36 responses to “Quora’s Technology Examined”

  1. Ellie Kesselman

    Very interesting! I knew that Quora was SQL, much to the disdain and surprise of the NoSQL types.

    However, as a user, I’d noticed that Quora’s platform seemed to be able to withstand as much abuse as I could throw at it through my undisciplined work and browsing habits. High reliability, fast, not a Chrome browser resource hog, real-time updating of information without locking out users, yet no getting hung. I’ve never timed out on Quora, either.

    Of course (unless one is Robert Scoble, snark snark), there aren’t many image files to contend with, nor multi-media, which are resource hogs.

    Thank you so much for this post, and for satisfying some of my curiosity. (I need to go back and re-read it carefully, there’s a lot of content here).

    I look forward to more!

  2. Amul

    Really impressive breakdown of their stack.. I thought it was php driven considering the Facebook legacy. I hope they open source their search..

  3. Alex Toulemonde

    Thanks Phil for this comment. I finally went back to it and break it down. This is brilliant and inspiring.

    I believe we’re missing something crucial: stats. Scaling up is getting easier but setting up this kind of architecture requires a lot of learning and time. So the question for us, entrepreneurs, would be WHEN since you answered to the HOW.

    At how many HTTP or SQL requests per day should we start caring about details. Except the fact that NoSQL does not appear necessary before 1M users, what other milestones should we watch out to know when IT’S TIME.

    See U soon.

  4. Jonathan

    i have to think this would be incredibly helpful to anybody committing to a web-based project in the future. thanks a bunch!

  5. Jürgen Messing

    I must smile a little about the surprised reactions on the scale-at-the-application thing. This is so commonly used in the industry long before shared caches came around. In Telecoms billing software for example, especially software that makes the weird real-time calculation for prepaid subscribers, you often can see them scale the load by the subscribers’ MSISDN. This does not actually distribute the load perfectly balanced, but it’s simple to implement. Each node could have its own database locally, even MySQL. Batch processes running during the less active hours of the service redistribute subscriber data if needed.

  6. Jon Forrest

    Very interesting. This is how the big boys/girls do it.

  7. tarnowski.krzysztof

    Excellent post. Thanks Phil!

  8. Horia Dragomir

    I must admit I too stopped to ponder why Quora was not using a nosql database — but then I thought “Hey, whatever flies your kite.”

    Also, thank you for the further reading suggestions!

  9. Sabya

    Quora uses persistent connections. A HTTP connection is established with the server when you start typing the search query. This connection is kept open and further requests are made on this same open connection. The connection will terminate (times-out) if not used for 60 seconds. If a connection times-out then a new connection is established when typing begins.

    By “persistent connections”, do you mean HTTP keep-alive (http://en.wikipedia.org/wiki/Keepalive)?

  10. magicshui

    Thanks for your post, especially the long polling,useful for me~

  11. Nitesh Thakur


  12. Richard Weisberger

    Great Piece.

    Do you have a sense for how many man hours this would take to build?

  13. Quora

    What are the good resources to learn about distributed, scalable, robust software architecture/infrastructure building?…

    You can add Phil Whelan’s article on Quora’s architecture too: http://www.bigfastblog.com/quoras-technology-examined...

  14. Quora : le test | docnews

    [...] Notons d’abord, qu’en déhors de ses défauts, Quora a d’extraordinaires qualités, parmi lesquelles une fluidité à toute épreuve. Tout est facile à faire : poser une question, la commenter, la modifier, la retrouver, y répondre, suivre des gens, ne plus les suivre, suivre une question, une thématique. Toutes les fonctionnalités et les choix techniques de Quora sont détaillés ici. [...]

  15. Quora

    Does Quora use an evented server? And if so which one?…

    They use Tornado, and a framework called LiveNode. http://www.bigfastblog.com/quoras-technology-examined provides an excellent, recent summary gleaned from the founders’ answers on this site….

  16. Quora 用了哪些技术 ? - webguo在路上

    [...] by Fenng@dbanotes.net很多团队都在学习、研究 Quora 。前段时间看到这篇 Quora's Technology Examined ,阐述了 Quora [...]

  17. XU Qiang

    very nice post. it is really helpful. thanks a lot!

  18. Naoya Makino (via Quora)
  19. taolinke

    Thank you so much for this post and it’s very impressive.
    It let me know a lot.
    Just like you said,”Quora is a great example of a modern tech start-up.”

  20. Tutte le tecnologie che fanno funzionare Quora | Edit - Il blog di HTML.it

    [...] Interessante post questo sul blog di Phil Whelan, che esamina Quora e le tecnologie che ne permettono il funzionamento, quasi tutte (se non tutte) Open Source. [...]

  21. BrandSocialism – 33 Quora Q&A Resources: get actual ROI out of using it

    [...] Quora’s Technology Examined | Phil Whelan’s Blog [...]

  22. Ramesh

    It is a great post and very insightful. Thank you.

  23. Quora

    What are the programming languages and frameworks the top NYC startups are using?…

    Twitter: Main application is made on RoR. Using, Scala for insights and data mining at the back end. Facebook:is having a hard time because it was initially made on PHP. FB chat + All newer features post 2006 are based on frameworks in Erlang, Haskell,…

  24. Quora

    What’s the architecture of Quora like?…

    Good summary here by Phil Whelan: http://www.bigfastblog.com/quoras-technology-examined...

  25. David Crow | Under the Hood | Chango | StartupNorth

    [...] I am always curious at what startups are using for the technology under the hood [...]

  26. Quora

    Can I build site like Quora on wordpress framework?…

    You could build a site like Quora (Questions & Answers) but not exactly like Quora. Quora uses some open source but also in-house developed technologies and you or who is developing your site using WordPress will need to replicate, not an easy task (es…

  27. The Significance of Quora’s LiveNode Technology « semil's blog

    [...] Two: Quora’s own internal development of frameworks, specifically LiveNode (LN) and WebNode2 (WN2), put this company in another class of technology endeavors. Earlier in 2011, Phil Whelan wrote a very thorough assessment of Quora’s technology stack — it’s a must read and touches on LN and WN2, too. (I’d highly recommend this piece, click here.) [...]

  28. Quora

    How is Quora planning to get further traction?…

    I have been thinking about Quora recently and it’s current traction. I like Quora a lot and think that it’s one of the smartest companies out there but here’s the thing. What is happening with it’s traction? There is no doubt that it is cutting edg…

  29. Quora

    What front-end & back-end technologies does Quora use?…

    The answer to this question is in this blog url: http://www.bigfastblog.com/quoras-technology-examined...

  30. Quora

    Is Quora a digital media company, a technology company, or both?…

    My take is a bit different. I would say that Quora is, at this time, more of a technology company and less than a media one. Why? Because they have built among the first real time Q&A websites (as far as I know none of the rivals has something like thi…

  31. Quora’s Technology Examined « ABENDance

    interesting article

  32. Quora

    Why does Quora use so much RAM?…

    Well, if we look in the source code we see that almost the whole this page is generated using Javascript. Now, I am not a front end developer but I do know that Javascript is not easy on the processor and RAM (try opening this page for example What sta…

  33. Tommy
  34. krishnas

    Great article. One question I got is why HAProxy is used instead of AWS autoscalaing. Any thoughts?