XQuery containment in presence of variable binding dependencies

Chen, Li; Rundensteiner, Elke A.

doi:10.1145/1060745.1060789

Cited by 10 publications

(5 citation statements)

References 19 publications

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“…We study caching inner queries in the streaming context and apply interval driven caching by using validity intervals as semantic descriptors. Semantic descriptors have also be shown to be of importance for query caching in the XML context [16], [17]. However, sophisticated cache matching algorithms had to be designed to deal with query containment, namely, with extracting related yet not identical subexpressions possibly with alternate hierarchical XML structures yet the same content [16].…”

Section: Related Workmentioning

confidence: 99%

Optimizing complex sequence pattern extraction using caching

Ray

Liu

Rundensteiner

et al. 2011

2011 IEEE 27th International Conference on Data Engineering Workshops

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Abstract-Complex Event Processing (CEP) has become increasingly important for tracking and monitoring complex event anomalies and trends in event streams emitted from business processes such as supply chain management to online stores in e-commerce. These monitoring applications submit complex event queries to track sequences of events that match a given pattern. The state-of-the-art CEP systems mostly focus on the execution of flat sequence queries, we instead support the execution of nested CEP queries specified by our NEsted Event Language NEEL. However, the iterative execution of nested CEP expressions often results in the repeated recomputation of the same or similar results for nested subexpressions as the window slides over the event stream. In this work we thus propose to optimize NEEL execution performance by caching intermediate results. In particular we design two methods of applying selective caching of intermediate results namely Object Caching and the IntervalDriven Semantic Caching. Techniques for incrementally loading, purging and exploiting the cache content are described. Our experimental study using real-world stock trades evaluates the performance of our proposed caching strategies for different query types.

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Section: Related Workmentioning

confidence: 99%

Optimizing complex sequence pattern extraction using caching

Ray

Liu

Rundensteiner

et al. 2011

2011 IEEE 27th International Conference on Data Engineering Workshops

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“…We study caching inner queries in the streaming context and apply interval driven caching by using validity intervals as semantic descriptors. Semantic descriptors have also be shown to be of importance for query caching in the XML context [22,23]. However, sophisticated cache matching algorithms had to be designed to deal with query containment, namely, with extracting related yet not identical subexpressions possibly with alternate hierarchical XML structures yet the same content [22].…”

Section: Related Workmentioning

confidence: 99%

Processing nested complex sequence pattern queries over event streams

Liu

Ray

Rundensteiner

et al. 2010

Proceedings of the Seventh International Workshop on Data Management for Sensor Networks

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Complex event processing (CEP) has become increasingly important for tracking and monitoring applications ranging from health care, supply chain management to surveillance. These monitoring applications submit complex event queries to track sequences of events that match a given pattern. As these systems mature the need for increasingly complex nested sequence queries arises, while the state-of-the-art CEP systems mostly focus on the execution of flat sequence queries only. In this paper, we now introduce an iterative execution strategy for nested CEP queries composed of sequence, negation, AND and OR operators. Lastly we have introduced the promising direction of applying selective caching of intermediate results to optimize the execution. Our experimental study using real-world stock trades evaluates the performance of our proposed iterative execution strategy for different query types.

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“…Because of their importance for query processing, a considerable amount of work has focused on the containment problem for tree-pattern queries in the presence and in the absence of schemas [9,14,19,32,20,10,6]. In particular, Neven and Schwentick [20] studied the complexity of treepattern queries (involving child and descendant relationships and wildcards) in the presence of disjunction and DTDs.…”

Section: Related Workmentioning

confidence: 99%

A heuristic approach for checking containment of generalized tree-pattern queries

Placek

Theodoratos

Souldatos³

et al. 2008

Proceedings of the 17th ACM Conference on Information and Knowledge Management

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Query processing techniques for XML data have focused mainly on tree-pattern queries (TPQs). However, the need for querying XML data sources whose structure is very complex or not fully known to the user, and the need to integrate multiple XML data sources with different structures have driven, recently, the suggestion of query languages that relax the complete specification of a tree pattern. In order to implement the processing of such languages in current DBMSs, their containment problem has to be efficiently solved.In this paper, we consider a query language which generalizes TPQs by allowing the partial specification of a tree pattern. Partial tree-pattern queries (PTPQs) constitute a large fragment of XPath that flexibly permits the specification of a broad range of queries from keyword queries without structure, to queries with partial specification of the structure, to complete TPQs. We address the containment problem for PTPQs. This problem becomes more complex in the context of PTPQs because the partial specification of the structure allows new, non-trivial, structural expressions to be inferred from those explicitly specified in a query. We show that the containent problem cannot be characterized by homomorphisms between PTPQs, even when PTPQs are put in a canonical form that comprises all derived structural expressions. We provide necessary and sufficient conditions for this problem in terms of homomorphisms between PTPQs and (a possibly exponential number of) TPQs. To cope with the high complexity of PTPQ containment, we suggest a heuristic approach for this problem that trades accuracy for speed. An extensive experimental evaluation of our heuristic shows that our heuristic approach can be efficiently implemented in a query optimizer.

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XQuery containment in presence of variable binding dependencies

Cited by 10 publications

References 19 publications

Optimizing complex sequence pattern extraction using caching

Optimizing complex sequence pattern extraction using caching

Processing nested complex sequence pattern queries over event streams

A heuristic approach for checking containment of generalized tree-pattern queries

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