MODIFY PAXOS_REPLICA_NUM

Purpose

You can use this statement to modify the paxos_replica_num parameter for a log stream, which defines the number of Paxos members for electing the leader for the log stream.

Limitations and considerations

• This statement modifies the paxos_replica_num parameter for a single log stream at a time.

• One log stream of a tenant supports only one replica task at a time, such as a task to add replicas, remove replicas, convert the type of a replica, modify paxos_replica_num, or migrate replicas.

  Note

  You can query ongoing replica tasks from the CDB_OB_LS_REPLICA_TASKS view in the `sys` tenant or from the DBA_OB_LS_REPLICA_TASKS view in a user tenant.

Required privileges

To execute this statement, you must have the ALTER SYSTEM privilege. For more information about privileges in OceanBase Database, see Privilege types in MySQL mode and Privilege types in Oracle mode.

Syntax

ALTER SYSTEM MODIFY
    LS [=] ls_id
    PAXOS_REPLICA_NUM [=] paxos_replica_num
    [TENANT [=] 'tenant_name'];

Parameters

Examples

Execute the following statement in the sys tenant to change the value of the paxos_replica_num parameter to 2 for the log stream with the ID of 1002 in the mysql001 tenant.

ALTER SYSTEM MODIFY
    LS = 1002
    PAXOS_REPLICA_NUM = 2
    TENANT = 'mysql001';

For more information about how to modify the paxos_replica_num parameter for a log stream, see Modify the number of Paxos replicas of a log stream.

References

• For information about how to add a replica, see ADD REPLICA.
• For information about how to drop a replica, see REMOVE REPLICA.
• For information about how to modify the type of a replica, see MODIFY REPLICA.
• For information about how to migrate a replica, see MIGRATE REPLICA.
• For information about how to cancel a replica task, see CANCEL REPLICA TASK.