使用group by和sum优化查询

Question

以下查询执行8秒

SELECT `currency`, sum(amount) as amount
FROM `p_transactions`
WHERE `member_id` = 2051
AND `transaction_type` = 'debit'
AND `transaction_status` = 12
GROUP BY `currency`

但如果删除GROUP BY currency部分它会短至2秒。有没有办法加快这个查询？

索引是复合的（member_id，transaction_type，transaction_status）。

Answer 1

尝试将索引更改为：

(member_id, transaction_type, transaction_status, currency)