Mysql SQL性能问题：查找路由

我正在努力解决SQL查询的性能问题

我坐火车旅行了5个站，名字是a-B-C-D-E。 一位乘客预订了一张B-C-D车票。 我需要找回我的乘客去的所有车站

我所储存的：

JOURNEY
+----+--------------------+-------------------+-------------------+-----------------+
| id | departure_datetime | arrival_datetime  | departure_station | arrival_station |
+----+--------------------+-------------------+-------------------+-----------------+
|  1 | 2018-01-01 06:00   | 2018-01-01 10:00  | A                 | E               |
+----+--------------------+-------------------+-------------------+-----------------+

BOOKING
+----+------------+-------------------+-----------------+
| id | journey_id | departure_station | arrival_station |
+----+------------+-------------------+-----------------+
|  1 |          1 | B                 | D               |
+----+------------+-------------------+-----------------+

LEG
+----+------------+-------------------+-----------------+------------------+------------------+
| id | journey_id | departure_station | arrival_station |  departure_time  |   arrival_time   |
+----+------------+-------------------+-----------------+------------------+------------------+
|  1 |          1 | A                 | B               | 2018-01-01 06:00 | 2018-01-01 07:00 |
|  2 |          1 | B                 | C               | 2018-01-01 07:00 | 2018-01-01 08:00 |
|  3 |          1 | C                 | D               | 2018-01-01 08:00 | 2018-01-01 09:00 |
|  4 |          1 | D                 | E               | 2018-01-01 09:00 | 2018-01-01 10:00 |
+----+------------+-------------------+-----------------+------------------+------------------+

我发现检索站点的唯一方法是：

select b.id as booking, l.departure_station, l.arrival_station
from JOURNEY j
inner join BOOKING b on j.id = b.journey_id
inner join LEG dl on (j.id = dl.journey_id and b.departure_station = dl.departure_station)
inner join LEG al on (j.id = al.journey_id and b.arrival_station = al.arrival_station)
inner join LEG l on (j.id = l.journey_id and l.departure_time >= dl.departure_time and l.arrival_time <= al.arrival_time)
where b.id = 1

我在mariadb 12.2上工作，所以我可以访问窗口功能，但我仍然对它不太满意

谢谢

编辑：创建表：

CREATE TABLE `BOOKING` (
    `id` INT(11) NOT NULL,
    `journey_id` INT(11) NULL DEFAULT NULL,
    `departure_station` VARCHAR(50) NULL DEFAULT NULL,
    `arrival_station` VARCHAR(50) NULL DEFAULT NULL,
    PRIMARY KEY (`id`)
);

CREATE TABLE `JOURNEY` (
    `id` INT(11) NOT NULL AUTO_INCREMENT,
    `departure_time` DATETIME NULL DEFAULT NULL,
    `arrival_time` DATETIME NULL DEFAULT NULL,
    `departure_station` VARCHAR(50) NULL DEFAULT NULL,
    `arrival_station` VARCHAR(50) NULL DEFAULT NULL,
    PRIMARY KEY (`id`)
);

CREATE TABLE `LEG` (
    `id` INT(11) NOT NULL,
    `journey_id` INT(11) NULL DEFAULT NULL,
    `departure_station` VARCHAR(50) NULL DEFAULT NULL,
    `arrival_station` VARCHAR(50) NULL DEFAULT NULL,
    `departure_time` DATETIME NULL DEFAULT NULL,
    `arrival_time` DATETIME NULL DEFAULT NULL,
    PRIMARY KEY (`id`)
);

尝试使用left join并使用REGEXP来登记出发站和到达站

select T3.id booking_id , T1.departure_station,T1.arrival_station
from LEG T1
left join JOURNEY T2 on T1.`journey_id` = T2.`id`
  and (T1.`departure_time` >= T2.`departure_datetime` and T1.`arrival_time` <= T2.`arrival_datetime`)
left join BOOKING T3 on  T3.`id` = T2.`id` 
    and T1.departure_station REGEXP (CONCAT('[',T3.departure_station , '-' , T3.arrival_station,']' ))
    and T1.arrival_station REGEXP (CONCAT('[',T3.departure_station , '-' , T3.arrival_station,']' ))
where T1.journey_id = 1 and T3.id is not null ;

