Standard Deviations on Cassandra – Rolling Your Own Aggregate Function
If you’ve been following the StreamSets blog over the past few weeks, you’ll know that I’ve been building an Internet of Things testbed on the Raspberry Pi. First, I got StreamSets Data Collector (SDC) running on the Pi, ingesting sensor data and sending it to Apache Cassandra, and then I wrote a Python app to display SDC metrics on the PiTFT screen. In this blog entry I’ll take the next step, querying Cassandra for statistics on my sensor data.