In defining database objects for storage in a storage hierarchy, frequencies of accesses of a plurality of database objects over a predetermined time period are observed. A mean and standard deviation for the plurality of database objects are computed based on the observed frequencies of accesses of the plurality of database objects. A z-score for a given database object is determined based on a comparison of the frequency of access for the given database with the mean and standard deviation computed for the plurality of database objects by the computing processor; and a level in the storage hierarchy corresponding to the z-score of the given database object is determined. The given database object may then be stored at the level in the storage hierarchy corresponding to the z-score of the given database object.