Answer: Hopping

## Window Function Analysis for Azure Stream Analytics ### Requirements Analysis: - **Window Size**: 5 minutes (last five minutes of data) - **Output Frequency**: Every minute - **Function**: Count of records ### Window Function Comparison: #### **Hopping Window (Correct Choice)** - **Definition**: A hopping window model that moves forward in time by a fixed period (hop size) and has a fixed duration (window size). - **Why it fits**: - Window size = 5 minutes (captures last 5 minutes of data) - Hop size = 1 minute (outputs every minute) - Syntax: `HOPPINGWINDOW(minute, 5, 1)` - Each window overlaps with previous windows, creating the "last 5 minutes every minute" behavior - Windows are aligned to clock time boundaries #### **Tumbling Window (Incorrect)** - **Definition**: Non-overlapping, contiguous time windows - **Why it doesn't fit**: - Windows don't overlap - Would output counts every 5 minutes, not every minute - Cannot achieve "last 5 minutes every minute" requirement #### **Sliding Window (Incorrect)** - **Definition**: Outputs events when events occur, with windows that slide continuously - **Why it doesn't fit**: - Only outputs when events are present in the window - May not produce output every minute if no new events arrive - Not aligned to fixed time intervals - Less predictable output frequency #### **Session Window (Incorrect)** - **Definition**: Groups events that occur close together in time, separated by gaps of inactivity - **Why it doesn't fit**: - Window boundaries are event-driven, not time-based - Cannot guarantee output every minute - Window sizes vary based on data patterns ### Key Technical Justification: The hopping window is specifically designed for scenarios requiring **regular, periodic outputs of overlapping time windows**. The combination of a 5-minute window size with a 1-minute hop size perfectly matches the requirement to "count records from the last five minutes every minute." Each output represents a complete 5-minute window that advances by 1 minute for each subsequent output, creating the overlapping coverage needed.

Author: LeetQuiz Editorial Team