Journal on Communications ›› 2014, Vol. 35 ›› Issue (7): 46-55.doi: 10.3969/j.issn.1000-436x.2014.07.006

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Efficiently computing RKN for keyword queries on XML data

HENZi-yang C1,2,ANGXuan W1,2(),ANGXian T3   

  1. 1 School of Information Science and Engineering, Yanshan University, Qinhuangdao 066004, China
    2 Key Laboratory for Computer Virtual Technology and System Integration of Hebei Province, Yanshan University, Qinhuangdao 066004, China
    3 School of Economics and Management, Yanshan University, Qinhuangdao 066004,China
  • Online:2014-07-25 Published:2017-06-24
  • Supported by:
    The National Natural Science Foundation of China;The National Natural Science Foundation of China;The National Natural Science Foundation of China;The Research Funds From Education Department of Hebei Province;The Science and Technology Research and Development Program of Hebei Province

Abstract:

Subtree results construction is a core problem in keyword query processing over XML data,for which com-puting the set of relevant keyword nodes (RKN) for each subtree's root node will greatly affect the overall system per-formance. Considering that existing methods cannot correctly identify RKN for ELCA semantics,the definitions of RKN and the RKN-Base algorithm were proposed,which can correctly judge whether a given node is an RKN of some ELCA node by sequentially scanning the set of inverted lists once. As RKN-Base cannot avoid processing all useless nodes,an optimized algorithm,namely RKN-Optimized,was then proposed,which computes RKN sets based on the set of ELCA nodes, rather than the set of inverted lists as RKN-Base does. As a result,RKN-Optimized avoids processing useless nodes, and reduces the time complexity. The experimental results verified the efficiency of the proposed algorithms.

Key words: XML, subtree results construction, ELCA, RKN

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