Data Engineer Interview Questions
Practice 140 real Data Engineer interview questions for 2026. Covers companies like Meta, TikTok, Rbcroyalbank, Capital One, and Amazon — real Data Engineer interview questions from actual interviews with detailed solutions to help your interview preparation. Expect the loop to emphasize production-grade SQL, scalable ETL and pipeline design, distributed-processing tooling (Spark/Kafka), data modeling for analytics and OLAP, and data-quality/observability trade-offs alongside behavioral and product-sense conversations tied to metrics. What’s distinctive: hiring teams now prioritize shipping reliable pipelines and diagnosing failures in production over pure algorithmic puzzles, so you’ll be evaluated on writing efficient windowed SQL, designing fault-tolerant pipelines, choosing storage and partitioning strategies, and explaining trade-offs around latency, cost, and observability. To prepare, practice timed SQL and Python exercises, sketch end-to-end pipeline designs with concrete components (Airflow, Kafka, S3/BigQuery/Redshift), rehearse STAR stories about ownership and incident response, and run mock interviews that simulate debugging a broken pipeline under time pressure.

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"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."

"I honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."

"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."

"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Deep-dive XGBoost handling and overfitting
Technical / ML Deep Dive You used gradient-boosted decision trees (e.g., XGBoost/LightGBM) for a credit risk or response prediction problem. Answer th...
Write SQL for app metrics
You are given a simplified schema for a photo-sharing app: - users(user_id, user_name, joined_at) - photos(photo_id, user_id, created_at) - follows(fo...
Design a schema for server engagement
You are building analytics for a chat platform similar to Discord. The raw event sources are: - server(server_id, creator_id, created_at) - server_vie...
Design batch and streaming ETL architecture
System Design: End-to-End Data Platform for Product Analytics (Batch + Near-Real-Time) Context Design a scalable data platform for a large consumer pr...
Discuss Challenges and Career Goals
Answer the following behavioral interview questions: 1. What was the most difficult problem you have faced in your work, and how did you approach it? ...
Connect Points With Minimum Total Distance
You are given an array points, where points[i] = [xi, yi] represents a point on a 2D plane. The cost to connect two points i and j is their Manhattan ...
Describe past NLP work and collaboration
Scenario In an initial phone screen, the interviewer asks you to introduce yourself, then drills into your resume. Questions (answer using concrete ex...
Answer conflict and ambiguity with STAR stories
Job Fit / Behavioral: STAR Stories Prepare answers using the STAR (Situation, Task, Action, Result) format for the following prompts: 1. Tell me about...
Answer Amazon Behavioral Questions
Question You are in the behavioral portion of an Amazon final-round interview (Software Development Engineer internship). Prepare strong, structured r...
Compute Minimum Production Days
Question You are given a list of product IDs products, where products[i] is the type of the product that must be produced at step i, and a non-negativ...
Write SQL revenue and anomaly queries
You are given two tables. Table: transactions | Column | Type | Description | |---|---|---| | transaction_id | int | Unique identifier for each transa...
Write SQL Data Transformation Queries
Use SQL to solve the following data transformation tasks. Assume standard SQL features are available, including window functions and recursive common ...
Write SQL to analyze CA residency history
You have two SQL tables. Table 1: user_info (current snapshot) - id (user id) - shard (partition column) - name - country - state - created_date Table...
Solve two string problems
You are asked to solve the following two coding problems. 1. Count unique Morse code translations You are given an array of lowercase English w...
Describe ETL and pipeline challenges
Question You are interviewing for a Data Engineer co-op / intern role at RBC (Royal Bank of Canada). The technical screen is a set of resume-based and...
Implement Portfolio Trading Optimizer
You are given an array prices, where prices[i] is the price of one stock on day i. You may perform multiple buy/sell transactions over the period, but...
Compute Graph Spread and Portfolio Trades
Answer both implementation tasks. Task 1: Maximum connected-component label difference Implement maximumDifference(int gNodes, List<Integer> gFrom, Li...
Encode and Rebuild a Binary Tree
Design two functions for a binary tree: - encode(root) -> string - decode(data) -> root Each tree node contains an integer value and has up to two chi...
Implement two string utility functions
Implement the following Python functions: 1. number_of_character(string, char) - Return the number of times character char appears in string. - ...
Write queries for follows and bookings
You are given tables/logs from a consumer app. Solve the following independent tasks. Part A — Active following as of a date (SQL) You have a follow e...