Research on processing XML documents gained much activity in recent times. XML query languages are mostly based on XPath expressions, which are used to select parts of XML documents. So, methods defining semantics for XPath expressions are of special importance. In the paper we propose a relational semantics for XPath expressions. The semantics consists of four semantic functions defined over s...

We present a major revision of the XPath benchmark known as XPathMark [1]. The new version splits into a functional test over a small educational document and a more elaborated performance test over XMark [2] documents. We conclude by sharing with the reader our experience on running XPathMark on some popular XSLT/XQuery processors. 1 Functional and Performance Tests for XPath The new release o...

We present BLAS, a Bi-LAbeling based XPath processing System. BLAS uses two labeling schemes to speed up query processing: P-labeling for processing consecutive child (or parent) axis traversals, and D-labeling for processing descendant (or ancestor) axis traversals. XML data are stored in labeled form and indexed. Algorithms are presented for translating XPath queries to SQL expressions. BLAS ...

Within mobile client-server applications which access a server-side XML database, XPath expressions play a central role in querying for XML fragments. Whenever the mobile client can use a locally stored previous query result in order to answer a new query instead of accessing the server-side database, this can significantly reduce the data transfer from the server to the client. In order to che...

As a simple XML query language but with enough expressive power, XPath has become very popular. To expedite evaluation of XPath queries, we consider the problem of caching results of popular XPath queries to answer queries. Existing semantic caching systems can answer queries that have been already cached, but can’t combine cached results of multiple XPath queries to answer new queries. In this...

The study of node-selection query languages for (finite) trees has been a major topic in the recent research on query languages for Web documents. On one hand, there has been an extensive study of XPath and its various extensions. On the other hand, query languages based on classical logics, such as first-order logic (FO) or monadic second-order logic (MSO), have been considered. Results in thi...

We describe the design and preliminary analysis of an optimization technique for XPath called warp-edge optimization. The XPath data model is a tree-like data model that has an edge from an element to each component in the content of that element. The edges are traversed in the evaluation of an XPath expression. A warp edge is an edge that is something other than a parent to child edge, i.e., a...

We motivate and present a definition of optimal buffering for streaming evaluation of XPath queries. We consider a large fragment of XPath that includes multiple (correlated) subqueries and reverse (up the document tree) axes. We describe a method for XPath evaluation with optimal buffering. We present the results of an experimental evaluation of our methods based on our implementation, which i...

We show how the context state of XPath, accessed through the position() and last() pseudo-functions, can be eliminated in most cases by translating references to the context state with an equivalent contextfree expression, and how this enables the use of context state in combination with a subsequent “forward-only” transformation, allowing for execution of (almost) full XPath on any of the emer...