Synchronization of databases with record sanitizing and intelligent comparison

A method of synchronizing at least a first and a second database each containing dated records such as events, wherein the records of the first and second databases are synchronized across a narrow date range narrower than the date range of the records of at least one of the databases. A prior synchronization can be performed across a prior date range. The date range of the prior synchronization is stored, along with the history file containing information representative of the content of the databases following the prior synchronization. When a current synchronization is performed, it is performed across a date range that combines the prior date range with the current date range.