I am working on an IoT analytics solution which consumes Avro formatted messages fired at an Azure IoT Hub and (hopefully) uses Stream Analytics to store messages in Data Lake and blob storage. A key requirement is the Avro containers must appear exactly the same in storage as they did when presented to the IoT Hub, for the benefit of downstream consumers.
I am running into a limitation in Stream Analytics with granular control over individual file creation. When setting up a new output stream path, I can only provide date/day and hour in the path prefix, resulting in one file for every hour instead of one file for every message received. The customer requires separate blob containers for each device and separate blobs for each event. Similarly, the Data Lake requirement dictates at least a sane naming convention that is delineated by device, with separate files for each event ingested.
Has anyone successfully configured Stream Analytics to create a new file every time it pops a message off of the input? Is this a hard product limitation?
Stream Analytics is indeed oriented for efficient processing of large streams. For your use case, you need an additional component to implement your custom logic.
Stream Analytics can output to Blob, Event Hub, Table Store or Service Bus. Another option is to use the new Iot Hub Routes to route directly to an Event Hub or a Service Bus Queue or Topic.
From there you can write an Azure Function (or, from Blob or Table Storage, a custom Data Factory activity) and use the Data Lake Store SDK to write files with the logic that you need.