If I were to try and tell you exactly what it is about Twitter that makes engineers cry, I'd point out that every single page is dynamic, every user's main page

If I were to try and tell you exactly what it is about Twitter that makes engineers cry, I'd point out that every single page is dynamic, every user's main page requires a giant JOIN, there are lots of writes coming in all the time from every direction and writes are harder to scale, low latency is a requirement for many people, and there's no obvious axis along which to "partition" Twitter. That's more along the lines of what I was looking for. Thanks. This sounds tricky... Just came across this link now: http://highscalability.com/scaling-twitter-making-twitter-10000-percent-faster http://highscalability.com/scaling-twitter-making-twitter-10...