AReNA: adaptive distributed catalog infrastructure based on relevance networks
VLDB '05 Proceedings of the 31st international conference on Very large data bases
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Recent technology advances have enabled mediated query processing with Internet accessible WebSources. A characteristic of WebSources is that their access costs exhibittransient behavior. These costs depend on the network and server workloads, which are often affected by the time of day, day, etc. Given transient behavior, an appropriate performance target (PT) for a noisy environment will correspond to "at least X percentage of queries will have a latency of less than T units of time". In this paper, we propose an optimizer strategy that is sensitive to the objective of meeting such performance targets (PT). For each query plan, a PT sensitive optimizer uses both the expected value of the cost distribution of the plan, as well as the expected delay of the plan. We validate our strategy using a simulation based study of the optimizer's behavior. We also experimentally validate the optimizer using traces of access costs for real WebSources.