✅ 15 Data Engineering Interview Questions for Freshers 🛠️📊
These are core questions freshers face in 2025 interviews—per recent guides from DataCamp and GeeksforGeeks, ETL and pipelines remain staples, with added emphasis on cloud tools like AWS Glue for scalability. Your list nails the basics; practice explaining with real examples to shine!
1) What is Data Engineering?
Answer: Data Engineering involves designing, building, and managing systems and pipelines that collect, store, and process large volumes of data efficiently.
2) What is ETL?
Answer: ETL stands for Extract, Transform, Load — a process to extract data from sources, transform it into usable formats, and load it into a data warehouse or database.
3) Difference between ETL and ELT?
Answer: ETL transforms data before loading it; ELT loads raw data first, then transforms it inside the destination system.
4) What are Data Lakes and Data Warehouses?
Answer:
⦁ Data Lake: Stores raw, unstructured or structured data at scale.
⦁ Data Warehouse: Stores processed, structured data optimized for analytics.
5) What is a pipeline in Data Engineering?
Answer: A series of automated steps that move and transform data from source to destination.
6) What tools are commonly used in Data Engineering?
Answer: Apache Spark, Hadoop, Airflow, Kafka, SQL, Python, AWS Glue, Google BigQuery, etc.
7) What is Apache Kafka used for?
Answer: Kafka is a distributed event streaming platform used for real-time data pipelines and streaming apps.
8) What is the role of a Data Engineer?
Answer: To build reliable data pipelines, ensure data quality, optimize storage, and support data analytics teams.
9) What is schema-on-read vs schema-on-write?
Answer:
⦁ Schema-on-write: Data is structured when written (used in data warehouses).
⦁ Schema-on-read: Data is structured only when read (used in data lakes).
10) What are partitions in big data?
Answer: Partitioning splits data into parts based on keys (like date) to improve query performance.
11) How do you ensure data quality?
Answer: Data validation, cleansing, monitoring pipelines, and using checks for duplicates, nulls, or inconsistencies.
12) What is Apache Airflow?
Answer: An open-source workflow scheduler to programmatically author, schedule, and monitor data pipelines.
13) What is the difference between batch processing and stream processing?
Answer:
⦁ Batch: Processing large data chunks at intervals.
⦁ Stream: Processing data continuously in real-time.
14) What is data lineage?
Answer: Tracking the origin, movement, and transformation history of data through the pipeline.
15) How do you optimize data pipelines?
Answer: By parallelizing tasks, minimizing data movement, caching intermediate results, and monitoring resource usage.
💬 React ❤️ for more!
These are core questions freshers face in 2025 interviews—per recent guides from DataCamp and GeeksforGeeks, ETL and pipelines remain staples, with added emphasis on cloud tools like AWS Glue for scalability. Your list nails the basics; practice explaining with real examples to shine!
1) What is Data Engineering?
Answer: Data Engineering involves designing, building, and managing systems and pipelines that collect, store, and process large volumes of data efficiently.
2) What is ETL?
Answer: ETL stands for Extract, Transform, Load — a process to extract data from sources, transform it into usable formats, and load it into a data warehouse or database.
3) Difference between ETL and ELT?
Answer: ETL transforms data before loading it; ELT loads raw data first, then transforms it inside the destination system.
4) What are Data Lakes and Data Warehouses?
Answer:
⦁ Data Lake: Stores raw, unstructured or structured data at scale.
⦁ Data Warehouse: Stores processed, structured data optimized for analytics.
5) What is a pipeline in Data Engineering?
Answer: A series of automated steps that move and transform data from source to destination.
6) What tools are commonly used in Data Engineering?
Answer: Apache Spark, Hadoop, Airflow, Kafka, SQL, Python, AWS Glue, Google BigQuery, etc.
7) What is Apache Kafka used for?
Answer: Kafka is a distributed event streaming platform used for real-time data pipelines and streaming apps.
8) What is the role of a Data Engineer?
Answer: To build reliable data pipelines, ensure data quality, optimize storage, and support data analytics teams.
9) What is schema-on-read vs schema-on-write?
Answer:
⦁ Schema-on-write: Data is structured when written (used in data warehouses).
⦁ Schema-on-read: Data is structured only when read (used in data lakes).
10) What are partitions in big data?
Answer: Partitioning splits data into parts based on keys (like date) to improve query performance.
11) How do you ensure data quality?
Answer: Data validation, cleansing, monitoring pipelines, and using checks for duplicates, nulls, or inconsistencies.
12) What is Apache Airflow?
Answer: An open-source workflow scheduler to programmatically author, schedule, and monitor data pipelines.
13) What is the difference between batch processing and stream processing?
Answer:
⦁ Batch: Processing large data chunks at intervals.
⦁ Stream: Processing data continuously in real-time.
14) What is data lineage?
Answer: Tracking the origin, movement, and transformation history of data through the pipeline.
15) How do you optimize data pipelines?
Answer: By parallelizing tasks, minimizing data movement, caching intermediate results, and monitoring resource usage.
💬 React ❤️ for more!
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