Creating a Flink SQL job

Updated on 2022-12-07 GMT+08:00

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This section describes how to create a Flink SQL job. You can use Flink SQLs to develop jobs to meet your service requirements. Using SQL statements simplifies logic implementation. You can edit Flink SQL statements for your job in the DLI SQL editor. This section describes how to use the SQL editor to write Flink SQL statements.

Prerequisites

You have prepared the data input and data output channels. For details, see Preparing Flink Job Data.
When you use a Flink SQL job to access other external data sources, such as OpenTSDB, HBase, Kafka, DWS, RDS, CSS, CloudTable, DCS Redis, and DDS MongoDB, you need to create a cross-source connection to connect the job running queue to the external data source.
- For details about the external data sources that can be accessed by Flink jobs, see Datasource Connection and Cross-Source Analysis.
- For details about how to create a datasource connection, see Enhanced Datasource Connections. After a datasource connection is created, you can choose More > Test Address Connectivity in the Operation column on the Queue Management page to check whether the network connection between the queue and the external data source is normal. For details, see Testing Address Connectivity.

Creating a Flink SQL Job

In the left navigation pane of the DLI management console, choose Job Management > Flink Jobs. The Flink Jobs page is displayed.
In the upper right corner of the Flink Jobs page, click Create Job.

Specify job parameters.

**Table 1** Job configuration information
Parameter	Description
Type	Set Type to Flink SQL. You will need to rewrite SQL statements to start the job.
Name	Name of a job. Enter 1 to 57 characters. Only letters, digits, hyphens (-), and underscores (_) are allowed. NOTE: The job name must be globally unique.
Description	Description of a job. It can contain up to 512 characters.
Template Name	You can select a sample template or a custom job template. For details about templates, see Flink Template Management.

Click OK to enter the Edit page.
Edit a Flink SQL job.

Enter details SQL statements in the statement editing area. For details about SQL syntax, see the Data Lake Insight SQL Syntax Reference.
Click Check Semantics.
- You can Debug or Start a job only after the semantic verification is successful.
- If verification is successful, the message "The SQL semantic verification is complete. No error." will be displayed.
- If verification fails, a red "X" mark will be displayed in front of each SQL statement that produced an error. You can move the cursor to the "X" mark to view error details and change the SQL statement as prompted.

Set job running parameters.

