If an open source database-backed web application uses the AGPL-3.0 license, do its viral aspects extend to the database schema? If another app, written in a different programming language, uses the same schema, must it also be AGPL-3.0?
The intent behind the AGPL is that users of a web-service get the freedom and the means to recreate a web-service with the same functionality. To be able to do this, the (relevant portions of the) database schema must also be available under an open-source license.
However, the license of the database schema does not have to be the AGPL license. It is sufficient if the database schema is licensed under a license that is compatible with the AGPL. This means that another application can use the same database schema without being bound by the AGPL.
Also, the original author of the database schema is not bound by any particular license and can freely use the same database schema both in an AGPL application and a non-free application.