Using Data Compression for Increasing Efficiency of Data Transfer Between Main Memory and Intel Xeon Phi Coprocessor or NVidia GPU in Parallel DBMS

The need to transfer data through PCI Express bus is considered as one of main bottlenecks in programming for manycore coprocessors and GPUs. This paper focuses on using data compression methods, such as RLE, Null Suppression, LZSS and combination of RLE and Null Suppression to increase efficiency of data transfer between main memory and coprocessor. Chosen compression methods were implemented for two hardware platforms: Intel Xeon Phi coprocessors and NVidia GPUs. A number of experiments were made using these implementations. It is shown that chosen compression methods can be used to increase the efficiency of database processing using Intel Xeon Phi and NVidia GPUs by reducing the time, needed for transferring data on coprocessor, if data satisfies certain conditions. It is also shown that, when a compression method allows one to process data without decompression, such a processing procedure can additionally increase the efficiency of this method.