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  • A Comprehensive Approach to 'Now' in Temporal Relational Databases: Semantics and Representation

    Author(s)
    Anselma, Luca
    Piovesan, Luca
    Sattar, Abdul
    Stantic, Bela
    Terenziani, Paolo
    Griffith University Author(s)
    Stantic, Bela
    Sattar, Abdul
    Year published
    2016
    Metadata
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    Abstract
    Now-related temporal data play an important role in many applications. Clifford et al.'s approach is a milestone to model the semantics of `now' in temporal relational databases. Several relational representation models for now-related data have been presented; however, the semantics of such representations has not been explicitly studied. Additionally, the definition of a relational algebra to query now-related data is an open problem. We propose the first integrated approach that provides both a neat semantics for now-related data and a compact 1NF representation (data model and relational algebra) for them. Additionally, ...
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    Now-related temporal data play an important role in many applications. Clifford et al.'s approach is a milestone to model the semantics of `now' in temporal relational databases. Several relational representation models for now-related data have been presented; however, the semantics of such representations has not been explicitly studied. Additionally, the definition of a relational algebra to query now-related data is an open problem. We propose the first integrated approach that provides both a neat semantics for now-related data and a compact 1NF representation (data model and relational algebra) for them. Additionally, our approach also extends current approaches to consider (i) domains where it is not always possible to know when changes in the world are recorded in the database and (ii) now-related data with a bound on their persistency in the future. To do so, we explicitly model the notion of temporal indeterminacy in the future for now-related data. The properties of our approach are also analyzed both from a theoretical (semantic correctness and reducibility of the algebra) and from an experimental point of view. Experiments show that, despite the fact that our approach is a major extension to current temporal relational approaches, no significant overhead is added to deal with `now'.
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    Journal Title
    IEEE Transactions on Knowledge and Data Engineering
    Volume
    28
    Issue
    10
    DOI
    https://doi.org/10.1109/TKDE.2016.2588490
    Subject
    Information and computing sciences
    Other information and computing sciences not elsewhere classified
    Publication URI
    http://hdl.handle.net/10072/100475
    Collection
    • Journal articles

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