A Case Study For Distributed Query Processing

(i) (ii) (is) In the integrated strategy, one component decides which relation should remain fragmented at different sites. The other component decides which local operations, selections and projections, should be performed before the join operations. Our experimental results reveal that the choices made by the integrated algorithm in deciding which relation should remain fragmented and which local operations to be performed are valid. More precisely , the response times of queries processed by the algorithm are lower than those of the same queries processed using other strategies. These experimental results agree with the analytic cost model which we have previously proposed [YGC87]. In addition, our experiments provide insight on the relative cost VO, network, and processing cost in a real environment. This enables us to identify timeconsuming operations in distributed query processing, and suggest ways to improve perforniance.