A method of constructing dynamic schema representing the structure of semistructured data

The structure of semistructured data is needed in order to query a large amount of semistructured data, although structure cannot be defined a priori. DataGuides and shape have been proposed to represent the structure of semistructured data. As these can behave as schema from the point of view of representing the structure of data, and are changed according to the existence of objects, these are called dynamic schema. The paper proposes a semi-dynamic construction method for the dynamic schema. The proposed method uses versions of the dynamic schema. Several versions are kept in the system. Each version of the dynamic schema keeps the objects required to construct the next version of it in a list. The correct dynamic schema can easily be constructed by using the versions of dynamic schema and the lists of objects. The performances in deriving the shape, and inserting and deleting objects are experimentally evaluated. Experimental results show that the proposed method is effective in the case where the retrieval occurs more frequently than the deletion.