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arXiv 2102.11796cs.DB
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带属性级边界的复杂系统的有效不确定性跟踪(扩展版)

Efficient Uncertainty Tracking for Complex Queries with Attribute-level Bounds (extended version)

Su Feng, Aaron Huber, Boris Glavic, Oliver Kennedy

摘要:

某些答案是处理许多实际数据管理任务中出现的不确定性的原则性方法。不幸的是,这种方法是昂贵的,可能会排除有用的(如果不确定)答案。之前的工作介绍了不确定性注释数据库(UA-DB),它结合了某些答案的欠近似和过近似。UA-DB将基于不完全K关系的某些答案的可靠性与经典确定性数据库系统的性能相结合。然而,UA-DB仅支持有限类别的查询,并且不支持属性级别的不确定性,这可能导致某些答案的不准确的欠近似。在本文中,我们介绍了属性注释的不确定数据库(AU-DBs),扩展了UA-DB模型与属性级注释,记录所有可能的世界的属性值的界限。这使得不完整的数据库更精确的近似。此外,我们扩展UA-DB编码一个紧凑的过度近似的可能的答案,这是必要的,以支持非单调查询,包括聚合和设置差异。我们证明了AU-DBs的查询处理保留了某些和可能的答案的界限,并研究了压缩中间结果以保持效率的算法。通过对可能的答案进行紧凑编码,我们的方法还为处理缺失数据提供了坚实的基础。使用以准确性换取性能的优化,我们的方法可以扩展到复杂的查询和大型数据集,并产生准确的结果。此外,它显着优于不确定的数据管理的替代方法。

英文摘要:

Certain answers are a principled method for coping with the uncertainty that arises in many practical data management tasks. Unfortunately, this method is expensive and may exclude useful (if uncertain) answers. Prior work introduced Uncertainty Annotated Databases (UA-DBs), which combine an under- and over-approximation of certain answers. UA-DBs combine the reliability of certain answers based on incomplete K-relations with the performance of classical deterministic database systems. However, UA-DBs only support a limited class of queries and do not support attribute-level uncertainty which can lead to inaccurate under-approximations of certain answers. In this paper, we introduce attribute-annotated uncertain databases (AU-DBs) which extend the UA-DB model with attribute-level annotations that record bounds on the values of an attribute across all possible worlds. This enables more precise approximations of incomplete databases. Furthermore, we extend UA-DBs to encode an compact over-approximation of possible answers which is necessary to support non-monotone queries including aggregation and set difference. We prove that query processing over AU-DBs preserves the bounds of certain and possible answers and investigate algorithms for compacting intermediate results to retain efficiency. Through an compact encoding of possible answers, our approach also provides a solid foundation for handling missing data. Using optimizations that trade accuracy for performance, our approach scales to complex queries and large datasets, and produces accurate results. Furthermore, it significantly outperforms alternative methods for uncertain data management.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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