Oracle Data Integrator is a powerful tool employing an Extract, Load, Transform (ELT) methodology for importing source data into your data warehouse.
In an ELT implementation data from all sources is loaded into the warehouse as part of the extract and load process. Only once the data is in the warehouse is it transformed to meet business requirements. By isolating the transformation process, future requirements can easily be incorporated into the warehouse structure.
Providing a development process that leads the developer through a consistent development path, enables future developers to deconstruct code more easily, thereby creating implementations that are easier to maintain.