Fast Matching of Twig Patterns

Abstract

Twig pattern matching plays a crucial role in data processing. Existing twig pattern matching algorithms can be classified into two-phase algorithms and one-phase algorithms. While the two-phase algorithms (e.g., ) suffer from expensive merging cost, the one-phase algorithms (e.g., , , ) either lack efficient filtering of useless elements, or use over-complicated data structures. In this paper, we present two novel one-phase holistic twig matching algorithms, TwigMix and , which combine the efficient selection of useful elements (introduced in ) with the simple lists for storing final solutions (introduced in ). simply introduces the element selection function of into to avoid manipulation of useless elements in the stack and lists. further improves this by introducing some pointers in the lists to completely avoid the use of stacks. Our experiments show significantly and consistently outperforms and (up to several times faster), and is up to two times faster than .