The Effects of Bytecode Generation in XSLT and XQuery
O'Neil Davion Delpratt
This paper attempts to analyze the performance benefits that are achievable by adding a code generation phase to an XSLT or XQuery engine. This is not done in isolation, but in comparison with the benefits delivered by high-level query rewriting. The two techniques are complementary and independent, but can compete for resources in the development team, so it is useful to understand their relative importance. We use the Saxon XSLT/XQuery processor as a case study, where we can now translate the logic of queries into Java bytecode. We provide an experimental evaluation of the performance of Saxon with the addition of this feature compared to the existing Saxon product. Saxon's Enterprise Edition already delivers a performance benefit over the open source product using the join optimizer and other features. What can we learn from these to achieve further performance gains through direct byte code generation?