我怎樣才能加速這一MySQL查詢（計數明顯與加盟）

Question

你有什麼想法，我怎麼能加快下面的查詢？

select count(distinct t1.var1) 
from table_a t1 
join table_b t2 on t1.var2 = t2.var1 
    and t2.date between '2016-11-05 00:00:00' and '2016-11-10 23:59:59' 
    and t2.var3 = 3; 

我已經試過這樣：

select count(*) 
from (select distinct t1.var1 from table_a t1 
join table_b t2 on t1.var2 = t2.var1 
    and t2.date between ('2016-11-05 00:00:00') and ('2016-11-10 23:59:59') 
    and t2.var3 = 3) as temp 

，但它並不比前一個

Answer 1

select count(distinct(t1.var1)) 
from table_a t1 
join (select * from table_b where date between ('2016-11-05 00:00:00') and ('2016-11-10 23:59:59') and var3 = 3) t2 
on t1.var2 = t2.var1; 

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