XML is widely used for representing and exchanging hierarchical data and queries naturally specify hierarchical patterns to select relevant parts of an XML document. These patterns have a sequence of selection predicates connected by operators representing structural relationships (ancestor-descendant or preceding-following sibling). In this context, the operation of structural join involves discovering pairs of nodes that are structurally related from the cross product of two sets of nodes.
Current XPath processing algorithms focus more on solving the queries containing ancestor-descendant relationship but pay little attention to the equally important preceding-following sibling axes. In this paper, we propose a new solution for processing queries containing sibling axes by using a sibling-list at every level of the XML document tree. We show that using sibling-lists the time complexity of the proposed join algorithms is linear in the sum of lengths of input lists. An extensive experimental evaluation shows that our join algorithms perform significantly better than the currently existing sibling join algorithms.