Resources
Every guide, practice problem, and reference on the site, organized by the decision you are trying to make. Start with your situation and follow the cards from there.
Start with your situation
Everything on the site sits under one of these. Pick the one that matches where you are today; the rest is here when you need it.
One page that walks all 5 rounds end to end. Start here if you do not yet know where a data engineering loop focuses.
2 weeks outYour query runs against a real database and either returns the rows or does not. If you have one hour, this is the highest-yield way to spend it.
Targeting a companyThe loops that bend the standard template. Round structure and what is actually asked, company by company.
The 5 rounds, walked end to end
Every data engineering loop covers these 5. Each guide covers the patterns interviewers score on and the failure modes that lose the round. Read one and the rest are in the same voice.
The largest bucket in almost every loop. Window functions, gaps-and-islands, dedup.
Data-engineering-shaped Python: parsing, transforms, ETL logic. Not LeetCode.
Grain-first schema design. Star schemas, SCDs, and defending your grain.
Pipeline architecture at scale. The round that separates senior from mid.
STAR stories that survive follow-ups. The easiest round to under-prepare.
Practice that pushes back
Real interview problems across all 5 domains, every one of them executed rather than compared to an answer key. Free, and no login to start.
Runs on a real database against randomized fixtures, which catches the shortcut that only worked on the sample rows.
Data-engineering-shaped Python, not algorithm puzzles.
DataFrame transforms and Spark SQL, executed on real inputs rather than eyeballed.
Schema design problems with grain-first rubrics.
Draw the pipeline, pick the tools, then defend it against the SLA you were handed.
Domain deep reads
The long version of each of the 5 domains, written the way you would brief a friend before their loop. Read these when you want depth rather than reps.
The patterns that recur, with 15 worked solutions.
The shapes DE Python rounds actually take.
The PySpark and Spark SQL questions loops lean on.
Schema design questions and how to reason out loud.
System design questions framed for data pipelines.
One hundred questions, weighted by how often they actually land.
Company interview guides
The loops worth knowing in advance because they bend the standard template. Round structure, what is actually asked, and where each loop deviates.
SQL- and modeling-heavy. E3 to E7 leveling.
System design depth. A second design round at senior.
Delta Lake and PySpark, with little tolerance for hand-waving.
Streaming and large-scale event processing.
Metrics and experimentation rounds.
Heavy data modeling with live schema critique.
Big-tech standard with a BigQuery dialect bias.
Leadership Principles plus an L4 to L7 technical bar.
SQL optimization and Snowflake-specific syntax.
Decisions that change where you focus
High-intent comparisons for the role-and-tool questions interviewers actually pose. Read the one that maps to a choice in front of you.
The role question, if you are deciding which lane to aim for.
The transition path. Read this one first if you are switching in.
The framing interviewers expect you to defend.
When each wins, and how to say why.
Transformation vs orchestration, and where they overlap.
The two platforms most compared in loops.
The streaming choice, with the tradeoffs that matter.
Get the boring parts right
The recruiter screen is the easiest part of the loop to win and the easiest to underestimate. These are the artifacts that decide it.
Tool references, for when you know the stack
Open these once you know a company's stack and are targeting that dialect. Most candidates over-prepare on them; loops focus on them less than the job posts suggest.
The site has more guides than you have time to read
- 01
Reading a solution is not the same as writing one
Every engineer who has frozen on a query they had read a dozen times knows the gap. The only preparation that closes it is producing the answer yourself, under time, before the interview does it for you
- 02
76% of hiring managers reject on the coding task, not the resume
From HackerRank's 2024 Developer Skills Report. Candidates who look strong on paper still fail the live screen if they haven't done timed, executable practice
- 03
System design comes down to the calls you defend out loud
Ingestion, batch vs streaming, the bronze/silver/gold layers, idempotency, backfill and replay. Sketching the pipeline and naming the failure modes is the signal, not the boxes