25 Data Engineer Interview Questions & Pipeline Answers

Data Engineer Interview Questions 2026

Data engineering is the fastest-growing engineering specialty, with salaries ranging $130K-$200K. Interviews test: ETL/ELT pipeline design, data modeling, SQL proficiency, distributed computing (Spark, Flink), and cloud data platforms (Snowflake, BigQuery, Databricks).

The defining data engineering interview question: "Design a data pipeline that processes 10TB of raw data daily, transforms it, and makes it queryable in under 5 minutes." This tests your knowledge of batch vs streaming, data quality, and orchestration.

Key Topics

• SQL — Window functions, CTEs, query optimization. See SQL questions guide
• ETL/ELT — Airflow, dbt, Fivetran orchestration patterns
• Distributed Computing — Spark architecture, partitioning, shuffles
• Data Modeling — Star schema, snowflake schema, OBT (one big table)
• Data Quality — Great Expectations, dbt tests, data contracts

Related: data science interviews. Practice: AissenceAI.