1. A method for synchronizing data between a first computer system and a second computer system, wherein the first computer system includes a data management system having data entities, the method comprising: configuring an integration data model to define a selected subset of the data entities of the data management system according to an expected amount of data change; creating a first database instance for the first computer system for the subset of the data entities selected responsive to the integration data model and a second database instance for the second computer system for the subset of the data entities selected responsive to the integration data model, wherein creating the first and second database instances includes configuring one of the database instances as a mirror of the other; creating respective time-based indicators in a change tracking repository responsive to performance of predefined operations on respective ones of the data entities in the selected subset; and synchronizing data of the subset of the data entities between the first computer system and the second computer system by communicating the data of the subset of the data entities between the first database instance and the second database instance and between the second database instance and the second system, wherein the second system feeds data to and receives data from the first system and wherein the synchronizing is responsive to the indicators in the change tracking repository.