Enable the arbitration service for a tenant

You can enable the arbitration service for a tenant when you create the tenant. For more information, see Create a tenant. You can also enable the arbitration service for a tenant after the tenant is created. This topic describes how to enable the arbitration service for an existing tenant.

Prerequisites

• The arbitration service has been deployed in the cluster where the tenant resides. For more information about how to deploy the arbitration service, see Deploy an OceanBase cluster with two replicas and the arbitration service.

• The target tenant has two or four full-featured replicas.

  Note

  If you want to enable the arbitration service for a tenant, the number of full-featured replicas in the locality of the tenant must meet the specified requirement. The number of read-only replicas in the locality of the tenant is not limited. For example, if the locality of a tenant is F@z1,F@z2 or F@z1,F@z2,R@z3, you can enable the arbitration service for the tenant.

Procedure

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

   Note that you must specify the corresponding parameters in the following sample code based on your actual database configurations.

   obclient -h10.xx.xx.xx -P2883 -uroot@sys#obdemo -p***** -A
   

   For more information about how to connect to a database, see Overview (MySQL mode) or Overview (Oracle mode).

2. Execute the following statement to query the connection status of all nodes in the cluster.

   SELECT * FROM oceanbase.GV$OB_ARBITRATION_SERVICE_STATUS;
   

   The query result is as follows:

   +----------------+----------+-----------------------------+----------+
   | SVR_IP         | SVR_PORT | ARBITRATION_SERVICE_ADDRESS | STATUS   |
   +----------------+----------+-----------------------------+----------+
   | xx.xx.xx.197   |     2882 | xx.xx.xx.192:2882           | ACTIVE   |
   | xx.xx.xx.194   |     2882 | xx.xx.xx.192:2882           | ACTIVE   |
   +----------------+----------+-----------------------------+----------+
   2 rows in set
   

   The connection status between a node and the arbitration service is indicated by the value of the STATUS field in the query result.

   • ACTIVE: The arbitration service can communicate with the node. You can enable the arbitration service for the tenant only when the arbitration service can communicate with all nodes.
   • INACTIVE: The arbitration service cannot communicate with the node. In this case, you cannot enable the arbitration service for the tenant. Check the network communication between the node and the arbitration service.

3. Query the status of the arbitration service for the tenant.

   SELECT * FROM oceanbase.DBA_OB_TENANTS WHERE tenant_name = 'oracle001'\G
   

   The query result is as follows:

   *************************** 1. row ***************************
                    TENANT_ID: 1004
                  TENANT_NAME: oracle001
                  TENANT_TYPE: USER
                  CREATE_TIME: 2023-06-26 19:40:21.457857
                  MODIFY_TIME: 2023-06-27 13:51:47.053502
                 PRIMARY_ZONE: zone1;zone2
                     LOCALITY: FULL{1}@zone1, FULL{1}@zone2
            PREVIOUS_LOCALITY: NULL
           COMPATIBILITY_MODE: ORACLE
                       STATUS: NORMAL
                IN_RECYCLEBIN: NO
                       LOCKED: NO
                  TENANT_ROLE: PRIMARY
            SWITCHOVER_STATUS: NORMAL
             SWITCHOVER_EPOCH: 0
                     SYNC_SCN: 1687845116605766616
               REPLAYABLE_SCN: 1687845116605766616
                 READABLE_SCN: 1687845116605766616
           RECOVERY_UNTIL_SCN: 4611686018427387903
                     LOG_MODE: NOARCHIVELOG
   ARBITRATION_SERVICE_STATUS: DISABLED
                     UNIT_NUM = 1,
                   COMPATIBLE: 4.2.0.0
   1 row in set
   

   The arbitration service status of the tenant can be:

   • ENABLED: The arbitration service is enabled for the tenant.

   • DISABLED: The arbitration service is disabled for the tenant.

   • ENABLING: The arbitration service is being enabled for the tenant.

   • DISABLING: The arbitration service is being disabled for the tenant.

   The preceding query result shows that the value of the ARBITRATION_SERVICE_STATUS field is DISABLED, which indicates that the arbitration service is disabled for the tenant.

   For more information about the DBA_OB_TENANTS view, see DBA_OB_TENANTS.

