Data Engineering Interview Preparation #2: DuckDB SQL, Data Quality and Parquet
Summary : Practice SQL for data engineering with DuckDB and a small network-traffic dataset. This hands-on example covers table creation, filtering, joins, aggregations, window functions, Pandas and SQL result checks, data-quality rules, and a Parquet round trip. SQL is a core tool for data engineers. It helps us explore source data, transform records, build analytical datasets, and check whether pipeline outputs are correct. You do not need to set up a separate database server to practice these patterns. With DuckDB, you can run analytical SQL directly from Python in a Kaggle notebook. In this exercise, we use a small CSV containing network events. Each row includes a timestamp, source IP, destination IP, port, protocol, bytes sent, and event duration. The goal is not just to write queries, but to follow a simple engineering workflow: ingest the data, inspect it, transform it, validate it, and save a verified output. Run the hands-on notebook: Data Engineering Interview Prepara...