YAXQL : A powerful and web-aware query language supporting query reuse and data integration

Since XML seems to be the next great wave on the web, several query languages for XML have been proposed. Unfortunately, none of these proposals comes even close to meet the requirements for such a query language. We review the requirements for a query language for XML and propose a new query language, YAXQL, which meet them

The Evaluation of Content-Based Web Queries

We introduce the notions of syntactically and semantically structured data to refine the notion of semi-structured data. As we will see, most data found on the Web is syntactically structured. In order to evaluate content-based Web queries, semantically structured data is needed. The problem occurs to transform syntactically structured data into semantically structured data. Syntactically and semantically structured data can be represented by trees. Our main contribution is a powerful restructuring mechanism that allows to express the transformation of trees representing syntactically structured data to trees that represent semantically structured data. We embed our restructuring mechanism into RAW (Relational Algebra for the Web) and demonstrate its expressiveness by several example queries

Anatomy of a Native XML Base Management System

Several alternatives to manage large XML document collections exist, ranging from file systems over relational or other database systems to specifically tailored XML repositories. In this paper we give a tour of Natix, a database management system designed from scratch for storing and processing XML data. Contrary to the common belief that management of XML data is just another application for traditional databases like relational systems, we illustrate how almost every component in a database system is affected in terms of adequacy and performance. We show how to design and optimize areas such as storage, transaction management comprising recovery and multi-user synchronisation as well as query processing for XML

Algebraic XML Construction and Its Optimization in Natix

While using an algebra that acts on sets of variable bindings for evaluating XML queries, the problem of constructing XML from these bindings arises. One approach is to define a powerful operator that is able to perform a complex construction of a representation of the XML result document. The drawback is that such an operator in its generality is hard to implement and disables algebraic optimization since it has to be executed last in the plan. Therefore we suggest to construct XML documents by special query execution plans called construction plans built from simple, easy to implement and efficient operators. The paper proposes four simple algebraic operators needed for XML document construction. Further, we introduce an optimizing translation algorithm of construction clauses into algebraic expressions and briefly point out algebraic optimizations enabled by our approach

RAW: A Relational Algebra for the Web

The main idea underlying the paper is to extend the relational algebra such that it becomes possible to process queries against the World-Wide Web. These extensions are minor in that we tried to keep them at the domain level. Additionally to the known domains (int, bool, float, string), we introduce three new domains to deal with URLs, html-documents or fragments thereof, and path expressions. Over these domains we define several functions that are accessible from the algebra within the subscripts of the relational operators. The approach allows us to reuse the operators of the relational algebra without major modifications. Indead, the only extension necessary is the introduction of a map operator. Further, two modifications to the scan and the indexscan are necessary. Finally, the indexscan which has the functionality of a typical meta-search engine is capable of computing a unified rank based on the tuple order provided by the underlying search engines. 1 Introduction The Web [2] w..

Noname manuscript No. (will be inserted by the editor) Anatomy of a Native XML Base Management System

The date of receipt and acceptance will be inserted by the editor Abstract Several alternatives to manage large XML document collections exist, ranging from file systems over relational or other database systems to specifically tailored XML base management systems. In this paper we give a tour of Natix, a database management system designed from scratch for storing and processing XML data. Contrary to the common belief that management of XML data is just another application for traditional databases like relational systems, we illustrate how almost every component in a database system is affected in terms of adequacy and performance. We show how to design and optimize areas such as storage, transaction management comprising recovery and multi-user synchronization as well as query processing for XML. Key words XML, database