Methods and apparatus for moving data objects in a database system. In one implementation, a database system includes: one or more data storage facilities for use in storing data composing records in tables of a database, where at least one data storage facility includes at least two types of data storage devices each belonging to a respective data storage class, and at least one data storage facility stores one or more data objects each including one or more migration parameters; one or more processing modules configured to manage the data stored in the data-storage facilities and to move data objects among data storage devices in different data storage classes according to the migration parameters of the data objects; and a database management component configured to coordinate the operation of the processing modules.