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Databricks Interview Questions

Reconstructed from 377 verified candidate reports across 34 questions. Jan 2025 – Oct 2026.

This page is a live view of every Databricks interview question AceOffer has indexed — pulled from candidate reports, not invented from job descriptions or one founder’s memory. Every question shows how many times it’s been reported and when it was last seen. The catalog gets a refresh pass every month.

AceOffer is not affiliated with, endorsed by, or sponsored by Databricks. Questions are reconstructed from interview experiences candidates shared, not from Databricks materials.

377
candidate reports
34
distinct questions
5
round types
Monthly
refresh cadence

Key facts

  • •34 distinct Databricks interview questions indexed
  • •377 candidate reports across the catalog
  • •Most reported: KV Store QPS / Hit Counter (Map Operations) — 38× (last seen September 2026)
  • •Round mix across candidate reports: coding 55%, system design 16%, phone screen 11%, behavioral 11%, technical deep-dive 6%
  • •Most common coding topics: stateful class design (3 questions), iterators and generators (2 questions), simulation and game rules (2 questions)
  • •16 of the 34 questions were last reported in Aug–Oct 2026
  • •Reports span Jan 2025 – Oct 2026
  • •Refreshed monthly · last updated October 2026

Browse Databricks interviews by topic

Coding Interview QuestionsSystem Design Interview QuestionsBehavioral Interview QuestionsMachine Learning Interview QuestionsInterview Process & Rounds

The Databricks loop, from candidate reports

Databricks' loop is a recruiter call, one technical phone screen, and a virtual onsite of two coding rounds, a system design round, and a behavioral or hiring-manager round. Staff-level loops can add a tech-fit project discussion, and one senior recruiter's list adds an architecture round. Then comes the part the reports talk about most: a hiring committee and reference checks after the onsite. Several candidates report strong-hire feedback on every round followed by a committee rejection with no technical reason given, and reference strength — including whether a current manager can be reached — is named as the deciding factor more than once. The coding rounds run 45-60 minutes, and implementation-style rather than LeetCode: firewall rules over CIDR blocks, a key-value store that reports its own QPS, a snapshot-set iterator, a multi-threaded log writer with synchronous disk writes. The pool is small enough that candidates report getting a question they had already prepared for, and the grading is strict about it: one candidate passed every phone-screen test case with a single small bug and was rejected the same day. Interviewers expect you to write your own tests. In system design the interviewer usually has a standard answer in mind and steers toward it; reports advise following that lead rather than arguing, and pseudocode is expected for the concurrency parts. Onsite results usually arrive within about a week; candidates who go on to references wait one to three weeks more, and a one-year re-apply freeze is reported.

What does Databricks ask in each interview round?

Databricks interviews span 5 distinct round types, broken down below. Counts reflect distinct questions per round, not number of times asked. Frequencies on individual question cards show how many candidates reported getting that specific question.

Usually two 45-60 minute rounds, implementation-style rather than LeetCode: CIDR firewall matching, a KV store that tracks its own QPS, the snapshot-set iterator, and a multi-threaded log writer with synchronous disk writes.
13 questions

Most-reported: KV Store QPS / Hit Counter (Map Operations) (38 reports)
One round, with pseudocode expected for the concurrency parts: the bookstore broker with async fan-out, an in-memory KV cache with a write-ahead log, Slack-style messaging, and a strongly consistent file system.
9 questions

Most-reported: Bookstore / Book Seller Platform System Design (23 reports)
Durable event writers and persistent KV stores drilled at the systems-programming level, plus ML theory and model-integrity questions on MLE loops.
5 questions

Most-reported: Durable / Persistent KV Store (12 reports)
One coding screen. The multi-mode commute shortest-path problem is one of the most reported, with a recorded trap: one BFS per transport mode is rejected in favour of a single pass.
4 questions

Most-reported: Optimal Commute / Shortest Path with Multiple Transport Modes (30 reports)
A BQ round and a cross-functional hiring-manager round, both weighed fully by the committee; one report failed on the HM round alone.
3 questions

Most-reported: Behavioral Questions (Databricks BQ Round) (27 reports)

Which Databricks interview questions come up most?

These are the Databricks questions reported most across the loops we’ve indexed, sorted by candidate-report frequency.

QuestionRoundReportedLast seen
KV Store QPS / Hit Counter (Map Operations)Coding38×September 2026
IP CIDR Firewall Rules MatchingCoding34×August 2026
Optimal Commute / Shortest Path with Multiple Transport ModesPhone Screen30×August 2026
Behavioral Questions (Databricks BQ Round)Behavioral27×July 2026
Bookstore / Book Seller Platform System DesignSystem Design23×October 2026
Concurrent Log Writer (Durable Event / Data Writer)Coding22×August 2026
Run-Length Encoding (RLE) / Bit-PackingCoding18×August 2026
Tic-Tac-ToeCoding18×September 2026
Snapshot Set / Iterator DesignCoding17×July 2026
Fibonacci Tree / Path FindingCoding17×July 2026

The full index is below, or browse the Databricks catalog →

Every Databricks interview question we’ve indexed

All 34, grouped by round and sorted by how often candidates reported them. Each links to the question, its reported follow-up count, and when it was last seen.

