Spatiotemporal Sketch Disaggregation: Streaming Analytics with Heterogeneous Resources

Streaming analytics are essential in a large range of applications, including databases, networking, and machine learning. To optimize performance, practitioners are increasingly offloading such analytics to network nodes such as switches. However, resources such as fast SRAM memory available at switches are limited, not uniform, and may serve other functionalities as well (e.g., firewall). Moreover, resource availability changes over time due to the dynamic demands of in-network applications. In this paper, we propose a new approach to disaggregating data structures, leveraging any residual resources available at network nodes. We focus on sketches, which are fundamental for summarizing data for streaming analytics while providing beneficial space-accuracy tradeoffs. Our idea is to break sketches into multiple 'fragments' that are placed at different network nodes. The fragments cover different time periods and vary in size, and are combined to form a network-wide view of the underlying traffic. We apply our solution to three popular sketches (namely, Count Sketch, Count-Min Sketch, and UnivMon) and demonstrate that we can achieve approximately a 75% memory size reduction for the same error for many queries, or a near order-of-magnitude error reduction if memory is kept unchanged. Further, we demonstrate real-world feasibility through a hardware pipeline for high-speed commodity switches.