Purpose
You can use this statement to remove a replica of a log stream.
Limitations and considerations
Make sure that the log stream still meets the majority principle after a replica is removed. Otherwise, the O&M command returns an error.
This statement removes only one replica at a time.
For the same log stream of a tenant, except for replica migration tasks that can be executed in parallel, other disaster recovery tasks (including adding replicas, deleting replicas, converting replica types, and modifying the quorum size of the log stream) can only be executed one at a time.
Note
You can query ongoing replica tasks from the
CDB_OB_LS_REPLICA_TASKSview in thesystenant or from theDBA_OB_LS_REPLICA_TASKSview 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 REMOVE REPLICA
LS [=] ls_id
SERVER [=] 'svr_ip:svr_port'
[PAXOS_REPLICA_NUM [=] paxos_replica_num]
[TENANT [=] 'tenant_name'];
Parameters
| Parameter | Description |
|---|---|
| ls_id | The ID of the log stream for which you want to remove a replica. |
| svr_ip:svr_port | The IP address and port number of the OBServer node where the replica to be removed resides, for example, xxx.xx.xxx.001:2882. |
| paxos_replica_num | Optional. The number of Paxos members for electing the leader for the log stream. If this parameter is not explicitly specified, the default value is used. A log stream supports a maximum of seven full-featured replicas.
NoticeThe value of the
|
| tenant_name | Optional. The name of the target tenant. If this parameter is not explicitly specified, the name of the current tenant is used.
Notice
|
Examples
Execute the following statement in the sys tenant to remove a replica of a log stream in the mysql001 tenant:
ALTER SYSTEM REMOVE REPLICA
LS = 1001
SERVER = 'xxx.xxx.xxx.001:2882'
PAXOS_REPLICA_NUM = 2
TENANT = 'mysql001';
For more information about how to remove a replica, see Remove replicas.
References
- For information about how to add a replica, see ADD 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 modify the
PAXOS_REPLICA_NUMparameter for a replica, see MODIFY PAXOS_REPLICA_NUM. - For information about how to cancel a replica task, see CANCEL REPLICA TASK.