Note
For V4.2.0, this parameter is available starting with V4.2.0.
Description
archive_lag_target specifies the maximum allowed delay for log archiving of a tenant.
Privilege requirements
Query the parameter
You can use the
SHOW PARAMETERSstatement or query theGV$OB_PARAMETERSview to query the value of this parameter. Thesystenant and all user tenants have the privilege.Modify the parameter
The
systenant and user tenants have the privilege.
Attributes
| Attribute | Description |
|---|---|
| Type | Time |
| Default value | 120s |
| Value range | [0ms, 7200s] |
| 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
In a physical standby database scenario based on log archiving, you can adjust the value of the
archive_lag_targetparameter of the primary tenant to half of the delay requirement of the standby tenant. After the adjustment, all standby tenants under the primary tenant will be affected.In other scenarios, such as a physical standby database scenario based on network, we recommend that you adjust the value of the
archive_lag_targetparameter of the primary tenant based on the write pressure of the tenant and the requirement for the timeliness of archiving. Under the premise of meeting the timeliness requirement, we recommend that you ensure that a log file of at least 64 MB is generated within the period specified by thearchive_lag_targetparameter for a single log stream.Note
Log files and archive files are in the same format. A log file can be fully uploaded to generate a Normal archive file.
Examples
Set the maximum allowed delay for log archiving of a tenant to 120s.
obclient> ALTER SYSTEM SET archive_lag_target ='120s';