Fast sorting on flash memory sensor nodes

Abstract

Sensor nodes are being used in numerous domains for data collection and analysis. The ability to perform on device data processing increases the functionality and lifetime of a network as it avoids network transmission. Previous work has developed algorithms for sorting on sensor nodes with flash memory. These algorithms favour reads over writes due to the asymmetric costs. However, previous algorithms have not exploited the ability to perform random reads at the same cost as sequential reads. In this paper, we propose a new algorithm called Flash MinSort that uses random reads to rapidly sort in flash memory using a small amount of memory. The algorithm works especially well for sensor data which is often temporally clustered. Experimental results on random and real sensor data show that Flash MinSort is two to ten times faster than previous approaches for small memory sizes where external merge sort is not executable.