

查看当前回收站里的内容：

obclient [(none)]> SHOW RECYCLEBIN;
+-------------------------------------+-------------------+----------+----------------------------+
| OBJECT_NAME                         | ORIGINAL_NAME     | TYPE     | CREATETIME                 |
+-------------------------------------+-------------------+----------+----------------------------+
| RECYCLE_$_100017_1672050541224936   | oracle001         | TENANT   | 2023-01-16 11:01:40.258000 |
| __recycle_$_100017_1673426335319344 | __idx_500788_idx1 | INDEX    | 2023-01-11 16:38:55.318878 |
| __recycle_$_100017_1673426335331800 | t1                | TABLE    | 2023-01-11 16:38:55.331481 |
| __recycle_$_100017_1673854707660504 | infotest          | DATABASE | 2023-01-16 15:38:27.660436 |
+-------------------------------------+-------------------+----------+----------------------------+
4 rows in set

彻底删除 租户：仅 sys 租户支持清理租户回收站对象。

obclient [(none)]> PURGE TENANT oracle001;
obclient [(none)]> PURGE TENANT RECYCLE_$_100017_1672050541224936;

彻底删除 数据库：仅 sys 租户和 MySQL 用户租户支持清理回收站中的数据库对象。

obclient [(none)]> PURGE DATABASE __recycle_$_100017_1673854707660504;

注意：这里不支持使用原始名称。

彻底删除 表：

obclient [(none)]> PURGE TABLE __recycle_$_100017_1673426335331800;
obclient [(none)]> PURGE TABLE t1;

彻底删除 索引：http://www.cndba.cn/dave/article/131404

obclient [(none)]> PURGE INDEX __recycle_$_100017_1673426335319344;

注意：这里不支持使用原始名称。

将所有对象从回收站中彻底清除

obclient [(none)]> PURGE RECYCLEBIN;

5.2 自动清理

OceanBase 数据库当前支持通过集群级配置项 recyclebin_object_expire_time 自动清理收站中过期的 Schema 对象，其默认值为 0s。其中：

  1. 值为 0s 时，表示关闭自动 Purge 回收站功能。
  2. 值为非 0s 时，表示 Purge 一段时间前进入回收站的对象。

因为该参数是集群级的，所以需要连接 SYS 租户进行配置。

该参数默认为 0，表示没有开启自动清理。http://www.cndba.cn/dave/article/131404

[dave@www.cndba.cn ~]$obclient -h192.168.1.21 -P2881 -uroot -p'xxxxx' -Doceanbase -A
Welcome to the OceanBase.  Commands end with ; or /g.
Your OceanBase connection id is 3221679644
Server version: OceanBase_CE 4.1.0.0 (r101010022023051821-f7379b26f8cd11f026e06846043550f9e0d42ead) (Built May 18 2023 21:14:14)

Copyright (c) 2000, 2018, OceanBase and/or its affiliates. All rights reserved.

Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.

obclient [oceanbase]>

obclient [oceanbase]> show parameters like '%recyclebin_object%'/G
*************************** 1. row ***************************
      zone: zone3
  svr_type: observer
    svr_ip: 192.168.1.23
  svr_port: 2882
      name: recyclebin_object_expire_time
 data_type: NULL
     value: 0s
      info: recyclebin object expire time, default 0 that means auto purge recyclebin off. Range: [0s, +∞)
   section: ROOT_SERVICE
     scope: CLUSTER
    source: DEFAULT
edit_level: DYNAMIC_EFFECTIVE

打开自动 Purge 回收站功能，并回收 7 天前进入回收站的 Schema 对象：

obclient [oceanbase]> ALTER SYSTEM SET recyclebin_object_expire_time = "7d";
Query OK, 0 rows affected (0.041 sec)

obclient [oceanbase]> show parameters like '%recyclebin_object%'/G
*************************** 1. row ***************************
      zone: zone2
  svr_type: observer
    svr_ip: 192.168.1.22
  svr_port: 2882
      name: recyclebin_object_expire_time
 data_type: NULL
     value: 7d
      info: recyclebin object expire time, default 0 that means auto purge recyclebin off. Range: [0s, +∞)
   section: ROOT_SERVICE
     scope: CLUSTER
    source: DEFAULT
edit_level: DYNAMIC_EFFECTIVE

关闭自动 Purge 回收站功能：

obclient [oceanbase]> ALTER SYSTEM SET recyclebin_object_expire_time = "0s";
Query OK, 0 rows affected (0.035 sec)

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dave

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人的一生应该是这样度过的：当他回首往事的时候，他不会因为虚度年华而悔恨，也不会因为碌碌无为而羞耻；这样，在临死的时候，他就能够说：“我的整个生命和全部精力，都已经献给世界上最壮丽的事业....."

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