An acquiring unit acquires from each of a plurality of database servers processing capacity information for a query received from a client. A generating unit generates a first code indicating a first processing and a second code indicating a second processing for the query. A first transmitting unit transmits the first code to the database servers. An executing unit executes the second processing by using first result data of XML data acquired by executing the first processing from the database servers. A second transmitting unit transmits second result data of XML data acquired by executing the second processing to the client.