How to query XML documents to extract and restructure the information is an important issue in XML research. Currently, XQuery based on XPath is the most promising standard of W3C. In this paper, we introduce a new set of syntax rules called XTree, which is a generalization of XPath. XTree has a tree structure, and a user can bind multiple variables in one XTree expression. It explicitly identi...

In this paper we present Regular XPath (RXPath), which is a natural extension of XPath with regular expressions over paths that has the same computational properties as XPath: linear-time query evaluation and exponential-time reasoning. To establish these results, we devise a unifying automata-theoretic framework based on two-way weak alternating tree automata. Specifically, we consider automat...

We propose a novel index structure, termed XTrie, that supports the efficient filtering of XML documents based on XPath expressions. Our XTrie index structure offers several novel features that make it especially attractive for largescale publish/subscribe systems. First, XTrie is designed to support effective filtering based on complex XPath expressions (as opposed to simple, single-path speci...

C-store environment uses a relational database for storing table tuples on the disk by columns. Can it be effectively used as XML database? This paper considers XML data without a schema. A two-level model of C-store based on XML-enabled relational databases is proposed. A measure of the model suitability is the possibility of evaluating effectively XPath queries. The XPath fragment considered ...

Many XML applications over the Internet favor high-performance single-pass streaming XPath evaluation. Finite automata-based algorithms suffer from potentially combinatorial explosion of dynamic states for matching descendant axes. We present QuickXScan for streaming evaluation of XPath queries containing child and descendant axes with complex predicates. Using a tree representation for an XPat...

XPath satisfiability is one of the most basic problems of XML query optimization. A satisfiability decision framework, named SAT-DTD, is proposed to determine, given a set of XPath queries P and a DTD τ, which subset of P are satisfiable by an XML tree conforming to DTD τ. In the framework, an indexed NFA is constructed from the set of XPath queries P, and then the NFA is driven by simple API f...

This paper describes the design and implementation of an XML storage manager for fast and interactive XPath expressions evaluation. This storage manager has two main parts: the XML data storage structure and the index over this data. The system is designed in such a way that it minimizes the number of page reads for retrieving any XPath expression results while avoiding the shortcomings of prev...

As the number of applications that rely on XML data increases, so does the need for performing efficient XML query evaluation. A critical part of the solution involves providing new techniques for designing XML indexes and lookup algorithms. In this paper, we leverage the results of our research on coupling the partitions induced by fragments of XPath algebra and those induced by the structural...

We describe a method for the streaming evaluation of XPath queries that have subqueries in predicates. Our method rewrites XPath queries into a set of predicate-free labeled linear-form expressions (LFEs). These LFEs are used to generate a pushdown transducer that enables efficient management of a buffer and hierarchical index at runtime. To the best of our knowledge, our method is the first to...