Data Engineer Interview Questions
Practice 160 real Data Engineer interview questions for 2026. Covers companies like Meta, TikTok, RBC Royal Bank, and Point72 — real questions from actual interviews with detailed solutions. This collection of Data Engineer interview questions is designed for hands‑on interview preparation: expect live SQL and Python exercises, pipeline design and debugging, and case problems that test data modeling, throughput and latency tradeoffs. What’s distinctive about data engineering interviews is the mix of coding plus systems thinking: interviewers evaluate SQL fluency and data modeling, end‑to‑end pipeline architecture (streaming, Spark, Kafka) and data reliability/observability. Meta, TikTok, RBC Royal Bank, and Point72 are actively hiring for this role and commonly test scalable ETL design, warehouse/schema design and production reliability. To prepare, practice medium‑to‑hard SQL, build a few Spark/streaming exercises, sketch architecture tradeoffs for high‑throughput pipelines, and rehearse concise behavioral stories that show ownership and incident response.
"I got asked a hardcore MCM DP question and I saw it on PracHub as well. Solved that question in 5 minutes. Without PracHub I doubt I could solve it in 5 hours. Though somehow didn't get hired, perhaps I guess I solved it too fast? /s"
"Believe me i'm a student here jn US. Recently interviewed for MSFT. They asked me exact question from PracHub. I saw it the night before and ignored it cause why waste time on random sites. I legit wanna go back and redo this whole thing if I had chance. Not saying will work for everyone but there is certainly some merit to that website. And i'm gonna use it in future prep from now on like lc tagged"
"10 years of experience but never worked at a top company. PracHub's senior-level questions helped me break into FAANG at 35. Age is just a number."
"I was skeptical about the 'real questions' claim, so I put it to the test. I searched for the exact question I got grilled on at my last Meta onsite... and it was right there. Word for word."
"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."
"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."
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"Legit the only resource you need. TC went from 180k -> 350k. Just memorize the top 50 for your target company and you're golden."
"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."
"Literally just signed a $600k offer. I only had 2 weeks to prep, so I focused entirely on the company-tagged lists here. If you're targeting L5+, don't overthink it."
"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."
Aggregate user logs into 30-minute sessions
You are given a CSV file with columns: user_id | log_datetime | topic Example input rows (already in time order for the same user): - 001 | 2025-03-01...
Generate All Well-Formed Parenthesis Strings
A string of parentheses is called well-formed if every opening bracket ( has a matching closing bracket ) and the brackets are correctly nested. For e...
Explain Pandas and SQL Basics
You are interviewing for a Data Engineer internship. Answer the following short data-manipulation questions: 1. In pandas, what is the difference betw...
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...
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 SQL for session analytics
This question evaluates SQL proficiency and data engineering competencies, including deduplication, joins, time-series aggregation, rolling-window cal...
Compute shipping cost with tiered pricing
This question evaluates the ability to implement tiered billing and aggregate shipping costs across order line items, testing competencies in algorith...
Explain pandas and SQL basics
You are interviewing for a Data Engineer co-op/intern role. Answer the following short technical questions. Python / pandas: 1. What is the difference...
Maximize watch time under adjacency constraint
You are given a sequence of videos in a feed. - Input: - An integer array duration[1..n], where duration[i] is the length of video i in seconds. -...
Compute Max Score From Up to 3 Categories
You are implementing a scoring function for a library summer reading program. Each book a student read is represented as a tuple (category: str, point...
Implement a Weighted Eviction Cache
This question evaluates proficiency with data structures and algorithmic design for resource-constrained caching, specifically weight-aware eviction p...
Implement most_frequent_key without using max()
Problem (Python OOP) You are given two classes. Parent precomputes frequency counts of items (as strings) from an input list. `python class Parent: ...
Count islands using BFS without modifying grid
You are given an m x n binary grid grid where: - 1 represents land - 0 represents water - Islands are groups of horizontally or vertically adjacent la...
Define success metrics for a social feed
Define Success Metrics for a Social Feed Feature You are evaluating a change to the main social feed in a large-scale consumer app. Assume events are ...
Debug a Hive Query for DAU
You are given two Hive tables: users(user_id BIGINT, created_at TIMESTAMP) and events(user_id BIGINT, event_time TIMESTAMP, event_name STRING) PARTITI...
Solve Python and SQL data tasks
Complete both tasks: 1) Python: Implement a function flatten(nested) that takes a list whose elements are integers or arbitrarily nested lists of inte...
Find top 3 books by total borrowed time
Using copies(copy_id, book_id) and checkouts(copy_id, checkout_date, return_date), compute for each book_id the total borrowed duration as the sum ove...
Optimize SQL to minimize scans
Given a large analytics query, refactor it to minimize table scans. 1) Replace unnecessary CTEs that cause multiple scans with inline aggregations or ...
Solve library SQL and Python tasks
You are given a library domain. Assume these tables: - books(book_id, author_id, title) - authors(author_id, name) - copies(copy_id, book_id, conditio...
Implement classes within an abstract Python framework
You are given an existing Python codebase (~200 lines shown) that defines an abstract base class DataProcessor with abstract methods load(self), trans...