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.
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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...
Define metrics and data model for product features
This question evaluates a candidate's product sense and data engineering competency, including defining core success metrics, designing dashboard visu...
Write SQL and merge linked lists
The technical interview included two coding-style tasks: a SQL analytics query and merging two sorted linked lists. Constraints & Assumptions - For SQ...
Model entities for feed content and shares
Scenario You are designing the data model for a social app’s News Feed that shows multiple content types (text, image, short video). Users can interac...
Tackle Python tasks under time pressure
In a 15-minute coding round, implement a small Python function or class to solve a well-scoped problem within about 5 minutes of coding. 1) State 1–2 ...
Implement RotatingFileSink in hierarchy
You are given an existing Python 3.10 codebase with an abstract base class RecordSink (from abc import ABC, abstractmethod) that defines open() -> Non...
Design TikTok Data Engineering Systems
This question evaluates data engineering competencies including scalable streaming ingestion, processing orchestration, data partitioning and failure ...
Write Transaction Analytics SQL Queries
You are given a credit-card transaction dataset with the following tables. transactions | column | type | description | |---|---|---| | transaction_id...
Compare Data Infrastructure Storage Choices
You are designing data infrastructure for an autonomous-driving company. Discuss the following storage and processing concepts and trade-offs: 1. In P...
Design config rollout and click aggregation
This question evaluates system design and data engineering competencies, focusing on distributed systems, global configuration management, deployment ...
Explain concurrency and reliability tradeoffs
This question evaluates skills in concurrent programming (thread-safety, synchronization primitives, memory visibility and lazy initialization) and di...
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...
Find Every Project with the Most Employees
The interview report explicitly identified the “Project with Most Employees” SQL exercise. Use the following self-contained PostgreSQL schema: `text e...
Find the Highest-Paid Employee in Each Department
The interview report explicitly identified the “Department Highest Salary” SQL exercise. Use the following self-contained PostgreSQL schema: `text dep...
Diagnose data quality and pipeline performance issues
Diagnose data quality and pipeline performance issues Scenario You are interviewing for a Data Solutions Architect role. A customer is using a cloud d...
Evaluate impact of short videos in feed
Scenario You work on a social app’s main News Feed. The team wants to introduce a short-form video module ("Reels") into the feed. Prompt 1. How would...
Write SQL Data Transformation Queries
This question evaluates proficiency in SQL data transformation and aggregation, testing competencies such as monthly-reset running totals, hierarchica...
Solve Two String Problems
You are asked to solve the following two coding problems: 1. Unique Morse Code Transformations You are given an array of lowercase English words, word...
Hiring-Manager Round: Project Ownership, Influence, Communication, and Setbacks
This is the hiring-manager video round for a data/software engineering role. The interviewer opens by asking you to walk through a recent project you ...
Define and analyze product metrics
Product Analytics Case: Short‑Form Video Feed Context: You are evaluating a short‑form video feed feature inside a large social app where users swipe ...