Lock and unlock a tenant

OceanBase Database supports locking tenants. When a tenant is locked, new connections cannot be created on that tenant, but existing connections remain unchanged. This topic describes how to lock and unlock a tenant.

Background information

Tenants can be locked and unlocked using the ALTER TENANT statement. It is applicable in emergency handling scenarios and operational change scenarios.

• Emergency handling scenarios: If a tenant is experiencing issues and being recovered, you can lock the tenant to prevent business traffic from affecting the recovery process, with the consent of the customer. After locking the tenant, you must kill the corresponding sessions.

• Operational change scenarios: For example, if a tenant needs to be taken offline, the offline process must follow principles such as gray-scale release and rollback. Locking the tenant can be one of the steps to observe the impact on the business system.

Lock a tenant

1. Log in to the sys tenant of the cluster using the root user.

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

2. Access the database named oceanbase.

   USE oceanbase;
   

3. Query the tenant information through the DBA_OB_TENANTS view. For example, to query the locking status of the mq_t1 tenant:

   obclient [oceanbase]> SELECT TENANT_ID,TENANT_NAME,LOCKED FROM oceanbase.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 DBA_OB_TENANTS.

4. Execute the ALTER TENANT statement to lock the tenant. For example, to lock the mq_t1 tenant:

   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 check whether the tenant has been 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 in to the sys tenant of the cluster using the root user.

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

2. Access the database named oceanbase.

   obclient [(none)]> USE oceanbase;
   

3. Query the tenant information through the DBA_OB_TENANTS view. For example, to query the locking status of the mq_t1 tenant:

   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 DBA_OB_TENANTS.

4. Execute the ALTER TENANT statement to unlock the tenant. For example, to unlock the mq_t1 tenant:

   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 check whether the tenant has been successfully unlocked.

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