Solve with Friends

Look at the massive systems you use every day developed by the companies you are interviewing for. What systems did these companies have to design? Create a list of the fundamental system design questions that bubble up in your brain. Here are a few to get you started:

• Twitter: real time feed of the tweets by the people you’re following
• Google: instantly returning the pages matching any search query (Search); Storing and serving massive amounts of video data (YouTube); Aggregating the world’s news by topic (Google news)
• Facebook: serving massive amounts of photos

Start by compiling a list of 10 to 20 of these questions. Then, pick one and try to come up with an efficient design. Make sure you follow the process discussed in the previous sections.

Once you’re ready, find a knowledgeable friend or coworker, go to a meeting room and start discussing ideas. It’d be tons of fun and you’ll learn a lot from the process.

Don’t spend hours: initially, limit your time per question to one hour and ultimately try to fit every question in 20 to 30 minutes.

If you can’t find a friend/coworker, go to a site like HighScalability that contains tons of examples of real-life architectures and compare what you conjured up to what these companies actually did. You’d be surprised how many of the top websites’ architectures are widely available. Keep in mind that these systems were designed by multiple people over multiple months, so don’t expect to be able to come up with every low-level decision they made. Focus on the high-level stuff.