REMOVE REPLICA

Purpose

This statement is used to remove a replica from a log stream.

Limitations and considerations

• Ensure that the log stream can still form a majority after the replica is removed, otherwise an error will be returned when executing maintenance commands.

• This statement can only remove one replica at a time.

• For the same log stream of a tenant, except for replica migration tasks, only one disaster recovery task (including adding a replica, removing a replica, changing the replica type, and modifying the quorum size of the log stream) can be executed at a time.

  Note

  For the sys tenant, you can query the CDB_OB_LS_REPLICA_TASKS view to check whether a disaster recovery task is in progress. For a user tenant, you can query the DBA_OB_LS_REPLICA_TASKS view to check whether a disaster recovery task is in progress.

Privilege requirements

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

Syntax

ALTER SYSTEM REMOVE REPLICA
    LS [=] ls_id
    SERVER [=] 'svr_ip:svr_port'
    [PAXOS_REPLICA_NUM [=] paxos_replica_num]
    [TENANT [=] 'tenant_name'];

Parameters

Examples

Execute the following statement in the sys tenant to remove a replica from the log stream of the mysql001 tenant.

ALTER SYSTEM REMOVE REPLICA
    LS = 1001
    SERVER = 'xxx.xxx.xxx.001:2882'
    PAXOS_REPLICA_NUM = 2
    TENANT = 'mysql001';

For more examples of removing log stream replicas, see Reduce replicas.

References

• For information about manually adding a log stream replica, see ADD REPLICA.
• For information about changing the type of a log stream replica, see MODIFY REPLICA.
• For information about migrating a log stream replica, see MIGRATE REPLICA.
• For information about modifying the PAXOS_REPLICA_NUM of a log stream, see MODIFY PAXOS_REPLICA_NUM.
• For information about canceling a log stream replica task, see CANCEL REPLICA TASK.