DataWorks provides DRDS nodes that you can use to develop and periodically schedule DRDS tasks and integrate DRDS tasks with other types of tasks. This topic describes how to use a DRDS node to develop tasks.
Background information
PolarDB for Xscale (PolarDB-X), formerly called DRDS, is a distributed database service. It allows you to perform a scale-out operation to upgrade a relational database to a distributed system that supports storage and access of large amounts of data. PolarDB-X maintains the original features of relational databases, such as MySQL. For more information, see Overview.
Prerequisites
A workflow is created.
Development operations in different types of compute engines are performed based on workflows in DataStudio. Therefore, before you create a node, you must create a workflow. For more information, see Create a workflow.
A DRDS data source is added.
You must add your PolarDB-X database to DataWorks as a DRDS data source before you can use the data source to access data in the database. For information about how to add a data source, see Add and manage data sources. For information about how to use a DRDS data source in DataWorks, see DRDS (PolarDB-X 1.0) data source.
NoteYou can create DRDS nodes based on only DRDS data sources that are added to DataWorks in Java Database Connectivity (JDBC) connection string mode.
A network connection is established between your data source and a resource group.
You must make sure that the desired data source is connected to the resource group that you want to use. For more information about how to configure network connectivity, see Establish a network connection between a resource group and a data source.
(Required if you use a RAM user to develop tasks) The RAM user is added to the DataWorks workspace as a member and is assigned the Development or Workspace Administrator role. The Workspace Administrator role has more permissions than necessary. Exercise caution when you assign the Workspace Administrator role. For more information about how to add a member and assign roles to the member, see Add workspace members and assign roles to them.
Step 1: Create a DRDS node
Go to the DataStudio page.
Log on to the DataWorks console. In the left-side navigation pane, choose . On the page that appears, select the desired workspace from the drop-down list and click Go to DataStudio.
On the DataStudio page, find the desired workflow, right-click the workflow name, and then choose .
In the Create Node dialog box, configure the Name parameter and click Confirm. Then, you can use the created node to develop and configure tasks.
Step 2: Develop a DRDS task
(Optional) Select a DRDS data source
If multiple DRDS data sources are added to your workspace, you must select one from the Select Data Source drop-down list in the upper part of the configuration tab of the node based on your business requirements. If only one DRDS data source is added to your workspace, the DRDS data source is used to develop tasks.
You can create DRDS nodes based on only DRDS data sources that are added to DataWorks in Java Database Connectivity (JDBC) connection string mode.
Develop SQL code: Simple example
In the code editor on the configuration tab of the DRDS node, write task code. Sample code:
SELECT * FROM usertablename;Develop SQL code: Use scheduling parameters
DataWorks provides scheduling parameters whose values are dynamically replaced in the code of a task based on the configurations of the scheduling parameters in periodic scheduling scenarios. You can define variables in the task code in the ${Variable} format and assign values to the variables in the Scheduling Parameter section of the Properties tab. For information about the supported formats of scheduling parameters and how to configure scheduling parameters, see Supported formats of scheduling parameters and Configure and use scheduling parameters.
Sample code:
SELECT '${var}'; -- You can assign a specific scheduling parameter to the var variable.
Step 3: Configure task scheduling properties
If you want the system to periodically run a task on the node, you can click Properties in the right-side navigation pane on the configuration tab of the node to configure task scheduling properties based on your business requirements. For more information, see Overview.
You must configure the Rerun and Parent Nodes parameters on the Properties tab before you commit the task.
Step 4: Debug task code
You can perform the following operations to check whether the task is configured as expected based on your business requirements:
Optional. Select a resource group and assign custom parameters to variables.
Click the
icon in the top toolbar of the configuration tab of the node. In the Parameters dialog box, select a resource group for scheduling that you want to use to debug and run task code. If you use scheduling parameters in your task code, assign the scheduling parameters to variables as values in the task code for debugging. For more information about the value assignment logic of scheduling parameters, see Debugging procedure.
Save and execute SQL statements.
In the top toolbar, click the
icon to save SQL statements. Then, click the 
icon to execute the SQL statements. Optional. Perform smoke testing.
You can perform smoke testing on the task in the development environment to check whether the task is run as expected when you commit the task or after you commit the task. For more information, see Perform smoke testing.
Step 5: Commit and deploy the task
After a task on a node is configured, you must commit and deploy the task. After you commit and deploy the task, the system runs the task on a regular basis based on scheduling configurations.
Click the
icon in the top toolbar to save the task. Click the
icon in the top toolbar to commit the task. In the Submit dialog box, configure the Change description parameter. Then, determine whether to review task code after you commit the task based on your business requirements.
NoteYou must configure the Rerun and Parent Nodes parameters on the Properties tab before you commit the task.
You can use the code review feature to ensure the code quality of tasks and prevent task execution errors caused by invalid task code. If you enable the code review feature, the task code that is committed can be deployed only after the task code passes the code review. For more information, see Code review.
If you use a workspace in standard mode, you must deploy the task in the production environment after you commit the task. To deploy a task on a node, click Deploy in the upper-right corner of the configuration tab of the node. For more information, see Deploy tasks.
What to do next
Task O&M: After you commit and deploy the task, the task is periodically run based on the scheduling configurations. You can click Operation Center in the upper-right corner of the configuration tab of the corresponding node to go to Operation Center and view the scheduling status of the task. For more information, see View and manage auto triggered tasks.