[geophile]

> If one of the purposes of relational databases is data modeling

Huh?

Creating a data model before creating a database, is like writing an outline before writing an essay. It organizes your thoughts and gives structure to what you are about to do. Once you have a data model, you can then implement it using whatever database technology you choose.

If you don't start with a data model, you literally don't know what you are doing.

[throwaway894345]

I think you misunderstood my comment. I’m arguing that relational databases would be more useful if they had sum-type semantics. Data models often have OR-shaped data, and pretending like this class of data doesn’t exist and making it the purview off application code makes relational databases much less useful than they might otherwise be.