| 摘要 |
In decision support applications, the ability to provide fast approximate answers to aggregation queries is desirable. A disclosed technique for approximate query answering is sampling. For many aggregation queries, appropriately constructed biased (non-uniform) samples can provide more accurate approximations than a uniform sample. The optimal type of bias, however, varies from query to query. An approximate query processing technique is used that dynamically constructs an appropriately biased sample for each query by combining samples selected from a family of non-uniform samples that are constructed during a pre-processing phase. Dynamic selection of appropriate portions of previously constructed samples can more accurate approximate answers than static, non-adaptive usage of uniform or non-uniform samples.
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