Start a service

You can execute the START SERVICE statement to start an existing service.

Limitations

You cannot execute the START SERVICE statement in a session created based on a service name.

Prerequisites

• You have the ALTER SYSTEM privilege.

• The units for the tenant do not contain temporarily offline OBServer nodes. Otherwise, the temporarily offline OBServer nodes cannot provide the service specified by the service name after you execute the START SERVICE statement. Therefore, we recommend that you wait until the temporarily offline OBServer nodes are recovered or permanently offline before you execute the START SERVICE statement.

  For more information about how to query temporarily offline OBServer nodes in the units for a tenant, see Prerequisites in Create a service.

Procedure

1. Log in to a user tenant or the sys tenant of the cluster as the tenant administrator.

   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
   

2. Check whether the service to be started is in the STARTED state.

   For more information, see Query the service status.

   If the service is not in the STARTED state, verify that the SWITCHOVER_STATUS value of the tenant is NORMAL, which indicates that the tenant is not in an intermediate state during primary/standby switchover. You can query the SWITCHOVER_STATUS value of a tenant in either of the following ways:

   • Query the SWITCHOVER_STATUS value of a specified tenant in the sys tenant.

   obclient [oceanbase]> SELECT TENANT_ID, TENANT_NAME, SWITCHOVER_STATUS FROM oceanbase.DBA_OB_TENANTS WHERE TENANT_NAME = mysql_tenant;
   

   • Query the SWITCHOVER_STATUS value of a user tenant in the current tenant.

     MySQL mode

     Oracle mode

     The query statement in MySQL mode is as follows:

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

     The query statement in Oracle mode is as follows:

     obclient [SYS]> SELECT TENANT_ID, TENANT_NAME, SWITCHOVER_STATUS FROM SYS.DBA_OB_TENANTS;
     

3. Start the service.

   Here is an example:

   ALTER SYSTEM START SERVICE service_name [TENANT [=] tenant_name];
   

   The parameters are described as follows:

   • service_name: the name of the service to be started.
   • TENANT [=] tenant_name: the name of the tenant for which you want to start the service. This parameter is valid only in the sys tenant.

   Here are some examples:

   • Start a service named s_hz for a tenant named mysql_tenant in the sys tenant.

     obclient [oceanbase]> ALTER SYSTEM START SERVICE s_hz TENANT = mysql_tenant;
     

   • Start a service named s_hz in a user tenant.

     obclient > ALTER SYSTEM START SERVICE s_hz;
     

   If Query OK is returned, you can connect to all OBServer nodes except the permanently offline ones in the units for the tenant by specifying the service name. If OB_SERVICE_NOT_FULLY_STARTED is returned, you can connect to only some of OBServer nodes except the permanently offline ones in the units for the tenant by specifying the service name. You can query the connectable OBServer nodes from the CDB_OB_TENANT_EVENT_HISTORY view in the sys tenant or the DBA_OB_TENANT_EVENT_HISTORY (MySQL mode) or DBA_OB_TENANT_EVENT_HISTORY (Oracle mode) view in a user tenant.

References

• Query the service status
• Stop a service
• Delete a service