GROUP BY, JOINs (medium)
Out loud, in order: clarify, build it, check it, explain it.
Practise SQLLoadingone moment…
Data engineering interview · Commerce, Travel & Marketplaces
Live SQL+Python, data modeling for high-volume (MPP/Hive), and a case study + 1-week project with architecture diagrams.
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And what its data engineers work with.
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Stages in the order candidates meet them.
6 stages. 4 rounds have reported questions, described below.
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The topics it covers and the questions candidates reported.
2 reported questions. See them below
1 reported question. See them below
3 reported questions. See them below
signature
Medium confidence1 reported question. See them below
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By round. Questions marked Expected are written from the company's standards.
SQLMedium confidence
PythonMedium confidence
Data Modeling / ArchitectureMedium confidence
Case study + 1-week projectMedium confidence
Nobody reported these exact questions at Wayfair. They are the questions a loop for each of its top topics is known to ask, so prepare for them as likely, not as confirmed.
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Ranked by how much of the evidence points at each topic.
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Do the first group before the second.
Data modeling for high-volume (MPP/Hive) + full architecture/ETL explanation with diagrams
Do first (3)SQL (GROUP BY, JOIN, window)
The case study + 1-week project (design, data quality, present clearly)
Python/Java/Scala
ThenGCP + Kafka
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Why candidates were turned down, as reported.
Weak data modeling / cannot explain full architecture + ETL choices
Modeling is named in 14 of 50 company accounts.Poor case-study/project presentation
Shaky SQL
SQL is named in 37 of 50 company accounts.08
4 reported, 1 composite. Each opens and closes. Composites are labelled.
A 60-minute first round with a SQL question and a case. The interviewer turned the camera off so the candidate could code alone.
What to take from it Be ready to code alone and talk after.
A take-home database design task. Then the candidate presented the design and wrote live queries against it.
What to take from it Design so that you can query it easily in front of people.
Candidates had to explain a complex SQL script and say what it means for the business. Then they wrote more queries when a team member asked for changes.
What to take from it Practise saying what a query tells the business.
Business cases: spot what is wrong with a metric, and explain a profit spike. One candidate also got an open design question about improving search. Round counts range from three to five.
What to take from it Practise checking a metric before you trust it.
Composite walkthroughs. Built from the company's documented loop, not from one person's account.
This is a composite, not one person's account. It follows what candidates describe: a coding test, live SQL and Python, a case study, a one-week project (data model, pipeline and ETL with an architecture diagram) and a final round with behavioral and technical parts.
What to take from it Use it as a map. The project week is the unusual part.
Invest in the 1-week project + architecture storytelling; data modeling is the core.
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Their reported questions, one at a time, against a stopwatch.
GROUP BY, JOINs (medium)
Out loud, in order: clarify, build it, check it, explain it.
Practise SQL10
Pick your level and the weeks you have.
Built from what Wayfair asks, strongest first. For the wider basics at your level, follow the Mid level plan alongside it.
Data modeling
Read: Data modeling chaptersDrill: Modeling practiceSay it aloud: Data modeling questionsFull plan: Ace the modeling round
Pipeline and system design
Read: Data pipeline chaptersDrill: Pipeline practiceSay it aloud: Data pipeline questionsFull plan: Ace the pipeline round
Python and coding
Read: Python chaptersDrill: Python practiceSay it aloud: Python questionsFull plan: Ace the Python round
Cloud and tools
Rehearse the Wayfair loop
Run the question deckThen repeat your weakest topic once more.