Optimizing Database Operators by Exploiting Internal Parallelism of Solid State Drives

With the development of flash memory technology, flash-based solid state drives (SSDs) are gradually used in more and more devices and applications. In addition to characteristics of flash memory itself, a unique characteristic of SSDs, namely internal parallelism, should also be considered to improve performance of SSDs-based DBMSs, especially query processing. In this paper, we first describe the internal architecture of SSDs and the resulting internal parallelism of SSDs. In the second part, we present a parallel table scan operator, ParaScan, that exploits the internal parallelism of SSDs. Based on ParaScan, we then propose a parallel hash join operator, ParaHashJoin, and a parallel aggregation model, ParaAggr. Experimental results show that ParaScan, ParaHashJoin and ParaAggr on SSDs significantly outperform traditional table scan, hash join and aggregation. Furthermore, sort, as an important basic operator for other complex operators, can also be redesigned based on ParaScan. We design a parallel sort algorithm, ParaSort and then present a parallel ParaSort operator in the third part. Looking forward, database query processing by exploiting internal parallelism of SSDs, can be generalized to other kinds of SSDs with similar internal parallel characteristics.