Databricks Interview Questions
Practice 100 real Databricks interview questions for 2026. Covers all top categories — Coding & Algorithms, System Design, Behavioral & Leadership, Statistics & Math, Software Engineering Fundamentals — across Software Engineer, Data Scientist, Machine Learning Engineer, and Data Engineer roles. Real questions from actual interviews with detailed solutions; this collection explains what’s distinctive about Databricks interviews, what interviewers evaluate, what to expect in each round, and how to structure your interview preparation. Expect a heavy software-engineering tilt: Software Engineer rounds repeatedly probe storage and data-platform design (hierarchical file systems, cache designs, lakehouse tradeoffs), distributed job scheduling and dependency-aware pipelines, concurrency and multithreaded systems (synchronous log writers, thread-safe KV stores), and performance-focused algorithmic problems and query optimizations. Data Scientist questions emphasize regression assumptions and coefficient transformations, similarity search across datasets, hypothesis testing and metric tradeoffs (ROC-AUC vs PR-AUC), and product-analytics counting problems. Machine Learning Engineer prompts focus on implementing algorithms (gradient descent, lazy arrays) and safety/OOM detection for models. Data Engineer coverage targets data-quality diagnostics, Spark/partitioning and pipeline performance. To prepare, prioritize timed coding practice, system-design sketches that show tradeoffs for data systems, concise statistics explanations, and polished STAR stories for behavioral rounds.
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Implement run-length encoding and decoding
You are given a string consisting of lowercase English letters. You need to implement run-length encoding (RLE) and its corresponding decoding. 1. Enc...
Evaluate ACL rules for IP and CIDR
Problem You are implementing an IPv4 access-control list (ACL). The ACL contains ordered rules; each rule has: - action: either ALLOW or DENY - cidr: ...
Answer behavioral screen questions
Answer behavioral screen questions HR Screen — Behavioral Questions (Software Engineer) Context: You are interviewing for a Software Engineer role in ...
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...
Explain Linear Regression Feature Transformation Equivalence
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Implement lazy array and KV store
You are asked two coding problems in the same interview round: 1. Implement a lazy array abstraction - Create a LazyArray<T> that wraps an input li...
Test if coin is fair from 560 tails
You flip a coin n = 1000 times and observe 560 tails. At significance level α = 0.05, test whether the coin is fair. Requirements: - State the null an...
Relate coefficients under linear feature transformation
Suppose you are fitting a linear regression model and you consider two different feature parameterizations. Original features: x1, x2. Transformed fea...
Compute last-5-minute QPS in memory
Problem You are building a lightweight in-memory component that tracks the query load (QPS) of a service. Design a data structure with two operations:...
Design KV store with sliding-window average QPS
Problem Design an in-memory key–value store that supports mutation operations and can report the average QPS (queries per second) over a recent time w...
Design Tic-Tac-Toe and QPS data structures
You are given two independent coding problems that focus on data structure and API design. --- Problem 1: Generalized Tic-Tac-Toe Game with Simple AI ...
Optimize a SQL query plan tree
Problem You are given an in-memory representation of a SQL query plan as a tree of nodes (a relational algebra plan). Each node is one of: - Scan(tabl...
Find shortest path in a Fibonacci-ordered tree
You are given a recursively-defined binary tree T(order) whose shape depends only on order (not on node values). Nodes are labeled 0..N-1 using preord...
Implement a rate-limited hit counter
You are designing a hit counter that records the number of hits received in the past 5 minutes. Implement a class HitCounter with the following method...
Find first CIDR block covering IP
You are given: - A single IPv4 address as a string, e.g. "192.168.1.5". - A list of CIDR blocks (IPv4), each as a string in the form "a.b.c.d/x", wher...
Implement RLE and bit-packing compression
You are asked to implement two related compression/decompression schemes: Run-Length Encoding (RLE) and bit-packing. --- Part 1 — Run-Length Encoding ...
Find Path Between Fibonacci Tree Nodes
You are given a special family of binary trees called Fibonacci trees. Define the tree T(k) recursively: - T(1) is a single node. - T(2) is a single n...
Find Fastest Commute Mode
You are given a 2D city grid containing: - S: starting location - D: destination - X: blocked cell that cannot be entered - 1, 2, 3, 4: cells usable b...
Check if CIDR is fully canceled by rules
You are given: - A target CIDR block T as a string, e.g. "10.0.0.0/16". - A list of rule CIDR blocks. Each rule has: - A type: either "allow" or "de...
Diagnose and fix multicollinearity in income regression
You want to estimate the relationship between gender and income using a regression model, while controlling for other covariates such as: - age - educ...