1. A database system comprising: a database comprising data having a particular physical representation; a data repository abstraction layer comprising logical fields corresponding to physical entities of the database; a query building interface allowing a user to build a query to access the database by specifying query conditions based on the logical fields; and a fallout manager configured to control the logical fields presented to the user by the query building interface based on usage characteristics of the logical fields in building queries, wherein the usage characteristics comprise an indication of at least one of: when a logical field was last used in building a query and a frequency with which the logical field has been used in building queries, wherein the fallout manager is configured to control the logical fields presented by the query building interface by hiding logical fields not used in building a query within a first predetermined period of time.