In designing a relational schema, we often consider that an attribute of a table is replicated into other table to reduce the join cost. And such a possible redundancy can be grasped by E/R model (i.e., semantic modeling). Similarly, in mapping XML into relations, we can consider some redundancy to enhance query performance and they can be grasped by the structural traits of DTD (or XML schema). In this paper, we introduce some such practical replication and a tool for efficient management of the replication. Finally, read and update query costs arising by employing the structural redundancy are analyzed experimentally and it is shown that these replication can be very useful.
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