About a month ago, we launched m.yelp.com specifically targeting iPhone, Android, and WebKit-based smart phones. Our engineering team pushes code live on average three times a day. Moving fast means we need to have sound engineering practices internally — such as code reviews by peers and automated testing tools such as unit-tests and static analysis — to catch mistakes before they happen. In this blog post we will detail a misstep that we made and the response that followed. On the morning of October 27, 2011, we were alerted by a team of researchers at Harvard, Yale, and Boston University...

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Summers are tough here at Yelp’s HQ in San Francisco. It’s hard to keep up with all the hot new businesses, order the best food at every restaurant you visit, or even just find that fancy dive bar your friends have been chatting up. If you’re anything like me, you aren’t satisfied just using these features on Yelp - you want to tear them apart, see how they tick, and make them better. The trick? All these features are powered by our incredible review data. The data Yelp is providing the reviews for nearly seven thousand businesses at 30 universities...

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If you read this blog regularly, you’re probably already familiar with Yelp Hackathons. They’re 48 hour periods of time we devote to anyone in the company to crank on projects that they’re excited about. In the past, our Hackathons have included special guests, pinatas and, oh yeah, hacking! This year’s didn’t disappoint, with 28 total projects built, a petting zoo in the office (What? Your company doesn’t have those?) and a High School Science Fair type set-up so our hundreds of Yelp employees in San Francisco could wander, sip some Belgian ale and take a gander at what their fellow...

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Check out the latest post on the main Yelp blog about a day in the life of one of our engineers, JR Heard!

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Yelp converted from using Subversion for source control over to Git over a year ago. As it turns out, however, Git (and distributed version control systems in general) can sometimes be daunting for some developers to understand, especially if they’re used to more traditional centralized versioning solutions. Git can also be a bit daunting for new developers just starting to use source control - it tends to assume that everyone is a power user, offering a high amount of potential, but sometimes at the cost of user-friendliness. In an effort to help more people get a deeper understanding of just...

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When I switched from working on Yelp’s iPhone app to our Android app, one of the first things I encountered was the radical difference between the equivalent classes to handle what I normally consider a “screen” or “page” of an app. On Android, an Activity handles what on iOS you use a UIViewController for, but they work in fundamentally different ways. One of the biggest differences is that on Android you can’t just instantiate a new Activity and display it like you can with a UIViewController. Instead you create an Intent and tell the system to start an Activity based...

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Here in Yelp Engineering, we spend lots of time working on useful and cool stuff for Yelp users of all sorts—consumers, business owners, and even our own Community Managers. Sometimes though, it’s nice to take a break and go hang out with your coworkers for a bit. What better place to “hang out” than a few feet up in the air? Our most recent offsite took us to House of Air, a giant indoor trampoline park. After getting a brief safety introduction from HoA’s “Flight Crew” the team hit the trampolines, and well… I think these say it all: Of...

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At Yelp, we store nearly all of our data in MySQL. At any given time we’re issuing tens of thousands of SQL queries to our database cluster per second, with some individual servers going above the 10k qps mark. Our database cluster consists of billions of rows. In response to a lot of different problems we’ve had to optimize the snot out of our MySQL installation, and we’ve learned some interesting things along the way. A colleague and I recently gave a presentation to some of our coworkers, titled  MySQL Minutiae & InnoDB Internals. The talk covered some good background knowledge that every developer should...

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