How to define the Postgres schema name in mods-available sql ?

In our postgres db we have a master_db and two underlying schemas, main and radius. How do I define the schema in /etc/freeradius/3.0/mods-available/sql ? server = "xxx" port = 5432 login = "" password = "" radius_db = "master_db" It seems I can only specify the database but not the underlying schema. Thanks,