Data Engineer Interview Questions
Practice 134 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."
Build a One-Pass Data Cleaning Pipeline
You are given one or more large Parquet files containing millions of publicly available, web-scraped documents. The documents will later be tokenized ...
Build a Transaction CSV Cleaning Pipeline
You receive a raw CSV file containing customer transaction data with the columns date, amount, customer_id, payment_method, and notes. The file has se...
Design a Conversation Log Ingestion Pipeline
Design a daily data pipeline for analytics over conversation logs. Every day, a JSONL file lands in object storage. The file is associated with a load...
Write February Resource Usage Query
You are given two database tables that record per-application resource usage: - cpu_metrics(application_id, dt, usage_percentage) - memory_metrics(app...
Explain Spark Execution and Optimization
You are interviewing for a Data Engineer role. In a 30-minute discussion on production data engineering, the interviewer probes how well you understan...
Implement Game Metadata Lookups
You are given a list of game metadata records. Build an in-memory representation that can store each game's name, release date, platforms, genre, publ...
Design an event analytics platform
Design a data platform for raw product events with this schema: - event_id - event_type - user_id - user_setting as a nested object - event_metadata a...
Design Video Call Analytics Tables
You are building analytics tables for Discord video calls. Video-call activity is recorded from both client-side and server-side logs. Design a data m...
Write SQL for first share and closest collaborator
You are given event data about users viewing design files. Assume the following tables: - files(file_id, creator_id) - creator_id is a VARCHAR user ...
Design Transaction Data Quality Checks
You own data quality for the same credit-card transaction dataset. transactions | column | type | description | |---|---|---| | transaction_id | integ...
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 ...
Explain seasons and compound interest
Answer the following basic reasoning questions: 1. Why is summer generally hotter than winter? 2. Suppose you invest $1,000 at a 100% annual interest ...
Evaluate credit-limit increase profitability
Business/Analytics Case: Credit Limit Increase Strategy You are a data scientist supporting a consumer credit business. Scenario The company is consid...
Validate an IPv4 address string
Given a string s, determine whether it is a valid IPv4 address. A valid IPv4 address: - Has exactly 4 parts separated by dots (.): x1.x2.x3.x4 - Each ...
Write SQL using joins and window functions
SQL Coding: Rank within Groups with Joins You are given two tables: accounts - account_id (string) - customer_id (string) - segment (string) — e.g., "...
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...
Build a Least-Recently-Used Store
Implement an in-memory key-value store with least-recently-used eviction. The store is initialized with a positive integer capacity and supports two o...
Solve SQL and PySpark Data Tasks
Complete the following two data engineering coding tasks. Part A: Detect repeated crypto-transfer patterns in PostgreSQL You are given a PostgreSQL ta...
Design Data Quality and Observability Pipeline
Design a production data orchestration, data quality, and observability framework for batch and streaming data pipelines. Your design should address: ...
Write SQL revenue and anomaly queries
You are given two tables. Table: transactions | Column | Type | Description | |---|---|---| | transaction_id | int | Unique identifier for each transa...