The document discusses scaling event analytics applications using Ruby on Rails and MongoDB. It describes how the author's startup initially used a standard Rails architecture with MySQL, but ran into performance bottlenecks. It then explores solutions like replication, sharding, key-value stores and Hadoop, but notes the development challenges with each approach. The document concludes that using
![Scalable Event Analytics with MongoDB & Ruby on Rails](https://cdn-ak-scissors.b.st-hatena.com/image/square/4727992ea6df0d40a2f6d58a3bf4da80db59b9dd/height=288;version=1;width=512/https%3A%2F%2Fcdn.slidesharecdn.com%2Fss_thumbnails%2Frubyconfchina-2010-slideshare-100628215030-phpapp01-thumbnail.jpg%3Fwidth%3D640%26height%3D640%26fit%3Dbounds)