This more sophisticated model encompasses a first level of operational databases, for instance, the one employed within marketing, production, and accounting processes, and a proper data warehouse environment. Within this solution, the databases are to be considered like feeding data sources, where the data is produced, possibly validated, and then made available to the data warehouse.

The data warehouse will then store and freeze data coming from databases, for instance, with a daily frequency.

Every set of data stored within a day will be labeled with a proper attribute showing the date of record. This will later allow us to retrieve records related to a specific time period in a sort of time machine functionality. Going back to our previous probability of default example, this kind of functionality will allow us to retrieve all default events that have occurred within a given time period, constituting the estimation sample for our model.

Two-level architecture is an optimal solution for data mining processes, since they will allow us to provide a safe environment, the previously mentioned data mart, to develop data mining activity, without compromising the quality of data residing within the remaining data warehouses and within the operational databases.