Twig Pattern Minimization Based on XML Schema Constraints

Twig pattern is one of the core components of XQuery. Twig usually includes redundancy nodes which can be optimized. Schema feature is used to judge whether the node of Twig pattern is redundancy. In this paper, we propose sufficient Schema constraints and specific rules. In this paper, we have designed more determination conditions to optimize, then we will get the most efficient results. By a large number of test case, we finally get the practical limits of minimization.

Matching of Twig Pattern with AND/OR Predicates over XML Streams

Chapter 5 presents a novel approach for processing complex twig pattern with OR-predicates and AND-predicates over XML document streams which a twig pattern is represented as a query tree. Its OR-predicates and AND-predicates are represented as a separate abstract syntax tree associated with the branch node, and all the twig patterns are combined into a single prefix query tree that represents such queries by sharing their common prefixes. Consequently, all the twig patterns are evaluated in a single, document-order pass over the input document stream avoiding the translation of the set of twig patterns into a finite state automaton. Chapter 1 introduces the background of this issue. Chapter 2 discusses the representation of complex twig pattern as a query tree, how to combine a set of twig patterns into a single query three, how to match multi twig patterns over the incoming XML document, and possible optimization of computing logical AND/OR predicates. In section 3, the architecture of a XML stream process system named LeoXSQ is given. Section 4 shows the conducted experiments. In section 5, the related work is discussed. Section 6 summarizes this chapter.