Let's discuss system design questions you have encountered in interviews.

Indeed / Eng imgod
Feb 6 28 Comments

There's not a lot of questions online unlike coding questions. Let us know the questions you have come across in interviews (feel free to not reveal the company name, mostly interested in questions)

I've heard of these 2 recently:
1) Design a metrics collector and graphing system. An app uses your client api to count metrics and users can graph data over different time ranges. Asked at LinkedIn.
2) Design Twitter like system and news feed. Quite popular one.

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TOP 28 Comments
  • Amazon seoy
    As an interviewer I have asked questions like these and I have found them to be not very useful to indicate real life performance of candidate.

    I instead ask the candidate to describe the most complex design they have built and ask them to improve them even further or change the constraints on those problems and make it more interesting. This has several benefits:

    1. They doesn’t need new context
    2. It is more grounded in practical experience
    3. It mimics real situations. Rarely are they going to be building something from the ground up. But if that’s the job you are hiring for, they better have designed something from the ground up earlier in which case the strategies continues to apply.
    4. It’s mimics a real life conversation that I would have with them if they were to join. They are much more at ease.
    5. Often they don’t realize they are being interviewed and they let their guards down which also helps me perform a true analysis of candidate
    Feb 6 3
    • MathWorks £€€¥
      What happens if they don't have system design exp? Do you ask for OOP instead?
      Feb 6
    • Verizon hudF20
      I’d also like to hear a response to this
      Feb 6
    • Amazon seoy
      In that case I level them same as new grad. Even new grads have done academic projects where they have designed something ... like a website that they launched on aws ... I can ask what the data model was, drawbacks, how they might scale it if their app became successful, what they can improve, how they tested it, deployed it, monitored etc
      Feb 6
  • Facebook Probe
    Design Blind
    Design Dropbox
    Design Facebook
    Design Gmail
    Design Google Chrome
    Design Google Docs
    Design Google Drive
    Design Google Maps
    Design Google Photos
    Design Google Play
    Design Google Sheets
    Design Indeed
    Design Netflix
    Design Robinhood
    Design Slack
    Design Snap
    Design Splunk
    Design Spotify
    Design Twitter
    Design WhatsApp
    Design Yelp
    Design YouTube
    Feb 6 2
    • Indeed / Eng imgod
      OP
      Would be more interested in questions you have encountered. Are all these you(or someone you know) have been asked?
      Feb 6
    • Facebook Probe
      Definitely.
      Feb 6
  • FactSet / Eng
    Giggsy

    FactSet Eng

    PRE
    Bridgewater Associates
    Giggsymore
    Design a distributed lock service
    Feb 6 5
    • Indeed / Eng imgod
      OP
      Like zookeeper?
      Feb 6
    • Zookeeper is a key value store that happens to provide locks as one of its features.
      Feb 6
    • Indeed / Eng imgod
      OP
      Right, but if I were to use a distributed lock in my app, I'd just use zookeeper. But I guess the interviewer was looking for designing it from scratch.
      Feb 6
    • FactSet / Eng
      Giggsy

      FactSet Eng

      PRE
      Bridgewater Associates
      Giggsymore
      Yeah, it’s more like how would you design just the lock from scratch. How would you go about the fact that multiple processes access it, what if a process dies while it has a lock acquired, etc.
      Feb 6
    • Amazon outoforder
      AnEngineer
      Wrong!

      ZK is a lock service that happens to let you store small volume of key/value data.

      So, it’s basically opposite of what you’re saying. Whenever we’re talking about Key/Value store or you’re asked to design one, you need something like Cassandra/Dynamo for billions or key/vals at very high frequency, redundancy, and scalability. ZK doesn’t have those. ZK’s key/vals are meant to be updated infrequently (for example when a host/service using ZK fails, or leader election needs to happen, and so on).
      Feb 6
  • eBay BGeez
    Design a ticket booking system where one can put a hold on the tkts for 'x' min
    Feb 7 5
    • MathWorks £€€¥
      Whats a good answer to this?
      Feb 7
    • Indeed / Eng imgod
      OP
      You can store tickets on hold in a key value store with x min ttl and check this store before confirming if ticket is available. Lot depends on how are tickets stored currently, volume of such tickets etc.
      Feb 7
    • MathWorks £€€¥
      how would you unreserve the ticket though? seems like key value will take forever
      Feb 7
    • eBay BGeez
      So you would store the to be reserved tkts in KV cache with TTL of x min.
      Couple of cases here:
      1) if reserved you delete the entry in the cache and update the db

      2) user ends sessions delete and unset the reserved flag

      3) some caches like redis have callback when the cache expires you can write a callback to unset the reserved flag
      Feb 7
    • MathWorks £€€¥
      ah okay, i didnt know that there is an automatic way of ttl cache where the system takes care of deletion when time passes. good to know.
      Feb 7
  • New
    champu2

    New

    PRE
    Amazon
    champu2more
    Design twitter notification service.
    Feb 7 0
  • New
    champu2

    New

    PRE
    Amazon
    champu2more
    Design heat map of all uber drivers
    Feb 7 0
  • General Motors / Eng
    RamenCup

    General Motors Eng

    PRE
    Boeing, Lockheed Martin, General Motors
    BIO
    Full stack developer with 6+ years of experience. I enjoy problem-solving, learning, and knowledge sharing.
    RamenCupmore
    Design an e-commerce website.
    Feb 6 0
  • Google chamiyaa
    Design a orchestration service
    Feb 6 0
  • OpenTable Meliodas
    What was the architecture at your last company?

    What did you like and not like about it?

    What would you have done differently?

    How would you scale it to accommodate 10x, 100x, 1000x more users?
    Feb 6 0
  • Microsoft askj123
    Can we also discuss the solutions?
    Feb 6 2
    • Amazon Hoolizon
      Too long for blind
      Feb 6
    • Indeed / Eng imgod
      OP
      Sure, some high level thoughts would be helpful though, depending on the question of course.
      Feb 6
  • Amazon Melgizecci
    design whatsapp
    Feb 6 0