**Tumbling windows**: Fixed, non-overlapping intervals. Each batch processes one complete window; no overlap = each record in exactly one batch. **Trigger**: Fires when window completes (e.g., watermark passes window end). **Consistency**: Exactly-once or at-least-once per...
This medium-level SQL question appears frequently in data engineering interviews at companies like Virtusa. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (window) will help you answer variations of this question confidently.
Break this problem into components. Identify the core trade-offs involved, then walk the interviewer through your reasoning step by step. Demonstrate awareness of edge cases and production considerations - this is what separates good answers from great ones.
Tumbling windows: Fixed, non-overlapping intervals. Each batch processes one complete window; no overlap = each record in exactly one batch. Trigger: Fires when window completes (e.g., watermark passes window end). Consistency: Exactly-once or at-least-once per window; idempotent sink replays safely. Allowed lateness: Buffer for late events; emit final when watermark + lateness passed.
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Analyze My Answer — FreeAccording to DataEngPrep.tech, this is one of the most frequently asked SQL interview questions, reported at 1 company. DataEngPrep.tech maintains a curated database of 1,863+ real data engineering interview questions across 7 categories, verified by industry professionals.