Note
- For V4.3.x, this parameter is available starting with V4.3.5.
- For V4.2.x, this parameter is available starting with V4.2.5.
Description
replica_parallel_migration_mode specifies the mode of the log stream replica parallel migration feature.
Privilege requirements
Query the parameter
The
systenant and all user tenants can use theSHOW PARAMETERSstatement or theGV$OB_PARAMETERSview to query this parameter.Modify the parameter
The
systenant and user tenants can modify this parameter.
Attributes
| Attribute | Description |
|---|---|
| Type | String |
| Default value | auto |
| Value range |
|
| Modifiable | Yes. You can use the ALTER SYSTEM SET statement to modify the parameter. |
| Effective upon OBServer node restart | No. The setting takes effect immediately. |
Considerations
When you set this parameter, note the following:
In a physical standby database scenario, the primary and standby tenants have different requirements for the log stream replica parallel migration feature:
In a normal scenario, the primary tenant may not need to use the parallel migration feature. When multiple replicas are migrated in parallel, a large amount of data is copied, which may affect the I/O performance of the leader replica.
The standby tenant has a high demand for parallel migration. Parallel migration can reduce the probability of replica rebuilds on the standby tenant.
When you use the parallel migration feature, minimize the impact on the existing primary database (primary tenant). If you want to accelerate scaling in and out, you can enable the parallel migration feature.
In a physical standby database scenario, both the primary and standby tenants need to set this parameter.
Examples
Enable the parallel migration feature for the current user tenant.
obclient> ALTER SYSTEM SET replica_parallel_migration_mode = 'on';