Christian Grün

XQuery Full Text Implementation in BaseX

BaseX is an early adopter of the upcoming XQuery Full Text Recommendation. This paper presents some of the enhancements made to the XML database to fully support the language extensions. The systems data and index structures are described, and implementation details are given on the XQuery compiler, which supports sequential scanning, index-based, and hybrid processing of full-text queries. Experimental analysis and an insight into visual result presentation of query results conclude the presentation.

MedioVis – a user-centred library metadata browser

MedioVis is a visual information seeking system which was designed especially for library data. The objective target was to create a system which simplifies and optimizes the users information seeking process and thus further motivates the user to browse in the library stock. To enhance the motivation special attention was given to consider joy of use aspects during the design of the user interface. The primary user interface design is based on multiple coordinated views to offer a great variety of exploration possibilities in a direct-manipulative manner. To accomplish a self-explanatory usability of the system for non-expert users, the development was accompanied by continuous user tests with casual and regular library users. At the end of the development process a comprehensive summative evaluation was conducted, comparing efficiency and joy of use of the existing web-based catalogue system KOALA of the library of the University of Konstanz with the MedioVis system. The results of this comparative evaluation show a significant improvement of the efficiency of the information seeking process with the help of MedioVis. The users also rated MedioVis significantly better in all dimensions of its hedonic quality and appeal compared with KOALA.

HyperGrid - Accessing Complex Information Spaces

In this paper, we describe a new interaction and visualization concept for non-expert users to easily access complex heterogeneous information spaces. The HyperGrid combines well-known table visualizations with zoomable user interface concepts to provide a two-dimensional grid as an access tool to multi-dimensional and relational data. It allows the presentation of attributes of multiple data types, various modalities and various levels of detail in a compact and consistent visual structure. Our concept is illustrated by a use-case based on our experiences and evaluations from preceding projects in the field of visual information seeking systems.

BaseX & DeepFS joint storage for filesystem and database

Mere storage of personal data in state-of-the-art filesystems is a markedly well done job in current operating systems. Convenient access to and information retrieval from such data, however, is crucial to leverage the stored information. Thereby database style query languages can be of great use. We demonstrate a user level filesystem implementation that is built on recent semi-structured database storage techniques. As such, it serves as a storage layer for the BaseX XQuery processor and, while it appears to the operating system as a conventional filesystem, a large part of its content can be queried using XPath/XQuery.

Efficient structural bulk updates on the Pre/Dist/Size XML encoding

In order to manage XML documents, native XML databases use specific encodings that map the hierarchical structure of a document to a flat representation. Several encodings have been proposed that differ in terms of their support for certain query workloads. While some encodings are optimized for query processing, others focus on data manipulation. For example, the Pre/Dist/Size XML encoding has been designed to support queries over all XPath axes efficiently, but processing atomic updates in XML documents can be costly. In this paper, we present a technique, so-called structural bulk updates, that works in concert with the XQuery Update Facility to support efficient updates on the Pre/Dist/Size encoding. We demonstrate the benefits of our technique in a detailed performance evaluation based on the XMark benchmark.

A framework for retrieval and annotation in digital humanities using XQuery full text and update in BaseX

A key difference between traditional humanities research and the emerging field of digital humanities is that the latter aims to complement qualitative methods with quantitative data. In linguistics, this means the use of large corpora of text, which are usually annotated automatically using natural language processing tools. However, these tools do not exist for historical texts, so scholars have to work with unannotated data. We have developed a system for systematic, iterative exploration and annotation of historical text corpora, which relies on an XML database (BaseX) and in particular on the Full Text and Update facilities of XQuery.

Function inlining in XQuery 3.0 optimization

Originally developed as a query language for XML databases, XQuery has evolved into a complete functional programming language. In order to unlock all optimization opportunities, XQuery processors therefore need to combine traditional query optimization with techniques used in optimizing compilers. In this paper, we discuss how the well-known technique of function inlining can be applied to XQuery. We present an implementation of function inlining based on the query processor of BaseX, an open-source XML database. Finally, a detailed quantitative evaluation demonstrates that the performance benefits obtained by blending compiler and query optimizer techniques surpass results from any one single technique.