1. A computer-implemented method for monitoring transactions stored in a host data source comprising a plurality of source records and a plurality of source fields in each of the plurality of source records to determine lack of compliance of a transactional entity with one or more predetermined policies by maintaining an historical record of the transactional entity as changes are made to the entity, comprising the steps of: in a computer, identifying a subset of source fields of the plurality of source fields; in the computer, establishing an initial instance of a transactional entity in a monitoring database by extracting, from the subset of source fields in a first source record, a first selected subset of information relating to the transactional entity from the host data source storing data associated with the transactional entity; in the computer, storing the subset of information and version information in the monitoring database as a monitoring entity; in the computer, in response to a determination of a change to data associated with the transactional entity, establishing a subsequent instance of the transactional entity in the monitoring database by extracting, from the subset of source fields in the first source record, a second selected subset of information relating to the transactional entity from the host data source; in the computer, storing the second subset of information and version information in the monitoring database as a second monitoring entity; in the computer, applying predetermined policy rules to the monitoring entities in the monitoring database to determine lack of compliance of the initial and subsequent instances of the transactional entity with one or more predetermined policies that make reference to different versions of a particular transactional entity.