A method for storing XML documents in a relational database system while exploiting XML Schema information to capture information about types, inheritance, equivalence classes, and integrity constraints in the generated relational schema, enabling efficient querying. The invention simplifies complex XML schema types, translates the simplified XML schema types into relational tables, and then stores relations corresponding to each XML element in relational table rows. The simplification includes grouping all occurrences of a given element together, assembling two or more element types into element groups if the schema indicates that elements of those element types will occur the same number of times, and applying a number of transformation rules to the element groups. The translation includes constructing a type graph from the simplified schema, building an element graph for each global element in the simplified schema from the type graph, and generating relational tables from the element graph.
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