Azure Data Explorer IoT Hub Connection: IoT Hub System Properties only mapped to a single ingested message in a MULTIJSON message

Question

Hi, good morning.
I have developed a IoT Edge solution that allows sending messages in batches to IoT Hub. Instead of sending single json messges, I'm sending a Json array in order to reduce sending IoT Hub message number due to costs. All is working fine, and messages are arriving correctly in the IoT Hub.

But when I try to ingest these messages directly in Azure Data Explorer using IoT Hub Data Connection, I've a problem mapping Event System Properties to the messages.
As I'm using MULTIJSON format, each single message in the array is processed correctly, but the Event System Properties, for example the DeviceId, are only being mapped to a single message in the batch.

Is there a way to map these properties to all messages in the json array before storing them in ADX table.

Thank you very much.
Best regards.

Answer 1

Hi,

I don's see anything strange to your mapping. I don't know if it will work but the next thing I would try is mapping the data to a source table (maybe even with JSON format instead of the MULTIJSON) and then use update policies to resolve the data. My friend @Sander van de Velde wrote a blog about it:

https://sandervandevelde.wordpress.com/2022/07/29/using-adx-table-update-policies-projecting-raw-messages-to-target-tables/