create or replace function etl_utils.get_referrer_key(_referrer_source_type text, _referrer_source_name text)
  returns bigint
  STABLE
as
$$
DECLARE
 _referrer_key bigint;
BEGIN
  if _referrer_source_type is null and _referrer_source_name is null then
    return -1;
  end if;
  
  select referrer_key
   into _referrer_key
  from t_referrer_dim
  where referrer_source_type = _referrer_source_type
        and referrer_source_name = _referrer_source_name;
    
  return _referrer_key;
END;
$$ language plpgsql;

create or replace function etl_utils.get_referrer_key(_referrer_source_type text, _referrer_source_name text)
  returns bigint
  STABLE
as
$$
select coalesce(
                 (
                  select referrer_key
                    from t_referrer_dim
                  where referrer_source_type = _referrer_source_type
                            and referrer_source_name = _referrer_source_name
                 ),
                 -1
                )

$$ language sql