Medium-level system design questions from real data engineering interviews.
These medium system design questions are selected from real interviews at top companies. Each question includes a detailed expert answer and pro tip to help you nail your interview. This set leans toward the medium-difficulty band most real interviews actually live in (6 of 6). Recurring themes are partition, join, and snowflake — these patterns appear most often in real interviews and reward the deepest preparation. These questions have been reported across 5 companies including Swiggy and Capco. Average answer is around 1 minute of reading — plan roughly 1 hour to work through the full set thoughtfully.
This collection contains 6 curated questions: 0 easy, 6 medium. The balanced mix of difficulties makes this set suitable for engineers at any career stage.
The most frequently tested areas in this set are partition (4), join (2), snowflake (2), spark (2), window (2), and sql (1). Focusing on these topics will give you the highest return on your preparation time.
Medium-difficulty questions form the bulk of real interviews — spend the most time here and practice explaining your reasoning out loud. For each question, try answering before revealing the solution. Use our AI Mock Interview to simulate real interview conditions and get instant feedback on your responses.
Describe a scenario where you had to optimize a slow-running data pipeline.
How would you monitor and reduce disk-based queries (disk spilling)?
What are the best practices for logging and monitoring bad data?
What are the limitations of Assert Transformations in complex data flows?
How do you ensure the scalability of a data pipeline handling rapidly growing data volumes?
How do you handle pipeline failures or delays?
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