Comparison of parallel algorithms for path expression query in object database systems

Proposes a new parallel algorithm for computing path expressions, named the "parallel cascade semi-join" (PCSJ) algorithm. Moreover, a new scheduling strategy called the "right-deep zigzag tree" is designed to further improve the performance of the PCSJ algorithm. The experiments have been implemented in a distributed and parallel NOW (network of workstations) environment. The results show that the PCSJ algorithm outperforms two other parallel algorithms [the parallel forward pointer chasing (PFPC) algorithm and the index-splitting parallel algorithm (IndexSplit)] when computing path expressions with restrictive predicates, and that the right-deep zigzag tree scheduling strategy has a better performance than the right-deep tree scheduling strategy.