Mysql INNER JOIN WHERE 耗时太长

Question

我的双重内部联接 sql 查询需要很长时间（>60 秒）。我在这里做错了什么吗？我该如何改进它？

SELECT coasters.coaster_name, coaster_models.model_id, models.model_name 
FROM coasters 
INNER JOIN coaster_models ON coasters.coaster_id = coaster_models.coaster_id 
INNER JOIN models ON coaster_models.model_id = models.model_id 
WHERE models.model_name = "SLC"

The Explain you asked me for

我刚刚做了这个声明，现在它显示了 8 个条目或更多条目，只是一个过山车。

SELECT coasters.coaster_name, manufacturers.manufacturer_name FROM coasters INNER JOIN coaster_models ON coasters.coaster_id = coaster_models.coaster_id INNER JOIN models ON coaster_models.model_id = models.model_id INNER JOIN manufacturers ON models.manufacturer_id = manufacturers.manufacturer_id WHERE manufacturers.manufacturer_name = "Vekoma"

输出：

Abyssus | Vekoma
Abyssus | Vekoma
Abyssus | Vekoma
Abyssus | Vekoma
Abyssus | Vekoma
Abyssus | Vekoma
Abyssus | Vekoma
Abyssus | Vekoma
Accelerator | Vekoma
Accelerator | Vekoma
Accelerator | Vekoma
Accelerator | Vekoma
Accelerator | Vekoma
Accelerator | Vekoma
Accelerator | Vekoma
Accelerator | Vekoma
etc...

Answer 1

确保您在

上有适当的复合（以及某种程度上的 rendendat）索引

table coaster  column coaster_id, coaster_name 
table coaster_models column coaster_id, model_id
table models model_name, model_id,

Mysql INNER JOIN WHERE 耗时太长

Mysql INNER JOIN WHERE takes too long

mysql

sql

select

inner-join