written by
5000fish Team

Top 7 Interview Questions For A Data Warehouse/ETL Developer

BI Interview Questions 4 min read
DashboardFox - Data Warehouse Reporting

With big data and analytics such vital elements of so many businesses today, jobs that deal with data, either working to gather it, store it, or analyze it, are in high demand. ETL developers work with all parts of the data equation – ETL stands for “extract, transform, load.”

ETL developers must analyze the data storage needs of an organization to design a data warehousing system that meets those needs, extract the data from the disparate silos and sources within the organization and work to transform that data into a universal standard that can be loaded into the data warehouse.

If you are looking to hire an ETL developer, or a team to work on data warehousing, you may be wondering what qualities you should look for, and what kind of interview questions you should ask to determine whether the candidate has those qualities. We’ve put together a few qualities you should look for in a good ETL developer and some questions you can ask in an interview.

Qualities of a good ETL Developer

  • The ability to think analytically
  • An ability to spot patterns
  • Good communications skills
  • An understanding of several programming languages
  • Detail oriented
  • Team player
  • Willingness to learn
  • Ability to look at problems from different angles to find solutions

With so much transformation happening in the technology field all the time, a good ETL developer must be open-minded and flexible, and not so set in their ways that they are unwilling to look at new ways to achieve a task. While often the tried and true is the best option, sometimes new paths open up that are worth exploring.

Top Data Warehouse/ETL Developer Interview Questions

To determine whether the candidate for the data warehouse/ETL developer is the right one for the job, it’s important to ask the right questions in the interview. These questions involve more than education and skills – although, of course, those are important as well.

1. What is your experience in the field?

In spite of the current popularity of the term “big data” and every industry’s sudden interest in business intelligence, the data warehousing field has been around for a long time. The concept of data warehousing goes back to the 1980s, with some components dating back to the 1960s. While there are benefits to both brand-new applicants and old pros, it’s good to know what you’re working with.

2. Define (X, Y, Z) terms

This may seem like a no-brainer, but ask the applicant what ETL stands for, and what they think it means. Then ask about some standard ETL terminology – CRUD or OLAP. What is a data warehouse, and how is it different from a database? What is a virtual data warehouse? It’s not only the answers to these – and all questions, really – that are important, but how easily they answer them, demonstrating their depth of knowledge.

3. Which data mining technique would you use in a specific situation?

Offer the candidate a list of data mining techniques like clustering, associations, link analysis, and deviation detection. Then ask which one would you use for finding a relationship between two entities? This gets a little deeper into the weeds and is a test of their experience and how they might apply it in a practical situation.

4. What programming and scripting languages do you know?

Structured Query Language, or SQL, is essential for ETL, of course. Many programming languages are used, but SQL is the most reliable, and the backbone of ETL. However, other recommended languages include Python, Perl, and Bash, all of which are popular languages in ETL.

5. How Do You Handle High-Pressure Situations?

Tight deadlines are something every ETL developer is going to have to deal with at some point. Understanding how the candidate operates under pressure is a good indicator of whether this is someone you want on your team when things get tight. It can be the difference between getting the job done and having it fail.

6. Tell Us About a Situation You Wish You’d Handled Differently

This one is kind of a twist on the standard interview question, “tell us about a challenge you overcame,” but it doesn’t lend itself quite as easily to some of the rote answers candidates have practiced over the years. The answer to this question can tell you a lot about a candidate and how he or she views their sense of responsibility and ownership of a particular job, and let you know if this is someone who will make a good team player.

7. What Questions Do You Have For Us?

Always a good question to ask a candidate, it not only gives them an opportunity to find out more about the company and position, it gives you a sense of what they already know about your company, how interested they are in the position, and what they might bring to the team.

Find Your Perfect Data Warehouse/ETL Developer Today

As you can see, you’ll have to ask quite a few interview questions to figure out whether or not someone is a good fit to join your team as a data warehouse or ETL developer. It’ll be worth the effort of conducting several interviews, though, if it helps you find your ideal candidate.

Data Warehouse/ETL Developers are not cheap, and we think you should have them focused on their task, not spending a lot of time writing reports or doing tech support for business intelligence tools.

That’s where DashboardFox comes in. As a self-service BI tool, you can hook DashboardFox up to your databases or data warehouse, apply security, and let your business teams generate reports and dashboards without them needing a technical pedigree.

The right business intelligence software can make a huge difference to making any data warehouse project be successful. Consider checking out DashboardFox, our self-service BI tool, today and including it in your data analytics toolkit.

Data Warehouse ETL Developer Interview Questions SQL Queries Databases