Wayfair Data Engineer Interview Questions + Guide in 2024

Wayfair is one of the world’s largest online destinations for home goods, offering a vast selection of furniture and decor. Known for its commitment to industry-leading technology and creative problem-solving, Wayfair is continually pushing the boundaries of eCommerce.

As a Data Engineer at Wayfair, you’ll be crucial in shaping the data engineering team’s roadmap and deliverables. The role requires collaboration with data scientists, analysts, application teams, and other data engineering squads. You’ll work with cutting-edge technologies to build and optimize data models, pipelines, and products that directly impact Wayfair’s millions of daily customers.

Thinking about joining Wayfair? This guide, hosted by Interview Query, walks you through the interview process, common Wayfair data engineer interview questions, and tips for success. Let’s get started!

The interview process usually depends on the role and seniority; however, you can expect the following on a Wayfair data engineer interview:

Recruiter/Hiring Manager Call Screening

If your CV is among the shortlisted few, a recruiter from the Wayfair Talent Acquisition Team will contact you and verify key details like your experiences and skill level. Behavioral questions may also be part of the screening process.

During this call, the recruiter gathers details about your current role and assesses if you are a good fit for the position. If everything goes well, you will be forwarded for the next round of interviews.

Technical Virtual Interview

Successfully navigating the recruiter round will result in an invitation for the technical screening round. This usually involves a virtual Codility test, assessing your experience with MPP data systems, Big Data, and pipelines. You will be given SQL and Python questions to solve.

The technical screening also includes live coding and business cases where you must find what’s wrong with certain data behavior. Following this, you might face questions regarding streaming architecture and analytics stacks, especially regarding GCP.

A typical setup is a virtual interview that lasts about an hour, with questions centered on SQL queries, data modeling, and ETL pipeline designs.

Onsite Interview Rounds

After completing the technical screen, you will be invited to attend the onsite interview loop. The onsite loop at Wayfair consists of multiple stages, including:

1. Coding Test: This may involve SQL and Python coding tasks.
2. Case Study Presentation: Discuss a specific case study where you solve a given problem.
3. Project Presentation: Discuss a project you’ve worked on, highlighting your technical choices and outcomes.
4. Behavioral and Technical Interview: This round will include traditional behavioral questions and detailed technical questions specific to Wayfair’s business.

Homework Assignment

If you pass the on-site rounds, you may be given a homework assignment involving system design and coding tasks. You will design solutions for batch and streaming data, and this homework will be reviewed in a follow-up interview.

Typically, interviews at Wayfair vary by role and team, but commonly, Data Engineer interviews follow a fairly standardized process across these question topics.

1. Is sending a huge email blast to the entire customer list a good idea? Why or why not?

You are a data scientist for a B2B SAAS business that misses revenue expectations by 10%. An executive suggests sending a massive email blast to all customers to boost sales. Evaluate if this is a good strategy and explain your reasoning.

2. Should the sales team target individual companies or groups of companies for white pages and marketing blog content?

The sales team wants to attract new customers by creating white pages and marketing blog content. Determine whether they should focus on individual or group companies and justify your recommendation.

3. What business-relevant hypotheses can be checked based on stock-out metrics for each company?

You have a table with out-of-stock inventory data, including date, country, company, product, and stock-out status. Calculate metrics for each company: completely free of stock-outs, stock-out in only one country, and stock-outs in multiple countries simultaneously. Propose business-relevant hypotheses to test based on these metrics and observed results.

4. How would you analyze transaction data to understand revenue loss in an e-commerce company?

An e-commerce company has seen a decline in revenue over the past 12 months. You have transaction data, including date of sale, total amount paid, profit margin per unit, quantity, item category, item subcategory, marketing attribution source, and discount applied. Describe how you would analyze this dataset to pinpoint where the revenue loss is occurring.

5. Write a function closest_key to find the key with the input value closest to the beginning of the list.

Given a dictionary with keys of letters and values of a list of letters, write a function closest_key to find the key with the input value closest to the beginning of the list.

6. Write a query to determine how many users have opened an email.

Given a table called events that keeps track of every user’s actions, write a query to determine how many users have opened an email.

7. How would you design a YouTube video recommendation system?

You are tasked with building the YouTube video recommendation algorithm. How would you design the recommendation system, and what important factors should you consider when building it?

