In a structure where a table is partitioned into multiple databases according to a certain partitioning method, a coordinator server changes allocation information that is used to determine a database into which each of data records should be registered when an allocation change command is issued. The coordinator server stores therein allocation history information, which is the allocation information used before the change. When an entry request to make an entry of a new data record from a client, a database to enter the new data record is determined based on the stored allocation history information and the changed allocation information, and an entry request is sent to a database server having the determined database.