Λεπτομέρειες

ΕίδοςΔημοσίευση
ΚωδικόςTR-2006-11
ΤίτλοςContainment of Partially Specified Tree-Pattern Queries
ΣυγγραφέαςΔημήτρης Θεοδωράτος, Θεόδωρος Δαλαμάγκας, Pawel Placek, Στέφανος Σουλδάτος, Τίμος Σελλής
Έτος2006
Λέξεις κλειδιά-
ΠερίληψηNowadays, huge volumes of data, including scientific data, are organized or exported in tree-structured form. Query- ing capabilities are provided through tree-pattern queries. The need for integrating multiple data sources with differ- ent tree structures has driven, recently, the suggestion of query languages that relax the complete specification of a tree pattern. In this paper we adopt a query language with partially spec- ified tree-pattern queries. A central feature of this type of queries is that the structure can be specified fully, par- tially, or not at all in a query. Important issues in query optimization require solving the query containment prob- lem. We study the containment problem for partially speci- fied tree-pattern queries. To support the evaluation of such queries, we use semantically rich constructs, called dimen- sion graphs, which abstract structural information of the tree-structured data. We address the problem of query con- tainment in the absence (absolute query containment) and in the presence (relative query containment) of dimension graphs, and we provide necessary and sufficient conditions for each type of query containment. We suggest a technique for relative query containment checking based on structural information extracted in advance from the dimension graph. Our approach is implemented and validated through exten- sive experimental evaluation.
ΚατηγορίαWWW and DBMS
Δημοσίευσηin Proceedings of the 5th Hellenic Data Management Symposium(HDMS'06), Thessaloniki, Greece, September 7-8, 2006
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