| With the growing popularity and application of XML related standards,large repositories of XML documents have emerged on the Web.It is necessary to store these documents into a database to make them manageable.Storage schemes have become an important research topic in the XML data management field. Native XML database could take into account the characteristics of XML data fully,deal with the XML data in a natural way,support storage and query well in all aspects,and achieve good results.Therefore,the native XML database storage means a great deal of research value.This thesis is based on acknowledge of XML and relation database, analyzes the storing method of XML data in native XML database and researches depply native XML database Natix. But there are still some problems:records often have to save a certain number of "structure information" to ensure the accuracy of the data reduction,this makes that records are not independent of each other,and no independence between the records will affect the efficiency of updating XML.This thesis improves Natix according to inadequacies of the system,named the improved Natix system NatixUp. So while keeping the structure relation between the nodes, NatixUp also does the following things:in order to query the information of the node structure facilitately and support for updating XML file effectively,in this thesis, a new coding scheme is proposed,which is named as prefix division coding scheme; the records are independent, which can reduce the modification to the storage data and index after update, that we can reduce the update cost; a new update algorithm which is based on the space usage ratio and a new split-tree algorithm which is based on the relationship between father and son clustering.In theory,NatixUp system can support the updates effectively.At last, this thesis verifies the improvement of the NatixUp system through experiments. The results show that the NatixUp system has better Update efficiency compared with the Natix system. |
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