Create and use a zero load node-DataWorks(DataWorks)-阿里云帮助中心

A zero load node is a control node that supports only dry-run scheduling and does not generate data. The scheduling system does not run the zero load node but directly returns a success response when the scheduling time of the zero load node arrives. This way, the zero load node does not occupy resources, and the descendant nodes of the zero load node can be run as expected. In most cases, a zero load node serves as the start node of a workflow or the output node of multiple branch nodes. This topic describes the use scenarios of a zero load node and how to create and use a zero load node.

Scenarios

Use a zero-load node in the following scenarios:

Manage workflows in scenarios in which dependencies between nodes are complex

If you manage multiple workflows, use a zero-load node as the orchestration start node for each.
Schedule nodes that have no lineage relationship

For a workflow with multiple, independent input branches, you can use a zero-load node as their common parent node. You can then set the workspace root node as the parent node of the zero-load node. This setup allows the workspace root to trigger the zero-load node, which in turn triggers the downstream business nodes. You can also use this method to set a specific schedule for the zero-load node, which controls the earliest start time for all its downstream branches.

Note
When the workspace root node is set as a dependency, it does not appear on the workflow canvas. You can view it in Operation Center after task deployment. For more information, see Basic O&M for scheduled tasks.

For example: oss_data_sync_dqc and rds_data_sync_dqc nodes have no lineage, so you cannot configure scheduling dependencies between them based on lineage. In this case, you can use a zero-load node (for example, workshop_start_dqc) as an orchestration start node to schedule these independent downstream branches. The branches run as soon as their respective conditions are met.

Note
When you use offline synchronization to import data from other sources into DataWorks, the destination tables lack an upstream lineage within DataWorks.
Configure scheduling dependencies for branch nodes in a workflow on nodes in another workflow

To make a workflow dependent on multiple branches in another, use a zero-load node to aggregate the outputs from those branches. Then, manually set this aggregation node's output as an input for the orchestration start node of the downstream workflow. For more information, see Configure a cross-workflow scheduling dependency.

Note
If a workflow has multiple output branches, you can create a new zero-load node (for example, a workflow_end node) that depends on all of them. When this final zero-load node runs successfully, it indicates that the entire workflow has completed.

Create and use a zero load node

Go to the DataStudio page.

Log on to the DataWorks console. In the top navigation bar, select the desired region. In the left-side navigation pane, choose Data Development and O&M > Data Development. On the page that appears, select the desired workspace from the drop-down list and click Go to Data Development.
Create a workflow.

If you already have a workflow, skip this step.
1. Hover over the icon and select Create Workflow.
2. In the Create Workflow dialog box, enter a Workflow Name.
3. Click Create.
Create a zero load node.
1. Hover over the icon and select Create Node > General > Zero-Load Node.
  
  Alternatively, find the target workflow, right-click it, and select Create Node > General > Zero-Load Node.
2. In the Create Node dialog box, enter a Name and select a Node Type and Path.
  
  Note
  The node name can contain only uppercase and lowercase letters, Chinese characters, digits, underscores (_), and periods (.). The name cannot exceed 128 characters.
3. Click OK to open the configuration tab for the zero-load node.
Configure scheduling properties for the zero load node.
To run the node periodically, click Scheduling Settings on the right of the node's configuration tab. Then, configure the scheduling properties for the task as needed:
- Configure the basic properties of the task. For more information, see Configure basic properties.
- Configure the scheduling period, rerun policy, and dependencies. For more information, see Configure time properties and Configure same-cycle scheduling dependencies.
  
  Note
  You must set the Rerun attribute and Parent Nodes properties before you can commit the node.
- Configure resource properties. For more information, see Configure resource properties.
Commit and deploy the task.
1. In the toolbar, click the icon to save the node.
2. In the toolbar, click the icon to commit the task.
3. In the Commit Node dialog box, enter a Change Description.
4. Click OK.
If your workspace is in standard mode, you must deploy the task to the production environment after committing it. To do so, click Deploy on the left side of the top navigation bar. For more information, see Deploy tasks.
View the scheduled task.
1. In the upper-right corner of the editor page, click Operation Center to go to the Operation Center for the production environment.
2. View the running scheduled tasks. For more information, see Manage auto-triggered tasks.
To view more details about scheduled tasks, you can click Operation Center in the top navigation bar. For more information, see Operation Center overview.