An Object � Based Approach for E ective XML Data Storage

XML data storage is a critical issue due to the so called I O bottleneck problem emerged in nowdays computer systems This paper presents an object based XML data representation model towards e ec tive XML data placement The proposed representation of XML docu ments is analysed in a two level scheme the external level is based on the structure of a browsing graph whereas the internal level is supported by a tree like structure The main contribution of the paper is that it ex ploits the object data model in order to consider XML data dependencies access frequencies and constraints A simulation model has been devel oped in order to evaluate di erent XML data placement strategies and the impact of the proposed representation model in the overall storage process XML data placement is applied on a tertiary storage subsystem by either constructive or iterative placement techniques Three popular policies the Organ pipe the Camel and the Simulated Annealing algo rithms have been considered and experiments have been carried out on synthetic workloads of XML data sets The need of applying an XML data storage policy is apparent as indicated by the resulted improve ments in seek and service times The Simulated Annealing approach has been proven to outperform the other XML data placement strategies Index terms XML data storage XML data representation model ter tiary storage subsystems XML data placement algorithms