Normalized Storage Of XML Data

As the main standard for data representation and exchange on the Internet, the range of XML's application is very large , which requests more to XML database schema . Similar to relational database , if XML schema designing is not good , it will cause abnormity for inserting , deleting and updating data too , and the harm of XML data abnormity is further higher than relational data as Web is open.XML data has become mainsteam data on internet .There has already some achievement on correlation XML research , for example , the technology for storing , publishing , querying and optimizing on XML data , and so on , especially , it is further mature between XML and relation data transforming , but most of these theories only consider how to transform XML data into relational data , which only holds structure information , whereas not considering XML database schema from the point of designing database . Besides , although some research have advanced the Form of XML , the theory of definition is not consummate , which will bring much trouble on Web data processing later , and makes many redundant and inconsistent data.In this paper , we consider from the point of database designing and study further on constraints and storage of XML database , make direct normative processing on XML data , give the definition of redundancy and algorithm based on XML Key which can reduce the data redundancy and keep the consistency of XML data . The contributions of this paper are as follows:XML functional dependency , partial functional dependency and transitive functional dependency based on the symbol system of this paper are presented . We define logical implication and cover for XML functional dependency . Then we give a set of inference rules and a set of clear rules of XML function dependency which are sound . At last we give the correlative prove of rules;Referencing to the definition of XML multivalued dependency and a set of inference rules , we present the definition of MVD based on the symbol system of this paper; The XML key constrains is discussed based on the key concept in the relational database , and the definition of XML Main-Key and XML Deputy-Key are given in the form of aggregate . Based on the key , we discuss the data redundancy;Normalization rules and algorithm for XML documents are presented , based on the definition of Normal Forms for XML of different kinds of data redundancy;A new Normalized Translation Algorithm is propsed for translating XML schema to relational schema based on XML Key , which tackles the redundancy and un-standard expression in the translation . According to a group of deduce rules and clear rules about XML functional dependency, we take the XML Key as the center to divide the relation attributes, obtain the relation table . Besides we can guarantee the last relation schema more reasonable.