View locality

This topic describes how to query for the types and distribution of replicas for tenants from the oceanbase.DBA_OB_TENANTS view.

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

Procedure

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

   obclient -h172.30.xxx.xxx -P2883 -uroot@sys#obdemo -pxxxx -A
   

2. Access the database named oceanbase.

   obclient>use oceanbase;
   

3. Query for the types and distribution of replicas for tenants from the oceanbase.DBA_OB_TENANTS view.

   obclient> SELECT TENANT_ID,TENANT_NAME,TENANT_TYPE,PRIMARY_ZONE,LOCALITY FROM oceanbase.DBA_OB_TENANTS;
   +-----------+-------------+-------------+----------------------------------------+------------------------------------------------------------------+
   | TENANT_ID | TENANT_NAME | TENANT_TYPE | PRIMARY_ZONE                           | LOCALITY                                                         |
   +-----------+-------------+-------------+----------------------------------------+------------------------------------------------------------------+
   |         1 | sys         | SYS         | sa128_obv4_2;sa128_obv4_1,sa128_obv4_3 | FULL{1}@sa128_obv4_1, FULL{1}@sa128_obv4_2, FULL{1}@sa128_obv4_3 |
   |      1001 | META$1002   | META        | sa128_obv4_2;sa128_obv4_1,sa128_obv4_3 | FULL{1}@sa128_obv4_1, FULL{1}@sa128_obv4_2, FULL{1}@sa128_obv4_3 |
   |      1002 | midas0_3790 | USER        | sa128_obv4_2;sa128_obv4_1,sa128_obv4_3 | FULL{1}@sa128_obv4_1, FULL{1}@sa128_obv4_2, FULL{1}@sa128_obv4_3 |
   |      1003 | META$1004   | META        | sa128_obv4_1,sa128_obv4_2              | FULL{1}@sa128_obv4_1, FULL{1}@sa128_obv4_2                       |
   |      1004 | mq_t1       | USER        | sa128_obv4_1,sa128_obv4_2              | FULL{1}@sa128_obv4_1, FULL{1}@sa128_obv4_2                       |
   +-----------+-------------+-------------+----------------------------------------+------------------------------------------------------------------+
   5 rows in set
   

   Note

   The locality in the preceding example is FULL{1}@sa128_obv4_1, FULL{1}@sa128_obv4_2. In practice, the majority principle must be met after you add zones.

The LOCALITY column in the DBA_OB_TENANTS table indicates the types and distribution of replicas for tenants. It describes the types of replicas for tenants and the distribution of replicas across zones in the cluster.

For example, LOCALITY = 'FULL{1}@sa128_obv4_1, FULL{1}@sa128_obv4_2' for the mq_t1 tenant indicates that the tenant has one full-featured replica in both sa128_obv4_1 and sa128_obv4_2.

References

• Locality

• Modify locality

• Add replicas