Abstract. In this paper we investigate the feasibility and efficiency of mapping XML data and access control policies onto relational and native XML databases for storage and querying. We developed a re-annotation algorithm that computes the XPath query which designates the XML nodes to be re-annotated when an update operation occurs. The algorithm uses XPath static analysis and our experimental results show that our re-annotation solution is on the average 7 times faster than annotating the entire document.