Erlang already comes with a distributed DBMS called Mnesia https://erlang.org/doc/man/mnesia.html , which under the hood uses ETS/DETS depending on the configuration. In distributed Erlang projects you'll find that or abstractions over it. Mne sia makes the most sense in mu opinion when you only have 1-2 relations or just need some kind of distributed cache.

In Elixir apps you'll frequently find the aforementioned Ecto "ORM", which has adapters to different DBMSs like MySQL, PostgreSQL, and even Mnesia.