4. Execute the following statement to enable the arbitration service for the tenant:

   ALTER TENANT tenant_name [SET] ENABLE_ARBITRATION_SERVICE = true;
   

   The tenant_name field specifies the name of the tenant for which you want to enable the arbitration service. The SET keyword is optional.

   The following sample statement enables the arbitration service for a tenant named oracle001:

   ALTER TENANT oracle001 ENABLE_ARBITRATION_SERVICE = true;
   

5. Query the DBA_OB_TENANTS view to check whether the arbitration service is enabled for the tenant.

   SELECT * FROM oceanbase.DBA_OB_TENANTS WHERE tenant_name = 'oracle001'\G
   

   The query result is as follows:

   *************************** 1. row ***************************
                    TENANT_ID: 1004
                  TENANT_NAME: oracle001
                  TENANT_TYPE: USER
                  CREATE_TIME: 2023-06-26 19:40:21.457857
                  MODIFY_TIME: 2023-06-27 13:54:29.486203
                 PRIMARY_ZONE: zone1;zone2
                     LOCALITY: FULL{1}@zone1, FULL{1}@zone2
            PREVIOUS_LOCALITY: NULL
           COMPATIBILITY_MODE: ORACLE
                       STATUS: NORMAL
                IN_RECYCLEBIN: NO
                       LOCKED: NO
                  TENANT_ROLE: PRIMARY
            SWITCHOVER_STATUS: NORMAL
             SWITCHOVER_EPOCH: 0
                     SYNC_SCN: 1687845307275557916
               REPLAYABLE_SCN: 1687845307275557916
                 READABLE_SCN: 1687845307131393135
           RECOVERY_UNTIL_SCN: 4611686018427387903
                     LOG_MODE: NOARCHIVELOG
   ARBITRATION_SERVICE_STATUS: ENABLED
                     UNIT_NUM = 1,
                   COMPATIBLE: 4.2.0.0
   1 row in set
   

   In the query result, the value of the ARBITRATION_SERVICE_STATUS field is ENABLED, which indicates that the arbitration service is enabled for the tenant.

6. After you enable the arbitration service, some log streams of the tenant may still have no arbitration members. These log streams cannot be downgraded or upgraded. Check whether all log streams have arbitration members.

   After you enable the arbitration service, the existing log streams of the tenant can use the arbitration service, but the new log streams created after the arbitration service is enabled may lack arbitration members and cannot be upgraded or downgraded. This is because a log stream is created in non-strict mode and the arbitration member may not be created. You can execute the following statement to check whether all log streams of the tenant have arbitration members:

   Here is a sample statement:

   (SELECT distinct ls_id FROM GV$OB_LOG_STAT WHERE tenant_id = tenantid) EXCEPT
   (SELECT ls_id FROM GV$OB_LOG_STAT WHERE tenant_id = tenantid AND role = 'LEADER' AND arbitration_member = 'arb_server_ip:arb_server_port');
   

   The parameters are described as follows:

   • tenantid: the ID of the tenant for which the arbitration service is enabled.

   • arb_server_ip: the IP address of the server on which the arbitration service is deployed.

   • arb_server_port: the remote procedure call (RPC) port for the arbitration service. By default, Port 2882 is used.

   Here is an example:

   (SELECT distinct ls_id FROM GV$OB_LOG_STAT WHERE tenant_id = 1004) EXCEPT
   (SELECT ls_id FROM GV$OB_LOG_STAT where tenant_id = 1004 and role = 'LEADER' and arbitration_member = '100.xx.xx.xx:2882');
   

   If the query result is empty, all log streams have arbitration members, and the arbitration service is available. Otherwise, RootService will add arbitration members to log streams that lack arbitration members in the background. You can check whether an arbitration member addition task is running by querying the CDB_OB_LS_ARB_REPLICA_TASKS view.

   After the task is completed, you can query the CDB_OB_LS_ARB_REPLICA_TASK_HISTORY view to confirm the task execution result. If the task succeeded, arbitration members are added to log streams, and the arbitration service is available. If the task failed, contact OceanBase Technical Support for assistance.

   For more information about columns in the GV$OB_LOG_STAT view, see GV$OB_LOG_STAT.

References

For more information about the arbitration service, see the following topics:

• Deploy an OceanBase cluster with two replicas and the arbitration service

• Disable the arbitration service for a tenant

• Modify the log stream downgrade control time

• Replace the arbitration service for a cluster

• Remove the arbitration service for a cluster