**Table 2** Running parameters
Parameter	Description
Queue	A shared queue is selected by default. You can select a custom queue as needed. NOTE: During job creation, a sub-user can only select a queue that has been allocated to the user. If the remaining capacity of the selected queue cannot meet the job requirements, the system automatically scales up the capacity. When a queue is idle, the system automatically scales in the queue.
UDF Jar	If you selected custom queues, you need to configure this parameter. You can customize a UDF Jar file. Before you select a JAR file, upload the corresponding JAR package to the OBS bucket and choose Data Management > Package Management to create a package. For details, see Creating a Package. In SQL, you can call a user-defined function that is inserted into a JAR file.
CUs	Sum of the number of compute units and job manager CUs of DLI. One CU equals one vCPU and 4 GB. The configured number of CUs is the number of CUs required for job running and cannot exceed the number of CUs in the bound queue.
Job Manager CUs	Number of CUs of the management unit.
Parallelism	Number of Flink SQL jobs that run at the same time Properly increasing the number of parallel threads improves the overall computing capability of the job. However, the switchover overhead caused by the increase of threads must be considered. NOTE: This value cannot be greater than four times the compute units (number of CUs minus the number of job manager CUs). The priority of the number of parallel tasks on this page is lower than that set in the code.
Task Manager Configuration	Whether to set Task Manager resource parameters If this option is selected, you need to set the following parameters: CU(s) per TM: Number of resources occupied by each Task Manager. Slot(s) per TM: Number of slots contained in each Task Manager.
OBS Bucket	OBS bucket to store job logs and checkpoint information. If the selected OBS bucket is not authorized, click Authorize. NOTE: If both Enable Checkpointing and Save Job Log are selected, you only need to authorize OBS once.
Save Job Log	Whether to save the job running logs to OBS The logs are saved in the following path: Bucket name/jobs/logs/Directory starting with the job ID. To go to this path, go to the job list and click the job name. On the Run Log tab page, click the provided OBS link. CAUTION: You are advised to select this parameter. Otherwise, no run log is generated after the job is executed. If the job is abnormal, the run log cannot be obtained for fault locating. If this option is selected, you need to set the following parameters: OBS Bucket: Select an OBS bucket to store user job logs. If the selected OBS bucket is not authorized, click Authorize. NOTE: If both Enable Checkpointing and Save Job Log are selected, you only need to authorize OBS once.
Alarm Generation upon Job Exception	Whether to report job exceptions, for example, abnormal job running or exceptions due to an insufficient balance, to users via SMS or email If this option is selected, you need to set the following parameters: SMN Topic Select a user-defined SMN topic. For details about how to customize SMN topics, see Creating a Topic in the Simple Message Notification User Guide.
Enable Checkpointing	Whether to enable job snapshots. If this function is enabled, jobs can be restored based on the checkpoints. If this option is selected, you need to set the following parameters: Checkpoint Interval indicates the interval for creating checkpoints. The value ranges from 1 to 999999, and the default value is 30. Checkpoint Mode can be set to either of the following values: At least once: Events are processed at least once. Exactly once: Events are processed only once. OBS Bucket: Select an OBS bucket to store your checkpoints. If the selected OBS bucket is not authorized, click Authorize. The checkpoint path is Bucket name/jobs/checkpoint/Directory starting with the job ID. NOTE: You only need to authorize OBS once for both Enable Checkpointing and Save Job Log.
Auto Restart upon Exception	Whether to enable automatic restart. If this function is enabled, any job that has become abnormal will be automatically restarted. If this option is selected, you need to set the following parameters: Max. Retry Attempts: maximum number of retry times upon an exception. The unit is Times/hour. Unlimited: The number of retries is unlimited. Limited: The number of retries is user-defined. Restore Job from Checkpoint: This parameter is available only when Enable Checkpointing is selected.
Idle State Retention Time	Defines for how long the state of a key is retained without being updated before it is removed in GroupBy or Window. The default value is 1 hour.
Dirty Data Policy	Select a policy for processing dirty data. The following policies are supported: Ignore, Trigger a job exception, and Save. NOTE: Save indicates that the dirty data is stored to the OBS bucket selected above.
Dirty Data Dump Address	Set this parameter when Dirty Data Policy is set to Save. Click the address box to select the OBS path for storing dirty data.

(Optional) Debug parameters as required. The job debugging function is used only to verify the SQL logic and does not involve data write operations. For details, see Debugging a Flink Job.
(Optional) Set the runtime configuration as required. Set Custom Configuration to User-defined.
Click Save.
Click Start. On the displayed Start Flink Jobs page, confirm the job specifications, and click Start Now to start the job.

After the job is started, the system automatically switches to the Flink Jobs page, and the created job is displayed in the job list. You can view the job status in the Status column. After a job is successfully submitted, the job status will change from Submitting to Running. After the execution is complete, the message Completed is displayed.

If the job status is Submission failed or Running exception, the job submission failed or the job did not execute successfully. In this case, you can move the cursor over the status icon in the Status column of the job list to view the error details. You can click to copy error information. After handling the fault based on the provided information, resubmit the job.
NOTE:
Other available buttons are as follows:
- Save As: Save the created job as a new job.
- Debug: Perform job debugging. For details, see Debugging a Flink Job.
- Format: Format the SQL statements in the editing box.
- Set as Template: Set the created SQL statements as a job template.
- Theme Settings: Set the theme related parameters, including Font Size, Wrap, and Page Style.

Parent topic: Flink Job Management

Previous topic: Preparing Flink Job Data

Next topic: Creating a Flink Jar Job

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