Schema Evolution

Schema Evolution

The storage definition for a class is generated when the class is first compiled. When you compile a persistent (or serial) class that uses the default %Storage.Persistent storage class, the class compiler analyzes the properties defined by the class and automatically uses them in the storage definition.

Similarly, when you add properties, the class compiler updates the storage definition to provide access to these properties. When you remove properties, their descriptions within the storage definition remain unchanged.

This automatic process is schema evolution, and the goal is to safely preserve access to your data. Schema evolution does not apply to classes that use %Storage.SQL.