[eru]

KV stores can be used to build relational databases in general.

Whether it's a good idea depends on your goal, and what alternative buildings blocks you have available.

(Eg if you are building your distributed relational database to run on top of lots of computers with spinning hard disks, you might want to expose some more characteristics of the hard disk directly to your database, so you can manage them; instead of trying to hide them behind an abstraction.)