We give two sufficient conditions on XPath like languages for having first order expressivity, meaning that every first order definable set of paths in an ordered node-labeled tree is definable in that XPath language. They are phrased in terms of expansions of navigational (sometimes called “Core”) XPath. Adding either complementation, or the more elegant conditional paths is sufficient. A cond...

Providing efficient access to XML documents becomes crucial in XML database systems. More and more concurrency control protocols for XML database systems were proposed in the past few years. Being an important language for addressing data in XML documents, XPath expressions are the basis of several query languages, such as XQurey and XSLT. In this paper, we propose a lock-based concurrency cont...

The popularity of XML has motivated the development of novel XML processing tools many of which embed the XPath language for XML querying, transformation, constraint specification, etc. XPath developers (as well as less technical users) have access to commercial tools to help them use the language effectively. Example tools include debuggers that return the result of XPath subexpressions visual...

This paper presents the METAXPath data model and query language. METAXPath extends XPath with support for XML metadata. XPath is a specification language for locations in an XML document. It serves as the basis for XML query languages like XSLT and the XML Query Algebra. The METAXPath data model is a nested XPath tree. Each level of metadata induces a new level of nesting. The data model separa...

This paper presents the METAXPath data model and query language. METAXPath extends XPath with support for XML metadata. XPath is a specification language for locations in an XML document. It serves as the basis for XML query languages like XSLT and the XML Query Algebra. The METAXPath data model is a nested XPath tree. Each level of metadata induces a new level of nesting. The data model separa...

Masahiro Hori IBM Tokyo Research Laboratory 1623-14 Shimotsuruma, Yamato, Kanagawa 242-8502 Japan email [email protected] ABSTRACT Web metadata is crucial for providing machine-understandable descriptions of Web resources, and has a number of applications such as discovery, qualification, and adaptation of Web contents. While metadata is often embedded into a target document, metadata can also b...

Various techniques have been proposed for efficient evaluation of XPath expressions, where the XPath location steps are rooted in a single sequence of context nodes. Among these techniques, the staircase join allows to evaluate XPath location steps along arbitrary axes in at most one scan over the XML document, exploiting the XPath accelerator encoding (aka. pre/post encoding). In XQuery, howev...

We present a novel streaming algorithm for evaluating XPath expressions that use backward axes (parent and ancestor) and forward axes in a single document-order traversal of an XML document. Other streaming XPath processors, such as YFilter, XTrie, and TurboXPath handle only forward axes. We show through experiments that our algorithm significantly outperforms (by more than a factor of two) a t...

This paper discusses the validity problem for positive XPath queries with wildcard in the presence of DTDs. A given XPath query p is valid under a DTD D if, for every XML document T conforming to D, the answer to p on T is nonempty. The validity problem is one of the basic static analyses of queries, together with the satisfiability and the containment problems. Although the validity problem is...

—Indexing technology is one of the kernel technologies in database management systems, especially for large datasets. XML (eXtensible Markup Language) has been successfully adopted as a universal data exchange format, particularly in the WWW environment. It is an important and basic task to efficiently implement XPath axes on XML documents. Using R*-tree, T. Grust proposed an interesting method...