Exam AZ-220 topic 4 question 6 discussion

answers are: - No. the function has a 24h tumbling window, but that doesn’t mean ot starts at midnight. it can start any time. - No - No. see first answer. a restart will just kick off tumbling windows from that moment. first and last points hang together. yes-no or no-yes are impossible.

-NO -NO -YES

Yes/No/No I was confused by the wording. 'function' relates to the output calling a function, not to the execution of the query. Once I got this, it seems the given Answers are correct except the last one which shouldn't happen. Yes: function will be invoked when the time window ends, so at midnight. No: function should not be called for a time window still open, nor for previous data as we are streaming No: as during the day the window isn't closed, there should be no output. Hope we will find out someday which answer is right :)

1. NO - Tumbling Window's end time is inclusive by default, so any data from midnight will need to be included in the last window. Meaning the earliest possible function invocation is 00:01, possibly even later after accounting for processing time. The event timestamp will be at midnight, but the function will not be invoked at midnight. 2. YES - As far as I know, no output data will be generated if there is no input data for the window. 3. NO - The job could run many times. The number of run times will depend on what the job start time was set to and the amount of time remaining in the day. The default job start time is when you press the Start button. If the job is started soon after midnight, the function will be executed 23 times during that day (24 times per day thereafter).

I believe answers are YES - YES - YES. 1. Invoked at midnight: unlike mentioned in other responses, tumbling window function is executed at the end of the window. Executing query in image from docs (https://docs.microsoft.com/en-us/stream-analytics-query/tumbling-window-azure-stream-analytics) will return midnight as execution time (the System.Timestamp value). No matter when you start the function. 2. Invoked only when telemetry is received: if you choose a query with tumbling window less than the time property difference between messages, no record output is generated. So as long as there is no telemetry data coming in, no result from window is generated. 3. If you restart a function from last time it was stopped, it will catch up on all the queued data. The window duration affects the timestamp property, so not current time clock

Not sure about the invoked at midnight one. I would guess tumbling windows start at the moment they are defined, not at the start of the day.