An adaptive hash join algorithm on a network of workstations

Due to advances in computer technology, many organizations have a large number of workstation-class machines connected by LAN. Such a network of workstations (NOW) can be used for parallel processing, including database query processing. This paper proposes a new load sharing algorithm for hash join processing on NOWs. This new algorithm combines a chunking method with hash join to manage dynamic changes that occur in NOW environments. The algorithm is compared with two other algorithms: an adaptive nested-loop join and adaptive GRACE hash join. These three algorithms were evaluated on a Pentium-based heterogeneous NOW system with skewed data and various non-query background loads. The results show that the new algorithm is the best among the three in most of the cases and should be used for single join processing on NOWs.