XQuery algebra

Abstract

This diploma thesis deals with design and implementation of a processor of the XQuery computer language used for searching data in tree organized XML documents and databases. The goal of this work is to design and create a processor based on algebraic operators which can give better performance in evaluation of the input queries than direct interpretation.

At the beginning of this work a breaf overview of currently used technologies for querying XML including a short description of the XQuery language is given. It is followed by a proposal of algebraic operators and proposal of compilation rules transforming queries into those operators. There are also included optimization techniques enabling to make such modifications in the compiled query as the result is preserved, but the evaluation is more effective. Those proposals are subsequently transformed into the real form of processor implementation. The final part of this work compares the implemented processor to other existing and commonly used implementations.