To succeed in the technical and hiring manager interviews, you need to prepare deeply across a few critical domains. Garmin’s evaluation is heavily weighted toward practical application and past experience.
SQL and Data Manipulation
SQL is the foundational language for any data role, and Garmin tests it rigorously. You will be evaluated on your ability to write efficient, accurate queries to extract, transform, and analyze data. Strong performance means writing clean code quickly, explaining your logic as you type, and handling edge cases gracefully.
Be ready to go over:
- Complex Joins and Aggregations – Understanding how to combine multiple datasets and summarize information accurately.
- Window Functions – Using functions like
ROW_NUMBER(), RANK(), and LEAD()/LAG() to perform advanced analytical queries.
- Query Optimization – Identifying bottlenecks in your queries and understanding how indexes and execution plans work.
- Advanced concepts (less common) – Recursive CTEs, handling highly nested JSON data within SQL, and database-specific performance tuning.
Example questions or scenarios:
- "Given a table of user activity logs from Garmin wearables, write a query to find the top 3 most active users per region over the last 30 days."
- "How would you optimize a query that is joining two massive tables and currently timing out?"
- "Write a SQL query using CoderPad to calculate the rolling 7-day average of steps for a specific user ID."
Software Engineering Mindset
Garmin specifically looks for Data Engineers who want to work with software as well as data. This means you are evaluated not just as an ETL developer, but as a software engineer who specializes in data. Strong performance involves demonstrating a solid grasp of software development lifecycles, version control, and coding best practices.
Be ready to go over:
- Programming Fundamentals – Proficiency in Python, Java, or C++, including data structures and object-oriented programming.
- Pipeline Architecture – Designing scalable, fault-tolerant data pipelines using code rather than just UI-based tools.
- Testing and CI/CD – How you write unit tests for your data transformations and integrate your pipelines into continuous deployment workflows.
- Advanced concepts (less common) – Distributed systems design, real-time stream processing architecture, and microservices integration.
Example questions or scenarios:
- "Describe a time you had to build a custom data ingestion tool from scratch using Python."
- "How do you ensure data quality and handle errors programmatically within your pipelines?"
- "Walk me through how you would version control and deploy a complex data pipeline."
Project Deep Dive and Resume Defense
Your past work is a primary focal point during the Hiring Manager interview. Interviewers will dissect your resume to understand your actual contributions versus team achievements. Strong performance means delivering clear, structured narratives about your projects, highlighting your technical decisions, and showing a deep understanding of the business context.
Be ready to go over:
- End-to-End Ownership – Detailing a project from conception through deployment and maintenance.
- Technical Trade-offs – Explaining why you chose a specific database, framework, or architecture over alternatives.
- Impact and Metrics – Quantifying the results of your work (e.g., reduced processing time by 40%, saved $X in cloud costs).
- Advanced concepts (less common) – Managing stakeholder disagreements, pivoting architectures mid-project, and leading cross-functional technical initiatives.
Example questions or scenarios:
- "Walk me through the most complex data pipeline you listed on your resume. What were the biggest bottlenecks?"
- "Tell me about a time a project failed or didn't meet expectations. What did you learn?"
- "How did you collaborate with software engineering teams to ensure the data you needed was logged correctly?"