Incremental maintenance of views with duplicates

Griffin, Timothy G.; Libkin, Leonid

doi:10.1145/223784.223849

Cited by 185 publications

(123 citation statements)

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“…Maintaining query answers has been considered under both the set [6,7] and bag [8,14] relational algebra. Generally, given a query on N relations Q(R1, .…”

Section: A Brief Survey Of Ivm Techniquesmentioning

confidence: 99%

“…, RN ) for each input relation Ri in turn. The creation of delta queries has been studied for query languages with aggregation [25] and bag semantics [14], but we know of no work that investigates delta queries of nested and correlated subqueries. [17] has considered view maintenance in the nested relational algebra (NRA), however this has not been widely adopted in any commercial DBMS.…”

Section: A Brief Survey Of Ivm Techniquesmentioning

confidence: 99%

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DBToaster: higher-order delta processing for dynamic, frequently fresh views

et al. 2014

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Applications ranging from algorithmic trading to scientific data analysis require realtime analytics based on views over databases that change at very high rates. Such views have to be kept fresh at low maintenance cost and latencies. At the same time, these views have to support classical SQL, rather than window semantics, to enable applications that combine current with aged or historical data.In this paper, we present viewlet transforms, a recursive finite differencing technique applied to queries. The viewlet transform materializes a query and a set of its higher-order deltas as views. These views support each other's incremental maintenance, leading to a reduced overall view maintenance cost. The viewlet transform of a query admits efficient evaluation, the elimination of certain expensive query operations, and aggressive parallelization. We develop viewlet transforms into a workable query execution technique, present a heuristic and cost-based optimization framework, and report on experiments with a prototype dynamic data management system that combines viewlet transforms with an optimizing compilation technique. The system supports tens of thousands of complete view refreshes a second for a wide range of queries.

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“…Maintaining query answers has been considered under both the set [6,7] and bag [8,14] relational algebra. Generally, given a query on N relations Q(R1, .…”

Section: A Brief Survey Of Ivm Techniquesmentioning

confidence: 99%

Section: A Brief Survey Of Ivm Techniquesmentioning

confidence: 99%

DBToaster: higher-order delta processing for dynamic, frequently fresh views

et al. 2014

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“…Later efforts on more complex view definitions including duplicates [8] or aggregations [19,16] and also object-oriented views [2] often have instead taken an algebraic approach. Unnesting and restructuring of data is core even in the simplest XQuery view definitions due to the nested structure of XML data.…”

Section: State-of-the-art On View Maintenancementioning

confidence: 99%

“…The algebraic approach, illustrated in Figure 1.3, is therefore the appropriate foundation for tackling incremental view maintenance in the XML context. As pointed out in [8], the main advantages of an algebraic approach to view maintenance include:…”

Section: State-of-the-art On View Maintenancementioning

confidence: 99%

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Order-Sensitive View Maintenance of Materialized XQuery Views

Dimitrova

Elsayed

Rundensteiner

2003

Conceptual Modeling - ER 2003

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Materialized XML views are a popular technique for integrating data from possibly distributed and heterogeneous data sources. However, the problem of the incremental maintenance of such XML views poses new challenges which to date remain unaddressed.One, XML views not only filter the data, but may radically restructure it to construct new XML nested document structures. Moreover, order is inherent in the XML model, and XML views reflect both the implicit document order of the underlying sources and the order explicitly imposed in the view definition. Therefore, order also has to be preserved at view maintenance time.In this thesis we present an algebraic approach for the incremental maintenance of XQuery views, called VOX (View maintenance for Ordered XML). To the best of our knowledge, this is the first solution to order-preserving XML view maintenance. Our strategy correctly transforms an update to source XML data into sequences of updates that refresh the view. Our technique is based on an algebraic representation of the XQuery view expression using an XML algebra. The XML algebra has ordered bag semantics; hence most of the operators logically are order preserving. We propose an order-encoding mechanism that migrates the XML algebra to (non-ordered) bag semantics, no longer requiring most of the operators to be order-aware. Furthermore, this now allows most of the algebra operators to become distributive over update operations. This transformation brings the problem of maintaining XML views one step closer to the problem of maintaining views in other (unordered) data models. We are thus now able to adopt some of the existing (relational) maintenance techniques towards our goal of efficient order-sensitive XQuery view maintenance. In addition we develop a full set of rules for propagating updates through XML specific operations. We have proven the correctness of the VOX view maintenance approach. A full implementation of VOX on top of RAINBOW, the XML data management system developed at WPI, has been completed. Our experimental results, performed using the data and queries provided by the XMark benchmark, confirm that incremental XML view maintenance indeed is significantly faster than complete recomputation in most cases. Incremental maintenance is shown to outperform recomputation even for large updates.ii Acknowledgements First, I would like to express my sincere appreciation and gratitude to my advisor Prof. Elke Rundensteiner for her help, guidance, support and encouragement. Without her feedback, ideas, suggestions, incredible responsiveness and the time she always had for me, this thesis would not have been achieved. I would also like to thank her for guiding me throughout my graduate studies.I thank my reader, Prof. Carolina Ruiz for her valuable feedback.

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