Database server, database management method, and storage medium

A database server includes a database manager and a synchronization processing unit. When the database server is in a first state in which the database server receives requests from a client, the database manager updates a database in accordance with a request from the client and registers both update data for causing another database server included in the plurality of database servers to update a database of the other database server and management information of the update data for each data management unit in a memory on the basis of the request. When the database server is in the first state, the synchronization processing unit transmits the update data registered in the memory to the other database.