Rank-aware XML data model and algebra: towards unifying exact match and similar match in XML
Ning Wang, Xu De · 2007
Abstract: In this paper, we present rank-aware XML data model and algebra, which aims at providing a seamless support and integration of ranked queries with precise queries. Our data model is based on ranked XML trees by extending the semantics of XML trees to be rank-aware. A collection of ranked XML trees which can be ordered by their ranks is modeled as a sequence, which is the basis for ranked XML operations. With ranked XML tree model, we extend XML algebra by introducing new ranking operator and extending ordinary XML operators to fully support top-k queries. A set of algebraic laws is also defined in this paper for rewriting and optimizing top-k queries.