T-SIX: An Indexing System for XML Siblings

We present a system for efficient indexed querying of XML documents, enhanced with sibling operations. R-tree index proposed in [5] has a very high cost for the following-sibling and precedingsibling axes. We develop a family of index structures, which we refer to as transformed split-tree indexes, to address this problem, in which (i) XML data is horizontally split by a simple, yet efficient criteria, (ii) the split value is associated with tree labeling, (iii) all data elements are transformed into new dimensions to avoid possible overlap between bounding boxes representing data elements in the split tree. The T-SIX system incorporates building transformed split-tree index for XML documents as well as query processing on all XPath axes to provide query answers.