GPU-PLWAH: GPU-based implementation of the PLWAH algorithm for compressing bitmaps

Bitmap indexes are data structures applied to index- ing attributes in databases and data warehouses. A drawback of a bitmap index is that its size increases when the domain of an indexed attribute increases. As a consequence, for wide domains, the size of a bitmap index is too large to be efficiently processed. Hence, various techniques of compressing bitmap indexes have been proposed. A compression technique incurs some system overhead (mainly CPU) for compression and decompression operations. For this reason, we propose to use additional processing power of graphical processing units (GPUs). In this paper, we present the GPU-PLWAH algorithm that is a parallel implementation of the recently developed PLWAH compression algorithm. GPU-PLWAH was experimentally compared to its traditional CPU version as well as to our previously developed parallel GPU implementation of the WAH compression algorithm. The experiments show that applying GPUs significantly reduces compression/decompression time