This topic describes the definition of an isolated node, the reasons why an isolated node is generated, and the solutions to an isolated node.
Definition
An isolated node is a node that does not have an ancestor node. When you right-click an isolated node and select Show Ancestor Nodes on the Cycle Task or Cycle Instance page, no ancestor node appears. An isolated node cannot be automatically scheduled. If multiple nodes depend on an isolated node, your business may be severely affected. An alert notification is automatically sent if an isolated node is identified. We recommend that you handle the alert at the earliest opportunity. For information about the alerting mechanism for an isolated node, see the Monitoring and alerting section in this topic.
In DataWorks, except for the root node in a workspace, each auto triggered node that you created must have ancestor nodes. If you do not configure ancestor nodes for an auto triggered node, the auto triggered node cannot be scheduled as expected.
Causes and solutions
Cause | Description | Solution |
An auto triggered node and its ancestor node have different instance generation modes. | An auto triggered node is newly created with the Instance Generation Mode parameter set to Immediately After Deployment. This node depends on only another newly created node whose Instance Generation Mode parameter is set to Next Day. In this case, the current auto triggered node becomes an isolated node because no instances are generated for the ancestor node on the current day. | Modify the Instance Generation Mode parameter for the ancestor node and deploy the ancestor node again. For more information, see Scenario 3: Configure different instance generation modes for an auto triggered node and its ancestor node. |
The ancestor node of an auto triggered node is out of the specified validity period for scheduling. | In DataWorks, no instances are generated for nodes that are out of the specified validity period for scheduling. If an auto triggered node depends on only one node, and the ancestor node is out of the specified validity period for scheduling, the auto triggered node becomes an isolated node. | Modify the Validity Period parameter in the Schedule section of the Properties tab on the configuration tab of the ancestor node. For more information, see Validity period. |
The output of the ancestor node of an auto triggered node is changed. | An auto triggered node depends on only one node. If the business of the ancestor node changes, the output of the ancestor node is changed accordingly. As a result, dependencies between the auto triggered node and its ancestor node become invalid, and the auto triggered node becomes an isolated node. | Reconfigure dependencies for the auto triggered node. For more information, see Impacts of removing or changing the output of a node. |
Cross-workspace dependencies are configured for an auto triggered node, but Periodic scheduling is not turned on for the workspace in which the ancestor node of the auto triggered node resides. | If an auto triggered node depends only on one node, the auto triggered node and its ancestor node reside in different workspaces, and Periodic scheduling is not turned on for the workspace in which the ancestor node resides, the auto triggered node becomes an isolated node. | Contact the owner of the workspace to turn on Periodic scheduling or remove the cross-workspace dependencies. For information about how to turn on Periodic scheduling for a workspace, see Configure scheduling settings. |
The scheduling time of an intermediate task is not within the specified time period for data backfilling. | If the scheduling time of an intermediate task for which upstream and downstream scheduling dependencies are configured does not fall within the time period for data backfilling, a descendant node of the node that runs the intermediate task may become an isolated node. Sample scenarios:
Data that is within the time period from | Backfill data for the intermediate task within the same specified time period. For more information, see Backfill data for an auto triggered node and view data backfill instances generated for the node. In this example, you must backfill data for Task B within the time period from |
Monitoring and alerting
DataWorks generates auto triggered node instances for auto triggered nodes every night. The auto triggered node instances are scheduled to run on the next day. DataWorks provides built-in alert rules to monitor and scan auto triggered nodes on a regular basis. This ensures that auto triggered nodes can be run as scheduled and instances can be generated for auto triggered nodes. If an exception occurs, an alert is triggered. An alert notification is automatically sent if an isolated node is identified. We recommend that you handle the alert at the earliest opportunity.
DataWorks scans auto triggered nodes at 09:00, 12:00, and 16:00 every day. If an exception occurs, DataWorks sends an alert notification. However, if an exception occurs within 10 minutes before a scan starts, the exception is out of the scanning scope of the current scan and can be detected until the next scan.
Alert rules for isolated nodes are built-in rules provided by DataWorks. After an alert rule is triggered, an alert notification is sent to the node owner by text message or email. You can change the alert contact on the Rule Management page. For more information, see Create a custom alert rule.
View isolated nodes
In Operation Center, you can go to the Focus on section of the Workbench Overview tab on the Overview page to view the number and details of isolated nodes.