Possible and Certain Answers for Queries over Order-Incomplete Data

Abstract : To combine and query ordered data from multiple sources, one needs to handle uncertainty about the possible orderings. Examples of such "order-incomplete" data include integrated event sequences such as log entries; lists of properties (e.g., hotels and restaurants) ranked by an unknown function reflecting relevance or customer ratings; and documents edited concurrently with an uncertain order on edits. This paper introduces a query language for order-incomplete data, based on the positive relational algebra with order-aware accumulation. We use partial orders to represent order-incomplete data, and study possible and certain answers for queries in this context. We show that these problems are respectively NP-complete and coNP-complete, but identify many tractable cases depending on the query operators or input partial orders.
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Contributor : Pierre Senellart <>
Submitted on : Wednesday, October 11, 2017 - 10:37:28 AM
Last modification on : Thursday, October 17, 2019 - 12:36:55 PM

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Antoine Amarilli, Mouhamadou Lamine Ba, Daniel Deutch, Pierre Senellart. Possible and Certain Answers for Queries over Order-Incomplete Data. 2017. ⟨hal-01614571⟩



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