Pipelined hash-join on multithreaded architectures

Multi-core and multithreaded processors present both opportunities and challenges in the design of database query processing algorithms. Previous work has shown the potential for performance gains, but also that, in adverse circumstances, multithreading can actually reduce performance. This paper examines the performance of a pipeline of hash-join operations when executing on multithreaded and multicore processors. We examine the optimal number of threads to execute and the partitioning of the workload across those threads. We then describe a buffer-management scheme that minimizes cache conflicts among the threads. Additionally we compare the performance of full materialization of the output at each stage in the pipeline versus passing pointers between stages.