METHOD FOR ESTIMATING A JOIN COST IN XQUERY QUERY BY A XQUERY QUERY JOIN COST ESTIMATOR

摘要

PURPOSE: A method for estimating a join cost in XQuery through an XQuery join cost estimator is provided to efficiently process a join operation included in the XQuery by estimating a join operation cost through estimated selectivity. CONSTITUTION: An XQuery written by a user is analyzed(201), and selectivity of each node which is joined is estimated(202). Join cost of each node pair is estimated through the selection value of estimated each node(203). The total join cost is estimated through the estimated join cost(204). The XQuery is written for distributed XML(eXtensible Displayup Language) views. The XML view comprises each node occurrence information and cardinality information.