Exam DP-200 topic 2 question 58 discussion

HOTSPOT -
You are building an Azure Stream Analytics query that will receive input data from Azure IoT Hub and write the results to Azure Blob storage.
You need to calculate the difference in readings per sensor per hour.
How should you complete the query? To answer, select the appropriate options in the answer area.
NOTE: Each correct selection is worth one point.
Hot Area:

Suggested Answer:
Box 1: LAG -
The LAG analytic operator allows one to look up a ג€previousג€ event in an event stream, within certain constraints. It is very useful for computing the rate of growth of a variable, detecting when a variable crosses a threshold, or when a condition starts or stops being true.

Box 2: LIMIT DURATION -
Example: Compute the rate of growth, per sensor:
SELECT sensorId,
growth = reading -
LAG(reading) OVER (PARTITION BY sensorId LIMIT DURATION(hour, 1))

FROM input -
Reference:
https://docs.microsoft.com/en-us/stream-analytics-query/lag-azure-stream-analytics