1. A database migration data processing system configured for pre-migration performance prediction of a target database management system (DBMS), the system comprising: source and target servers communicatively coupled to one another over a computer communications network, the servers individually comprising memory and at least one processor; a source DBMS executing in the source server, and a target DBMS executing in the target server; a subject database managed by the source DBMS; and, a predictive performance module coupled to each of the source DBMS and target DBMS, the module comprising program code enabled to execute a calibration workload in the target DBMS to produce a conversion factor of cost of executing the calibration workload to temporal performance of executing the calibration workload, to subsequently submit a sample workload from the database of the source DBMS for evaluation of cost of execution on an empty replica of the database in the target DBMS and to predict a temporal performance of the sample workload in the target DBMS as a product of the conversion factor and the cost of execution of the sample workload on the empty replica of the database in the target DBMS.