QTPI:A quick terse path index for XML keyword search

The emergence of the Web has increased interests in XML data. XML query languages such as XQuery, XPath and NEXI, they use label paths to traverse the irregularly structured data. Without efficient indexes, query processing can be quite inefficient due to an exhaustive traversal on XML data. To overcome the inefficiency, we propose a novel index method, quick terse path index (named QTPI), which contain the content and structure of the XML documents. Unlike index methods that disassemble a query into multiple sub-queries, and then join the results of these sub-queries to provide the final answers, QTPI uses tree structures as the basic unit of query to avoid expensive join operations. Furthermore, QTPI provides a terse index that can quickly derive the keyword query and generate a set of effective structured queries by analyzing the given keyword query and scanning the index, hence it has a performance advantage over methods indexing either. We have conducted an experimental study on real-life XML data sets and the experimental results show that QTPI is effective, and efficient in supporting structural queries when compared with existing proposals.