Many research projects have focused on providing efficient storage for XML repositories. Our focus in this chapter has been on filtering and adapting XML documents according to user requirements before storing them.
In this chapter, we have presented a global approach for designing and managing an XML data warehouse. We have proposed a view model and a graphical tool for the data warehouse specification. Views defined in the warehouse allow filtering and restructuring of XML sources. The warehouse is defined as a set of materialized views and provides a mediated schema that constitutes a uniform interface to querying the XML data warehouse. We have also proposed mapping techniques using a relational DBMS. This mapping allows us to store XML data without redundancies and then optimizes storage space. Finally, our approach has been implemented in a complete system named DAWAX.
We are planning to investigate two main research issues. First, we plan to improve the maintenance strategy. In the context of monitored XML sources, we plan to develop an incremental maintenance technique. Second, we plan to investigate query-rewriting techniques to enhance the capabilities of the query manager. This technique will benefit from the mapping schema that we have presented here.