Some Experimental Results on Distributed Join Algorithms in a Local Network

This paper presents some experimental results on the performance of distrihuted join algorithms in a local nctwol-k. Eight different join methods have been implemented in an experimental distrihuted system, the Cryseal multicomputcr, and tested for join queries with a variety of relation sizes, join selcctivitics, and join column value distributions. The results obtained indicate that pipelined join methods outperform sequential methods over a wide range of join queries. II was also found that the communications costs in a local network environment arc not a dominant factor with rcspcct IO performance, and that shipping a whole relation from one site to another is not an unreasonahlc dccison as long as it is done in the framework 01‘ pipelined algorithms. l’wo pipelincd variants 01‘ a centralized nested loops join algorithm (with an index) wet-c found to perform well lor many oi ~hc queries tested.