Nowadays, in-memory column store database systems are state-of-the-art for analytical workloads. In these column stores, a full column scan is a fundamental key operation and thus, the optimization of this primitive is very crucial from a performance perspective. For this optimization, advances in hardware are always an interesting opportunity, but represent also a major challenge. At the moment, hardware systems are more and more changing from homogeneous CPU systems towards hybrid systems with different computing units. Based on that, we focus on column scan acceleration for hybrid hardware systems incorporating a Field Programmable Gate Array (FPGA) and a CPU into a single system in this paper. The advantage of those hybrid systems is that the FPGA has usually direct access to the main memory of the CPU avoiding data copy which is a necessary procedure in other hybrid systems like CPU-GPU architectures. Thus, we present several FPGA designs for a recent column scan technique to fully offload the scan operation to the FPGA. In detail, we present our basic FPGA design and different optimization techniques. Then, we present selective results of our exhaustive evaluation showing the benefit of our FPGA acceleration. As we are going to show, we achieve a maximum speedup of factor 7 compared to a single-threaded CPU scan execution.
Lisa, N.J., Ungethüm, A., Habich, D., Lehner, W., Nguyen, T.D., & Kumar, A. (2018). Column Scan Acceleration in Hybrid CPU-FPGA Systems. ADMS@VLDB.