Upgrading and Extending Daml applications

Database schemas tend to evolve over time. A new feature in your application might need an additional choice in one of your templates. Or a change in your data model will make you application perform better. We distinguish two kinds of changes to a Daml model:

• A Daml model extension
• A Daml model upgrade

An extension adds new templates and data structures to your model, while leaving all previously written definitions unchanged.

An upgrade changes previously defined data structures and templates.

Whether extension or upgrade, your new code needs to be compatible with data that is already live in a production system. The next two sections show how to extend and upgrade Daml models. The last section shows how to automate the data migration process.