Note
For V4.4.2, this parameter is available starting from V4.4.2 BP2.
Overview
The enable_standby_semi_sync parameter specifies whether to enable semi-synchronous replication for the standby database (standby tenant).
Privilege requirements
Query parameters
Both the
systenant and all user tenants can query this parameter using theSHOW PARAMETERSstatement or theGV$OB_PARAMETERSview.Modify parameters
Both the
systenant and user tenants can modify this parameter.
Attributes
Attribute |
Description |
|---|---|
| Parameter type | Bool |
| Default Value | False |
| Value range |
|
| Modifiable | Yes, you can use theALTER SYSTEM SETStatement modification. |
| Whether to restart the OBServer node for the change to take effect | No, the setting takes effect immediately. |
Usage instructions
You can modify the value of this parameter only when the standby database is in the
MAXIMUM PERFORMANCEprotection mode.We recommend that you perform this operation during off-peak hours and wait for about 10 seconds before restoring normal traffic.
In other protection modes (except
MAXIMUM PERFORMANCE), if you want the standby database to enter semi-synchronous mode, you can first set the value of this parameterenable_standby_semi_synctoTruewhen the standby database is inMAXIMUM PERFORMANCEmode, and then switch it toMAXIMUM AVAILABILITYorMAXIMUM PROTECTIONmode. After the switch is successful, this parameter will become read-only.
Configuration example
Enable the semi-synchronous replication mode for the standby database.
obclient> ALTER SYSTEM SET enable_standby_semi_sync = True;