将行转换为JSON会导致错误

Question

我已经四处搜寻，但找不到能够将我指向正确方向的答案。

子查询单独运行时有效：

SELECT ROW_TO_JSON(rt)
FROM (
    SELECT EXTRACT(EPOCH FROM (events.addressed_on - events.processed_on))
    AS response_time
    FROM events
    WHERE events.addressed_on IS NOT NULL
) rt

返回：output

当我尝试将其包装在ROW_TO_JSON中时，出现以下错误：

由子查询返回的多于一行用作表达式

SELECT *,(
    SELECT ROW_TO_JSON(rt)
    FROM (
        SELECT EXTRACT(EPOCH FROM (events.addressed_on - events.processed_on))
        AS response_time
        FROM events
        WHERE events.addressed_on IS NOT NULL
    ) rt
) 
FROM events
WHERE events.addressed_on IS NOT NULL

我尝试使用json_agg，但它不会返回正确的数据，仅返回所有记录的第一个response_time。

想法/建议？