[sk5t]

Are you kidding, LDAP referrals as a model of how to do it? I mean, I did a lot of LDAP work back in the day, and that's not a feature that saw a lot of action outside academia. Just write your own thing on top of HTTP, that's got referrals too!

There are practically many ways of talking to database systems, if it isn't too troubling that some SQL is often happening somewhere. Like, there's Hasura, postgrest, etc.; or Mongo has a variety of drivers that support different inputs.

One might consider the most unix'y database to be Berkeley DB/Sleepycat, but that is probably not what you wanted. ;)