测试DDL：

---

我不喜欢你的数据库模式。 但在您的特殊情况下，因为您的查询对您有好处。 我只需要创建几个索引来加快执行速度。 一般来说，当您需要将表连接到自身几次时，并没有什么问题

尝试只添加4个索引：

CREATE INDEX journey ON BOOKING (journey_id);
CREATE INDEX arrival ON LEG (journey_id, arrival_station);
CREATE INDEX departure ON LEG (journey_id, departure_station);
CREATE INDEX d_a_time ON LEG (journey_id, departure_time, arrival_time);

再次运行查询，使用索引时应该会快得多。

我建议使用：

---

您给出的示例的预期结果是什么？我在问题中添加了，很抱歉遗漏了…请为每个表提供您的创建表请回答问题请检查我的答案。创建您需要的索引。为什么您认为这样更快？@Alex Asker加入三次Leg抱歉，我没有指定站点名称，但站点名称不是按字母顺序排列的，可以是任何名称。另一方面，出发时间总是与上次到达时间相同。你的回答给了我一些想法，谢谢。这是我数据库模式的一个非常轻量级的模型。实际上，LEG、travel和BOOKING中的站点只是指向站点表的外键id。谢谢你的回答，我会尝试使用那些特定的ID。我的答案不是关于ID，而是关于索引。谢谢你那些在出发和到达时丢失的索引，现在好多了。酷，我喜欢这个建议。我明天肯定会尝试，谢谢。注意：需要MySQL 8或更高版本我们在查询结束时还需要b.id=1吗？我觉得我们在CTE时就已经做到了。最后看看这种方法，我真的怀疑它是否会带来任何性能改进。对我来说，它使事情变得更慢，因为您使用类似于leg_cte的视图或临时表，而不是基本的核心表leg，这对于Mysql或MariaDB 10.2来说要好得多。

| booking_id | departure_station | arrival_station |
|------------|-------------------|-----------------|
|          1 |                 B |               C |
|          1 |                 C |               D |

CREATE TABLE JOURNEY
    (`id` int, `departure_datetime` datetime, `arrival_datetime` datetime, `departure_station` varchar(1), `arrival_station` varchar(1))
;

INSERT INTO JOURNEY
    (`id`, `departure_datetime`, `arrival_datetime`, `departure_station`, `arrival_station`)
VALUES
    (1, '2018-01-01 06:00:00', '2018-01-01 10:00:00', 'A', 'E')
;


CREATE TABLE BOOKING
    (`id` int, `journey_id` int, `departure_station` varchar(1), `arrival_station` varchar(1))
;

INSERT INTO BOOKING
    (`id`, `journey_id`, `departure_station`, `arrival_station`)
VALUES
    (1, 1, 'B', 'D')
;


CREATE TABLE LEG
    (`id` int, `journey_id` int, `departure_station` varchar(1), `arrival_station` varchar(1), `departure_time` datetime, `arrival_time` datetime)
;

INSERT INTO LEG
    (`id`, `journey_id`, `departure_station`, `arrival_station`, `departure_time`, `arrival_time`)
VALUES
    (1, 1, 'A', 'B', '2018-01-01 06:00:00', '2018-01-01 07:00:00'),
    (2, 1, 'B', 'C', '2018-01-01 07:00:00', '2018-01-01 08:00:00'),
    (3, 1, 'C', 'D', '2018-01-01 08:00:00', '2018-01-01 09:00:00'),
    (4, 1, 'D', 'E', '2018-01-01 09:00:00', '2018-01-01 10:00:00')
;

CREATE INDEX journey ON BOOKING (journey_id);
CREATE INDEX arrival ON LEG (journey_id, arrival_station);
CREATE INDEX departure ON LEG (journey_id, departure_station);
CREATE INDEX d_a_time ON LEG (journey_id, departure_time, arrival_time);

WITH leg_cte as
(
    SELECT l.* FROM leg l
        JOIN booking b
            ON l.journey_id = b.journey_id
    WHERE b.id = 1
)

SELECT
    b.id as booking, 
    l.departure_station, 
    l.arrival_station
FROM
    booking b
    JOIN leg_cte dl
        ON b.departure_station = dl.departure_station
    JOIN leg_cte al 
        ON b.arrival_station = al.arrival_station
    JOIN leg_cte l 
        ON l.departure_time >= dl.departure_time AND l.arrival_time <= al.arrival_time

WHERE b.id = 1