Coding (13)

System Design (9)

Tech Deep Dive (5)

Phone Screen (4)

Behavioral (3)

Read two Databricks questions free

Full problem statements, candidate-reported follow-ups, and walkthroughs. No signup needed.

Free previewCoding33× reported
IP / CIDR Firewall Rules Matching

Given firewall rules as CIDR blocks with allow or deny actions, return the verdict for an IP: the first rule it falls within wins. Reports agree on the follow-up — the query becomes a CIDR block itself, allowed only if every address in it is covered by allow rules — and on the ladder after it: write your own test cases, pseudocode the CIDR-versus-CIDR overlap check, then scale to firewall-log volumes. One candidate's recruiter debrief named the weak spot exactly: building the bit mask for the prefix length. This is the free preview — full statement, follow-ups, and a solution run against its test cases.

Last reported August 2026Read it →
Free previewSystem Design22× reported
Bookstore Broker Platform

You are the middleman: a customer submits an ISBN, a bid price, and a payment method; your system fans out to hundreds of partner bookstores, buys automatically if the lowest price beats the bid, and otherwise returns the best price found. The interviewer hints are consistent across reports — the downstream calls are async and the point is not overloading the sellers, you design the seller API yourself, and when you reach for a lock the interviewer asks whether you could just return a payment failure instead. The recorded failures are the sold-out-between-quote-and-hold race, and spending the hour on clarification without ever reaching a schema.

Last reported August 2026Read it →
Free previewCoding16× reported
Concurrent Log Writer

Implement a logger shared by many threads where a write must not return until the record is on disk, then raise throughput without giving up that guarantee — batching writers behind one fsync while each caller still blocks for its own record. Reports say the interviewer has a specific implementation in mind, so clarify preferences before coding. One debrief was blunt: do not reach for thread-safe containers, show that you know when to lock and unlock; another candidate was graded on whether busy-waiting had actually been eliminated. Know your condition variables.

Last reported August 2026Read it →
What passing candidates do
  • •Clarifying requirements exhaustively before writing a line. On the log writer the interviewer had a specific implementation in mind, and the report that passed says the round turned on pinning down preferences upfront; another advises recognising early when the interviewer has a direction and aligning with it.
  • •Writing your own test cases and running them before the interviewer asks. Two debriefs cite test coverage directly — one rejection read ‘test cases not comprehensive’ — and a tic-tac-toe candidate lost time because the function never specified move order and the tests had to establish it.
  • •Showing the concurrency primitives rather than hiding behind a thread-safe container. One candidate who had just taken the round advised against thread-safe data structures: demonstrate when to lock and unlock. The Slack design round asks the same thing in reverse — ‘why not a plain HashMap, and how does ConcurrentHashMap work inside?’
  • •Raising the failure mode before the interviewer does. The bookstore round's recorded pass is the candidate who volunteered that the cheapest copy might be sold between the quote and the hold, and that the downstream sellers must not be overloaded; the KV-cache round rewards addressing WAL truncation and snapshot coordination unprompted.
  • •Following the interviewer's lead in design. Reports describe interviewers who guide toward the answer they want and probe every decision; the advice is to listen and adapt rather than defend, and to explain each choice out loud because nothing is assumed understood.
Where candidates lose points
  • •Shipping code with a bug. One candidate passed all test cases with one small bug and received a same-day rejection; another wrote a working solution slowly with bugs and got no follow-up questions, which the report reads as the interviewer having already decided.
  • •Running out of time on the second problem or the optimal version. A redo round failed on not reaching the O(n) solution with code incomplete; a bit-manipulation second problem sank another loop; and on the commute problem the interviewer rejected a min-heap solution and one BFS per transport mode, insisting on a single pass.
  • •Using a thread-safe structure you cannot explain. Reaching for ConcurrentHashMap without knowing its internals is a recorded failure in the multi-threaded Slack variant, and the log writer is graded on whether busy-waiting was actually eliminated.
  • •Walking into the distributed file system round on intuition. One rejection says it plainly — ‘talked entirely from gut feeling, so I failed’ — and the file system round explicitly rejects S3-style last-writer-wins copied from a textbook when the requirement is strong consistency.
  • •Treating the behavioral and hiring-manager rounds as a formality. One loop had strong hire on all three technical rounds and failed on a very negative HM round; staff candidates were dinged for examples whose scope was too small for the level.

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