1. A computer system for staging data record changes from a faster storage medium to a slower storage medium using data query rewriting, the computer system comprising: a bus system; a storage device connected to the bus system, wherein the storage device stores computer readable program code; and a processor unit connected to the bus system, wherein the processor unit executes the computer readable program code to determine whether a data query corresponding to a particular data record is one of a transactional data query or an analytical data query in response to receiving the data query; rewrite the transactional data query to apply transactional delta changes to the particular data record on a storage-class memory of the computer system in response to determining that the data query is a transactional data query; and rewrite the analytical data query to select and reconcile each data record corresponding to the particular data record stored on the storage-class memory with the particular data record stored on a persistent data storage device of the computer system in response to determining that the data query is an analytical data query.