Data Engineering interview questions
500 questions with model answers, in four levels. Start with Basic, check yourself honestly, then move up.
Basic questions
- SQL Fundamentals (13)
- Advanced SQL & Query Optimization (13)
- Data Modeling (13)
- Relational & NoSQL Databases (13)
- Data Warehousing (13)
- ETL/ELT & Orchestration (13)
- Apache Spark & Big Data (12)
- Streaming (Kafka, Flink, Spark Streaming) (12)
- Data Lakes & Lakehouse (Delta, Iceberg, Hudi) (12)
- Cloud Data Platforms (AWS, Azure, GCP, Snowflake, Databricks) (12)
- Data Quality, Governance & Security (12)
- Python, Pipeline Design & Cost Optimization (12)
Intermediate questions
- SQL Fundamentals (13)
- Advanced SQL & Query Optimization (13)
- Data Modeling (13)
- Relational & NoSQL Databases (13)
- Data Warehousing (13)
- ETL/ELT & Orchestration (13)
- Apache Spark & Big Data (12)
- Streaming (Kafka, Flink, Spark Streaming) (12)
- Data Lakes & Lakehouse (Delta, Iceberg, Hudi) (12)
- Cloud Data Platforms (AWS, Azure, GCP, Snowflake, Databricks) (12)
- Data Quality, Governance & Security (12)
- Python, Pipeline Design & Cost Optimization (12)
Advanced questions
- SQL Fundamentals (11)
- Advanced SQL & Query Optimization (11)
- Data Modeling (11)
- Relational & NoSQL Databases (11)
- Data Warehousing (11)
- ETL/ELT & Orchestration (10)
- Apache Spark & Big Data (10)
- Streaming (Kafka, Flink, Spark Streaming) (10)
- Data Lakes & Lakehouse (Delta, Iceberg, Hudi) (10)
- Cloud Data Platforms (AWS, Azure, GCP, Snowflake, Databricks) (10)
- Data Quality, Governance & Security (10)
- Python, Pipeline Design & Cost Optimization (10)
Tricky questions
- SQL Fundamentals (7)
- Advanced SQL & Query Optimization (7)
- Data Modeling (7)
- Relational & NoSQL Databases (6)
- Data Warehousing (6)
- ETL/ELT & Orchestration (6)
- Apache Spark & Big Data (6)
- Streaming (Kafka, Flink, Spark Streaming) (6)
- Data Lakes & Lakehouse (Delta, Iceberg, Hudi) (6)
- Cloud Data Platforms (AWS, Azure, GCP, Snowflake, Databricks) (6)
- Data Quality, Governance & Security (6)
- Python, Pipeline Design & Cost Optimization (6)
Sample questions
- What is SQL?
- What does COALESCE do?
- What is a time-series database?
- What is XCom in Airflow?
- How does Kafka retain data?
- What is Amazon EMR?
- Write a query to find employees who earn more than their managers.
- How do you upsert with MERGE?
- Why use connection pooling?
- How does a high-water-mark incremental extract work?
- How do you join a stream with a slowly changing reference table?
- What is Delta Sharing or secure data sharing in Snowflake?
- Write a query to find users whose first purchase happened within 7 days of sign-up.
- How would you model data for both historical accuracy and current reporting?
- How do you manage warehouse workloads so ETL doesn't slow down BI users?
- How would you design a real-time fraud detection pipeline?
- How would you migrate data between cloud providers?
- Does WHERE column = NULL find rows with missing values?
- Does eventual consistency mean data may never become consistent?
- Is lower latency always worth it in data pipelines?