D8LooP · Interview preparation
Prepare for the Data Engineering interview.
It is four interviews wearing one job title. Know which one you are in, and what it is scored on.
1203 answered questions50 companies, round by round17 staged plans2 studios, no account
01
The six rounds
Nearly every data engineering company runs this same loop, in this order. Only the names on it change.
02
Interview questions, by subject
1203 of them. Each one carries the answer, the answer that gets you rejected, and the follow-up they ask next.
- 130SQLquestions
- 119Pythonquestions
- 110Data Modelingquestions
- 119Data Pipelinequestions
- 120Apache Sparkquestions
- 100dbtquestions
- 102Airflowquestions
- 50Apache Kafkaquestions
- 50Lakehouse Table Formatsquestions
- 50AWSquestions
- 50GCPquestions
- 50Azurequestions
- 105Data Processing Algorithmsquestions
- 48Behavioralquestions
03
50 companies, round by round
The questions candidates were actually asked — and what got people rejected.
04
Or follow a plan
17 staged plans. Every step is a chapter or a reviewed exercise that already ships — and it ticks itself off as you go.
Build Your Foundation
Interviewing
- Data Engineer · 2–4 yearsYou can pass the SQL, Python, modeling, design, Spark and behavioral rounds at mid-level.
- Senior Data Engineer · 5–8 yearsYou lead a design, defend one model, and tell ownership stories with real stakes.
- Staff Data Engineer · 8+ yearsYou show org-scope impact: designs other teams depend on, and stories with numbers.
- Ace the SQL roundYou can take a vague prompt to a defended answer and explain the cost.
- Ace the Python roundYou can transform a real dataset, defend the edge cases, and be reviewed.
- Ace the Data Pipeline roundYou can design a pipeline and defend the reruns, the late data and the cost.
- Ace the Data Modelling roundYou can design a model from a vague prompt and defend every choice in it.
- Ace the Spark roundYou can narrate any Spark job from its plan, and fix it with evidence.
- Senior / staff depthYou argue cost, failure and change without being asked to.
- Interview in 3 weeksYou can pass a SQL screen, survive the Spark round, and defend a design out loud.
Hands on Concepts
- Design the warehouseYou own a model that loads nightly and that other teams trust.
- Real-time & streamingYou can run a stream in production and explain what it guarantees.
- Own the on-call pagerYou can take the pager and give the numbers back without a second incident.
- Make Spark jobs fastYou can make a slow Spark job cheaper and prove the answer did not change.
05
Try it yourself
You do not learn to design a system by reading about one. So you build it, submit it, and defend it — the way the round itself works.
- 01BuildOn the canvas. Entities, keys, grain — your decisions, not a multiple choice.
- 02SubmitOne click. No account, no card, no trial clock.
- 03ReviewScored on named axes and told what a senior engineer would have asked next.