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Queries for IoT Hub jobs

  • Artikkel

Jobs provide a way to execute operations on sets of devices. Each device twin contains the information of the jobs that target it in a collection called jobs. IoT Hub enables you to query jobs as a single JSON document containing all twin information.

Here's a sample IoT hub device twin that is part of a job called myJobId:

{
    "deviceId": "myDeviceId",
    "etag": "AAAAAAAAAAc=",
    "tags": {
        ...
    },
    "properties": {
        ...
    },
    "jobs": [
        {
            "deviceId": "myDeviceId",
            "jobId": "myJobId",
            "jobType": "scheduleUpdateTwin",
            "status": "completed",
            "startTimeUtc": "2016-09-29T18:18:52.7418462",
            "endTimeUtc": "2016-09-29T18:20:52.7418462",
            "createdDateTimeUtc": "2016-09-29T18:18:56.7787107Z",
            "lastUpdatedDateTimeUtc": "2016-09-29T18:18:56.8894408Z",
            "outcome": {
                "deviceMethodResponse": null
            }
        },
        ...
    ]
}

Currently, this collection is queryable as devices.jobs in the IoT Hub query language.

Important

Currently, the jobs property is not returned when querying device twins. That is, queries that contain FROM devices. The jobs property can only be accessed directly with queries using FROM devices.jobs.

For example, the following query returns all jobs (past and scheduled) that affect a single device:

SELECT * FROM devices.jobs
  WHERE devices.jobs.deviceId = 'myDeviceId'

Note how this query provides the device-specific status (and possibly the direct method response) of each job returned.

It's also possible to filter with arbitrary Boolean conditions on all object properties in the devices.jobs collection.

For example, the following query retrieves all completed device twin update jobs that were created after September 2016 for a specific device:

SELECT * FROM devices.jobs
  WHERE devices.jobs.deviceId = 'myDeviceId'
    AND devices.jobs.jobType = 'scheduleUpdateTwin'
    AND devices.jobs.status = 'completed'
    AND devices.jobs.createdTimeUtc > '2016-09-01'

You can also retrieve the per-device outcomes of a single job.

SELECT * FROM devices.jobs
  WHERE devices.jobs.jobId = 'myJobId'

Jobs query limitations

Query expressions can have a maximum length of 8192 characters.

Currently, queries on devices.jobs don't support:

  • Projections, therefore only SELECT * is possible.
  • Conditions that refer to the device twin in addition to job properties (see the preceding section).
  • Aggregations, such as count, avg, and group by.

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