Lock and unlock a tenant

OceanBase Database allows you to lock a tenant. New connections cannot be created on a locked tenant, but existing connections are not affected. This topic describes how to lock and unlock a tenant.

Background

You can execute the ALTER TENANT statement to lock or unlock a tenant for emergency responses to exceptions or for O&M changes.

• Emergency responses to exceptions: If a tenant is recovering from an exception, you can lock this tenant to prevent business traffic from affecting the recovery procedure with the consent of the customer. If you lock a tenant as an emergency action, you must kill the session after you lock the tenant.

• O&M changes: If a tenant must be removed, make sure that phased removal and data rollback are supported. In this case, you can lock the tenant to observe the impact on the business system.

Lock a tenant

1. Log on to the sys tenant of the cluster as the root user.

   obclient -h172.30.xx.xx -P2883 -uroot@sys#cluster -p**** -A
   

2. Execute the following statement to go to the database named oceanbase:

   obclient [(none)]> USE oceanbase;
   

3. Query the DBA_OB_TENANTS view for information about a tenant.

   To query the locking status of the mq_t1 tenant, execute the following statement:

   obclient [oceanbase]> SELECT TENANT_ID,TENANT_NAME,LOCKED FROM DBA_OB_TENANTS WHERE TENANT_NAME = 'mq_t1';
   +-----------+-------------+--------+
   | TENANT_ID | TENANT_NAME | LOCKED |
   +-----------+-------------+--------+
   |      1036 | mq_t1       | NO     |
   +-----------+-------------+--------+
   1 row in set
   

   For more information about the DBA_OB_TENANTS view, see oceanbase.DBA_OB_TENANTS.

4. Execute the ALTER TENANT statement to lock the tenant.

   To lock the mq_t1 tenant, execute the following statement.

   obclient [oceanbase]> ALTER TENANT mq_t1 LOCK;
   Query OK, 0 rows affected
   

   For more information about the ALTER TENANT statement, see ALTER TENANT.

5. Query the DBA_OB_TENANTS view to verify whether the tenant is successfully locked.

   obclient [oceanbase]> SELECT TENANT_ID,TENANT_NAME,LOCKED FROM DBA_OB_TENANTS WHERE TENANT_NAME = 'mq_t1';
   +-----------+-------------+--------+
   | TENANT_ID | TENANT_NAME | LOCKED |
   +-----------+-------------+--------+
   |      1036 | mq_t1       | YES    |
   +-----------+-------------+--------+
   1 row in set
   

Unlock a tenant

1. Log on to the sys tenant of the cluster as the root user.

   obclient -h172.30.xx.xx -P2883 -uroot@sys#cluster -p**** -A
   

2. Execute the following statement to go to the database named oceanbase:

   obclient [(none)]> USE oceanbase;
   

3. Query the DBA_OB_TENANTS view for information about a tenant.

   To query the locking status of the mq_t1 tenant, execute the following statement:

   obclient [oceanbase]> SELECT TENANT_ID,TENANT_NAME,LOCKED FROM DBA_OB_TENANTS WHERE TENANT_NAME = 'mq_t1';
   +-----------+-------------+--------+
   | TENANT_ID | TENANT_NAME | LOCKED |
   +-----------+-------------+--------+
   |      1036 | mq_t1       | YES    |
   +-----------+-------------+--------+
   1 row in set
   

   For more information about the DBA_OB_TENANTS view, see oceanbase.DBA_OB_TENANTS.

4. Execute the ALTER TENANT statement to unlock the tenant.

   To unlock the mq_t1 tenant, execute the following statement:

   obclient [oceanbase]> ALTER TENANT mq_t1 UNLOCK;
   Query OK, 0 rows affected
   

   For more information about the ALTER TENANT statement, see ALTER TENANT.

5. Query the DBA_OB_TENANTS view to verify whether the tenant is successfully locked.

   obclient [oceanbase]> SELECT TENANT_ID,TENANT_NAME,LOCKED FROM DBA_OB_TENANTS WHERE TENANT_NAME = 'mq_t1';
   +-----------+-------------+--------+
   | TENANT_ID | TENANT_NAME | LOCKED |
   +-----------+-------------+--------+
   |      1036 | mq_t1       | NO     |
   +-----------+-------------+--------+
   1 row in set