Redis in Action

Foreword

Redis was created about three years ago for practical reasons: basically, I was trying to do the impossible with an on-disk SQL database. I was handling a large write-heavy load with the only hardware I was able to afford—a little virtualized instance.

My problem was conceptually simple: my server was receiving a stream of page views from multiple websites using a small JavaScript tracker. I needed to store the latest n page views for every site and show them in real time to users connected to a web interface, while maintaining a small history.

With a peak load of a few thousand page views per second, whatever my database schema was, and whatever trade-offs I was willing to pick, there was no way for my SQL store to handle the load ...