A Bottom-up Algorithm for XML Twig Queries

Twig query is a core operation in processing and optimizing XML structural queries. Recently, various algorithms have been proposed for finding twig patterns efficiently. Most of them are based on region labeling, pay little attention on nodes level information, and require additional caches such as stacks or lists to maintain the intermediate matching results, which cause the performance bottleneck of these algorithms. In contrast to previous work, we present a bottom-up algorithm for twig queries, which does not require additional caches and introduces idea of string searching to determine binary relationship between two nodes. Be- sides, this paper presents a node filtering mechanism–PathLevel, which can also be used in other algorithms for speeding up the query. Comprehensive experiments on several datasets demonstrate our method is an effective way for twig query.