如何优化这个mysql查询？

Question

我有这个疑问

SELECT id FROM btn 
WHERE parentid =0 
AND (mem_id =ANY(SELECT mem_id FROM network WHERE frd_id='401') || mem_id ='401') 
ORDER BY btn.date DESC LIMIT 0,20 

&此查询

SELECT mem_id FROM net WHERE frd_id='401' 

给我造成这样

mem_id 
34 
45 
633 
24 
22 

我希望优化其目前正在46秒后上述主查询扫描13,373条记录btn表

请问我可以优化这个查询吗？

thnks

Answer 1

SELECT DISTINCT b.id FROM btn b 
INNER JOIN network n ON (n.mem_id = b.mem_id) 
WHERE b.parentid = '0' 
AND ('401' IN (n.frd_id, n.mem_id)) 
ORDER BY b.date DESC 
LIMIT 20 OFFSET 0 

确保对

btn.mem_id, btn.parentid, btn.date 
network.mem_id, network.frd_id 

Answer 2

您将要索引您搜索的值。因此，基于上述两个：

parentid, frd_id, mem_id 

这应该大大帮助...