Note
This parameter is available starting with V4.2.0.
Description
archive_lag_target specifies the maximum delay allowed for log archiving.
Privilege requirements
Query the parameter
The
systenant and all user tenants can query this parameter by using theSHOW PARAMETERSstatement or theGV$OB_PARAMETERSview.Modify the parameter
The
systenant and user tenants can modify this parameter.
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
For a physical standby database based on log archiving, you can set the
archive_lag_targetparameter to half of the maximum delay allowed for the standby tenant.For other scenarios, such as a physical standby database based on network, we recommend that you set the
archive_lag_targetparameter based on the write pressure of the tenant and the required archiving timeliness. If the timeliness requirement is met, ensure that a log file of at least 64 MB is generated within the cycle specified by thearchive_lag_targetparameter.Note
Log files and archive files are in the same format. A log file can be uploaded as a Normal archive file.
Examples
Set the maximum delay allowed for log archiving to 120s.
obclient> ALTER SYSTEM SET archive_lag_target ='120s';