On the Performance of Database Query Processing Algorithms on Flash Solid State Disks

Flash Solid State Disks induce a drastic change in storage technology that impacts database systems. Flash memories exhibit low latency (especially for small block sizes), very high random read and low random write throughput, and significant asymmetry between the read and write performance. These properties influence the performance of database join algorithms and ultimately the cost assumptions in the query optimizer. In this paper we examine the performance of different join algorithms available in Postgre SQL on SSD and magnetic drives. We observe that (a) point queries exhibit the best performance improvement of up to fifty times, (b) range queries benefit less from the properties of SSDs, (c) join algorithms behave differently depending on how well they match the properties of solid state disks or magnetic drives.