Least common container of tree pattern queries and its applications
Author(s)
Wang, Junhu
Yu, Jeffrey Xu
Pang, Chaoyi
Liu, Chengfei
Griffith University Author(s)
Year published
2012
Metadata
Show full item recordAbstract
Tree patterns represent important fragments of XPath. In this paper, we show that some classes C of tree patterns exhibit such a property that, given a finite number of compatible tree patterns P1, . . . , Pn ? C, there exists another pattern P such that P1, . . . , Pn are all contained in P, and for any tree pattern Q ? C, P1, . . . , Pn are all contained in Q if and only if P is contained in Q.We experimentally demonstrate that the pattern P is usually much smaller than P1, . . . , Pn combined together. Using the existence of P above, we show that testing whether a tree pattern, P, is contained in another, Q ? C, ...
View more >Tree patterns represent important fragments of XPath. In this paper, we show that some classes C of tree patterns exhibit such a property that, given a finite number of compatible tree patterns P1, . . . , Pn ? C, there exists another pattern P such that P1, . . . , Pn are all contained in P, and for any tree pattern Q ? C, P1, . . . , Pn are all contained in Q if and only if P is contained in Q.We experimentally demonstrate that the pattern P is usually much smaller than P1, . . . , Pn combined together. Using the existence of P above, we show that testing whether a tree pattern, P, is contained in another, Q ? C, under an acyclic schema graph G, can be reduced to testing whether PG, a transformed version of P, is contained in Q without any schema graph, provided that the distinguished node of P is not labeled *.We then show that, under G, the maximal contained rewriting (MCR) of a tree pattern Q using a view V can be found by finding the MCR of Q using VG without G, when there are no *-nodes on the distinguished path of V and no *-nodes in Q.
View less >
View more >Tree patterns represent important fragments of XPath. In this paper, we show that some classes C of tree patterns exhibit such a property that, given a finite number of compatible tree patterns P1, . . . , Pn ? C, there exists another pattern P such that P1, . . . , Pn are all contained in P, and for any tree pattern Q ? C, P1, . . . , Pn are all contained in Q if and only if P is contained in Q.We experimentally demonstrate that the pattern P is usually much smaller than P1, . . . , Pn combined together. Using the existence of P above, we show that testing whether a tree pattern, P, is contained in another, Q ? C, under an acyclic schema graph G, can be reduced to testing whether PG, a transformed version of P, is contained in Q without any schema graph, provided that the distinguished node of P is not labeled *.We then show that, under G, the maximal contained rewriting (MCR) of a tree pattern Q using a view V can be found by finding the MCR of Q using VG without G, when there are no *-nodes on the distinguished path of V and no *-nodes in Q.
View less >
Journal Title
Acta Informatica
Volume
49
Issue
3
Subject
Theory of computation
Data management and data science
Database systems