这个问题在这里已经有答案了：

在postgresql中查找以秒为单位的时间戳之间的差异（3个答案）
10个月前关门了。
我有一张table：

CREATE TABLE trajectories_splitted
(
    user_id integer,
    session_id bigint NOT NULL,
    "timestamp" timestamp with time zone NOT NULL,
    lat double precision NOT NULL,
    lon double precision NOT NULL,
    alt double precision,

    PRIMARY KEY (session_id, "timestamp")
)

样本数据：

INSERT INTO trajectories_splitted (user_id, session_id,timestamp,lat,lon,alt)
VALUES   (1,20081023025304,'2008-10-23 02:53:04+01',39.984702,116.318417,492),
(1,20081023025304,'2008-10-23 02:53:10+01',39.984683,116.31845,492),
       (1,20081023025304,'2008-10-23 02:53:15+01',39.984686,116.318417,492),
       (1,20081023025304,'2008-10-23 02:53:20+01',39.984688,116.318385,492),
       (1,20081023025304,'2008-10-23 02:53:25+01',39.984655,116.318263,492),
       (1,20081023025304,'2008-10-23 02:53:30+01',39.984611,116.318026,493),
       (1,20081023025305,'2008-10-23 04:08:07+01',39.995777,116.286798,716),          
       (1,20081023025305,'2008-10-23 04:08:12+01',39.996832,116.285446,276 ),
       (1,20081023025305,'2008-10-23 04:08:42+01',39.984397,116.299292,931),
       (1,20081023025305,'2008-10-23 04:08:47+01',39.984426,116.299329,959),
       (1,20081023025305,'2008-10-23 04:08:52+01',39.984499,116.299413,983),
  (1,20081023025305,'2008-10-23 04:08:57+01',39.984424,116.299467,990),
       (1,20081023025305,'2008-10-23 04:09:02+01',39.98441,116.299477,940),
       (1,20081023025305,'2008-10-23 04:09:07+01',39.984421,116.299569,928),
       (1,20081023025305,'2008-10-23 04:09:12+01',39.984518,116.29953,902),
       (1,20081023025305,'2008-10-23 04:09:17+01',39.984488,116.299645,897)

获取行程总时间( session_id )因为列数据类型timestamp:

select session_id,
           (count(*)-1) / nullif((max(timestamp) - min(timestamp)), 0) as sampling_rate
    from trajectories_splitted
    group by session_id;
    ERROR:  operator does not exist: interval = integer
    LINE 2:        (count(*)-1) / nullif((max(timestamp) - min(timestamp...

                              ^
HINT:  No

 operator matches the given name and argument type(s). You might need to add explicit type casts.

然后：

select session_id,
       count(*) / nullif((max(timestamp) - min(timestamp))::int, 0) as sampling_rate
from trajectories_splitted
group by session_id;

ERROR:  cannot cast type interval to integer
LINE 2: ...ount(*) / nullif((max(timestamp) - min(timestamp))::int, 0) ...

这是db的小提琴