8. What is the expected number of good ads rated by different types of raters?

1. Suppose we have 100 raters, each rating one ad independently. What’s the expected number of good ads?
2. Now, suppose we have 1 rater rating 100 ads. What’s the expected number of good ads?
3. Suppose we have 1 ad rated as bad. What’s the probability the rater was lazy?

9. Write a function to simulate coin tosses with a given probability of heads.

Create a function that takes the number of tosses and the probability of heads as inputs. The function should return a list of randomly generated results (‘H’ for heads and ’T’ for tails) equal in length to the number of tosses.

Example 1:

tosses = 5
probability_of_heads = 0.6

Output:

coin_toss(tosses, probability_of_heads) -> ['H', 'T', 'H', 'H', 'T']

Example 2:

tosses = 3
probability_of_heads = 0.2

Output:

coin_toss(tosses, probability_of_heads) -> ['T', 'T', 'T']

10. Write a function to calculate the sample variance of a list of integers.

Create a function that takes a list of integers as input and returns the sample variance, rounded to 2 decimal places.

Example:

test_list = [6, 7, 3, 9, 10, 15]

Output:

get_variance(test_list) -> 13.89

11. What is the probability of rolling at least one 3 with dice?

1. What’s the probability of rolling at least one 3 with 2 dice?
2. What’s the probability of rolling at least one 3 given (N) dice?

12. What is the probability of finding an item on Amazon’s website given its availability in warehouses?

Given that the probability of item X being available at warehouse A is 0.6 and at warehouse B is 0.8, what is the probability that item X would be found on Amazon’s website?

Here are some quick tips on how you can ace your Wayfair data engineer interview:

1. Familiarize with Data Engineering Concepts: Wayfair’s data engineering interviews focus greatly on cloud data platforms, especially GCP, and real-time data streaming tools like Kafka. Make sure you understand these technologies thoroughly.

2. Prepare for Behavioral Questions: Behavioral questions aim to understand your past experiences and how you handle various scenarios. Be prepared with specific examples of convincing someone, recent projects, and learning new technologies.

3. Practice System Design: Many rounds will involve designing data models, pipelines, and ETL processes. Practice drawing detailed architecture diagrams, and be prepared to explain your reasoning and choices thoroughly.

What is the average salary for a Data Engineer at Wayfair?

What skills are essential for a Data Engineer position at Wayfair?

To succeed as a Data Engineer at Wayfair, you should have expertise with big data technologies such as Hadoop, Spark, Hive, and Presto. A strong understanding of cloud platforms like GCP, deploying data warehousing solutions like Big Query, along with proficiency in object-oriented or scripting languages like Python, Java, or Scala, and SQL is crucial. Experience with real-time data streaming tools like Kafka and building data models for traditional relational databases or big data stores is also essential.

What can I expect from the work environment at Wayfair?

Wayfair prides itself on a supportive, flexible work environment that balances personal and professional commitments. The company values creativity, collaboration, and diversity. It encourages risk-taking, iterative learning, and leveraging big data to drive business insights. The team focuses on solving big business problems with cutting-edge technology.

What benefits does Wayfair offer to its employees?

Wayfair offers a comprehensive package of paid holidays, paid time off (PTO), full health benefits (Medical, Dental, Vision, HSA/FSA), and mental health support. Employees also enjoy financial growth opportunities with 401K matching, tuition reimbursement, and tax-advantaged accounts. Unique perks include employee discounts, fitness discounts, and a supportive work-life balance.

Wayfair offers diverse opportunities to work with large-scale data, leverage cutting-edge technologies, and impact millions of customers daily. If you’re aiming for a Data Engineer position at Wayfair, you’re in for an exciting journey combining technical skill and strategic influence.

Preparation is key to maximizing your chances of success. For comprehensive insights and preparation tips, check out our Wayfair Interview Guide. Here, you’ll find detailed coverage of potential interview questions and expectations. Additionally, explore our other role-specific guides such as software engineer and data analyst to gain a holistic understanding of Wayfair’s hiring process.

Best of luck with your interview! If you have any questions, don’t hesitate to reach out. Dive in, prepare well, and take the next step toward your exciting career at Wayfair!