PostgreSQL 9.6:如何对嵌套的jsonb中的所有属性求和？

CREATE OR REPLACE FUNCTION jsonb_sum(jsonb_obj jsonb)
RETURNS numeric AS $$
DECLARE
    sum_value numeric := 0;
BEGIN
    IF jsonb_typeof(jsonb_obj) = 'object' THEN
        -- 遍历对象的所有属性
        FOR key IN SELECT jsonb_object_keys(jsonb_obj) LOOP
            sum_value := sum_value + jsonb_sum(jsonb_obj -> key);
        END LOOP;
    ELSIF jsonb_typeof(jsonb_obj) = 'array' THEN
        -- 遍历数组的所有元素
        FOR element IN SELECT jsonb_array_elements(jsonb_obj) LOOP
            sum_value := sum_value + jsonb_sum(element);
        END LOOP;
    ELSIF jsonb_typeof(jsonb_obj) = 'number' THEN
        -- 直接将数字类型的值累加到总和中
        sum_value := sum_value + jsonb_obj::numeric;
    END IF;

    RETURN sum_value;
END;
$$ LANGUAGE plpgsql;

SELECT jsonb_sum('{
    "a": 1,
    "b": {
        "c": 2,
        "d": {
            "e": 3,
            "f": [4, 5, 6]
        }
    }
}'::jsonb) AS total_sum;