Overview of comparison of database environments

The comparison process enables you to perform the following tasks:

• Record changes made to a local or remote subsystem
• Understand structure changes between two subsystems to help determine changes to be migrated from one subsystem to the other
• Move application changes from one subsystem to another subsystem using the same application, without losing local modifications to the data structures
• Roll back changes made to a subsystem

The process of identifying structural differences between two copies of the same data structure, and then making the data structures identical, is referred to as synchronization. You might want to synchronize your data structures if, for example, you have separate development groups who independently modify several copies of a set of data structures. At various times, you need to synchronize the copies to ensure that all of the developers are using the same structure definitions.

When you perform a comparison so that you can change a version of a data structure, you compare baselines that represent the same set of structures at different points in time. This process is referred to as versioning. You might want to version your data structures so that you can properly maintain versions of your applications.

This section discusses how you can use Change Manager to compare your data structures. Using the Compare component of Change Manager to generate CDL enables you to automate the process of updating data structures. The benefit of using CDL rather than DDL is that CDL allows more types of modifications to data structures and can retain local modifications to those structures that would otherwise be lost.

The following figure illustrates the process of comparing your data structures using Change Manager.