Evaluating XPath Queries on XML Data Streams

Whenever queries have to be evaluated on XML data streams or when the memory that is available to evaluate the XML data is relatively small compared to the document DOM based approaches that have to load and store large parts of the document in main memory will fail. In comparison, we present an approach to evaluate XPath queries on SAX streams that supports all axes of core XPath, including the sibling axes. Starting from the XPath query, our approach generates a stack of automata that uses the SAX stream as input and generates the result of the query as an output SAX stream. An evaluation of our implementation shows that in general our approach needs less main memory, but at the same time is faster than both, Saxon and YFilter.