Element classification‐based transformation of XML queries

Engines have been built that execute queries against XML data. The aim of this paper is to describe a novel technique that can be used to improve the speed of execution of the queries based on semantics of the data in the XML document.

The paper formally introduces algorithms for optimizing XML queries, implement the algorithms, and through experimentation demonstrate the improvement in speed.

Three possible semantic query optimizations based on the values of elements were introduced and these demonstrate that two of the three optimizations improve query performance but the third does not. It is hypothesized why this is the case.

A limitation is obviously the query engine and how it works. Future work includes, executing the experiments on a different engine and comparing results, building a system to automatically generate the characteristics that are necessary to do the optimization, describing the best way to represent and maintain the characteristics once they are found, compare the results of optimizations based on content with optimizations based on structure.

The optimizations could be incorporated into new query engines.

Novel algorithms for query optimization have been developed and proven to work. They are of value to people who are building database systems for XML data.