MySQL 查询连接花费的时间太长

Question

我有一个足够简单的查询，运行时间几乎为 4 分钟。

关于表格:

表 A 有 25 列和 18354 行表 B 有 24 列和 97889 行

查询:

select (sum(a.a)/sum(a.ab)) as ab_avg,
sum(a.h) as h_sum,
((sum(a.2B) + sum(a.3B) + sum(a.4B))/sum(a.ab)) as b_avg,
(sum(a.sb) / (sum(a.sb) + sum(a.cs))) as sb_pct,
(sum(a.ab) / (sum(a.hr)) as ab_hr_ratio,
(sum(a.ab) / sum(a.so)) as ab_so_ratio,
b.lastname,
b.firstname
from a, b
where b.id = a.id
group by b.year

MySQL 准确地返回了它应该返回的内容，但我想这个查询不应该花费 4 分钟来运行。我是否做错了什么导致了性能问题？

Answer 1

我向年份和 ID 添加了索引，它在 0.45 秒内运行。谢谢!