High performance stream queries in scala

Traffic monitoring is an important stream processing application, which is highly dynamic and requires aggregation of spatially collocated data. Inspired by this, the DEBS 2015 Grand Challenge uses publicly available taxi transportation information to compute online the most frequent routes and most profitable areas. We describe our solution to the DEBS 2015 Grand Challenge, which can process events at a 10 ms latency and at a throughput of 114,000 events per second.