Redis is a very good distributed caching service you can use to improve your services’ performance. Most important is FAST! Redis is really fast in terms of caching. At my work, running a data centric web services, we use Redis heavily to make sure our users can see and visualize data right away. Our services start with a single Redis instance in Azure. We choose the most expensive plan to achieve the highest network bandwidth and throughput — it’s a 53GB single instance redis cache. As we use this Redis cache more and more widely, we start seeing a simple READ action takes about 200ms to retrieve a JSON of 100KB. Adding a few hundred milliseconds to a AJAX calls on a page may not to be a big deal, but if there are a lot of data calls it starts impacting user experience. In addition, our services could get into a burst situation to request cache that slows down the performance even more. ...

Many of us would like to understand a city through its culture, business, people, and history. But here, I would like see a city that I am living through a new angle by looking at the 911 calls in seattle area. Very fortunately I have a chance to look at the 911 call data (both fire and police department) in the city of Seattle. The data.seattle.gov provides developers and scientists a complete access to their public data source. Among my current explore, I find the 911 call data is a very interesting angle to observe the city. The data I explored is roughly from 2011 till now and it has two parts: fire and police. In each of the data set, they record every event’s reason, time and location point. ...