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Calculate a 7-day moving average of orders for each city in the Swiggy database.

General/Othermedium0.2 min readPremium

**SQL**: SELECT city_id, order_date, order_count, AVG(order_count) OVER (PARTITION BY city_id ORDER BY order_date ROWS BETWEEN 6 PRECEDING AND CURRENT ROW) AS ma_7d FROM daily_orders. **Spark**: Window.partitionBy('city_id').orderBy('order_date').rowsBetween(-6, 0)....

🤖 Analyze Your Answer
Frequency
Low
Asked at 1 company
Category
243
questions in General/Other
Difficulty Split
151E|43M|49H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Swiggy
Interview Pro Tip

Pro-Move: 'We partition by city_id and use ROWS—city-level aggregation is dense; RANGE adds overhead.' Red Flag: Forgetting PARTITION BY city_id—mixing cities in one average.

Key Concepts Tested
partitionsparksqlwindow

Why This Question Matters

This medium-level General/Other question appears frequently in data engineering interviews at companies like Swiggy. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (partition, spark, sql) will help you answer variations of this question confidently.

How to Approach This

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.

Expert Answer
38 words

SQL: SELECT city_id, order_date, order_count, AVG(order_count) OVER (PARTITION BY city_id ORDER BY order_date ROWS BETWEEN 6 PRECEDING AND CURRENT ROW) AS ma_7d FROM daily_orders. Spark: Window.partitionBy('city_id').orderBy('order_date').rowsBetween(-6, 0). Best practice: Same as 472; partition by city for per-city series.

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According to DataEngPrep.tech, this is one of the most frequently asked General/Other 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.

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