This isn't really true, in most cases you can write FDWs over foreign resources that let you query them like any other table, use them in joins, etc. Postgres

This isn't really true, in most cases you can write FDWs over foreign resources that let you query them like any other table, use them in joins, etc. Postgres is really more of an application platform than a database at this point. Just don't try to have the same PG instance be your master and your platform.