Data · 2026 Guide
Data Engineer Interview Questions
Data Engineer interviews focus on SQL mastery, batch/stream processing, warehousing, and pipeline design. Expect 1–2 SQL rounds, 1 system design (data pipeline), and behavioral.
Core Interview Topics
Data Engineer interviews at top tech companies typically assess these competency areas:
Top 10 Data Engineer Interview Questions
These questions are drawn from real interview loops at FAANG and top-tier tech companies in 2025–2026. Click Practice now to run a full AI mock session for any question.
- 1
Design a pipeline to ingest 1TB/day of clickstream into a warehouse.
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Write SQL to compute 7-day rolling DAU from event logs.
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Star vs snowflake schema — when do you use which?
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Explain partitioning, bucketing, and clustering in BigQuery.
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Build a slowly-changing dimension type 2 table from scratch.
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How do you guarantee exactly-once semantics in a Kafka → Spark pipeline?
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Diagnose a slow Airflow DAG that ran fine last week.
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Compare batch vs micro-batch vs streaming for a fraud-detection use case.
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How do you do data quality testing? Great Expectations, dbt tests, custom?
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Cost-optimize a Snowflake warehouse running $40k/month.
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How to Prepare
- ✓Be fluent in window functions and CTEs — every interview has SQL.
- ✓Do a Spark or Flink mini-project end-to-end.
- ✓Know dbt — it's the modern analytics-engineering standard.
- ✓Practice diagramming pipelines on a whiteboard.
ATS Resume Keywords
Include these high-signal keywords in your Data Engineer resume to pass ATS filters at top companies.
Resume must-haves for Data Engineer:
- Pipeline scale numbers (TB/day, rows/sec)
- Cost savings
- SLA / freshness targets met
- Warehouse + orchestrator named