It would be really useful if you could ignore some tables/indexes/foreign keys when exporting the diagram to SQL. This could be done with a simple tag such as [export: ignore] for example.
The use case is when you have an existing database, to which you want to design a new feature. This often requires interfacing with existing tables, which are implemented as stubs in dbml. However, these existing tables should not be created when exporting to sql.
To add to this - it would be nice to have an optional way to exclude comments from the export as well, they are useful in the diagram view, but i dont want them in my PostgreSQL (I am using an PostgreSQL-like program that does not support the comment command)