1078919169 DWS Data Instance Connections Exceed the Threshold

Alarm Description

This alarm is generated when the number of client connections to a CN exceeds the threshold (specified by parameter max_connections*connection_alarm_rate) configured in the postgresql.conf file.

Alarm Attributes

Alarm ID	Alarm Category	Alarm Severity	Alarm Type	Service Type	Auto Cleared
1078919169	Tenant plane	Important	Service quality alarm	DWS instance	Yes

Alarm Parameters

The number of parameters varies according to alarms.

Type	Parameter	Description
Location Information	instance_id	ID of the instance for which the alarm is generated
	instance_name	Name of the instance that reports the alarm
	domain_name	Domain name for which the alarm is generated
	domain_id	Domain ID for which the alarm is generated
	datastore_type	Type of the data storage for which the alarm is generated
	instance_role	Role of the instance for which the alarm is generated
	component_instance_name	Name of the component instance that reports the alarm, for example, cn_5001.
Additional Information	CloudService	Name of the cloud service for which the alarm is generated
	resourceId	Resource ID for which the alarm is generated
	resourceIdName	Resource for which the alarm is generated
	domain_name	Domain name for which the alarm is generated
	domain_id	Domain ID for which the alarm is generated

Impact on the System

New clients cannot connect to a CN.

System Actions

None

Possible Causes

The number of clients connected to a CN exceeds the threshold (specified by parameter max_connections*connection_alarm_rate) configured in the postgresql.conf file.

Procedure

Log in to the DWS console.
On the Alarm page, view the alarms generated in the last seven days.
Choose Cluster > Cluster List and locate the cluster based on the cluster information in the alarm details.
Click the cluster name to go to the cluster details page. Choose Parameter Modifications, search for max_connections in the search box on the right of the parameter list, and change its value.
Determine whether to increase the value of max_connections for CNs and DNs based on the following rules. The default value is 800 for CNs and 5,000 for DNs.
- Increasing the value of max_connections for CNs will increase the number of concurrent queries connected to DNs. Therefore, you need to increase the values of max_connections and comm_max_stream for DNs.
- Increase the value of max_connections for CNs/DNs by twice. For clusters with a small value, you can increase it by four times.
- To avoid failures in the preparation step, the value of max_prepared_transactions should at least be equal to that of max_connections. This ensures that each session has a prepared transaction in waiting state.
Figure 1 Modifying parameters
Confirm the information and click Save.