How should I prepare for a data engineering interview? Should I focus on system design, and what topics should I study?

Start by mastering core data engineering concepts: ETL pipelines, data modeling, relational and NoSQL databases, batch vs. real‑time processing, and big‑data frameworks like Spark and Kafka. Build a small project that ingests data, transforms it, and stores it in a data warehouse. Study SQL thoroughly, including joins, window functions, and aggregation. For system design, practice designing data pipelines, data lakes, and real‑time analytics systems. Read case studies from companies like Netflix or Uber. Finally, practice coding and SQL questions, and do mock interviews to get comfortable explaining your thought process.