Thanks! Very good points. The question was more about what would a datalake offer in terms of post processingand other benefits, since I am not familiar with the technology. I have no problems implementing an efficient solution with Azure/sql/c# for the foreseeable future. Just needed some insights in a tech I'm not familiar with.

The DB, and the code that receives tha data it hosted in Azure. Data is recieved as MQTT messages by Azure IoTHub. A C# worker subsribes to the incoming messages, and stores them normalized in an Azure SQLdb.

The telemetry data are also needed later, yes.

I do not assume, I'm asking if the mqtt spec. Specify that messages is retained in the queue if the target in offline. I am perfectly aware of space and time limitations.