MySQL，使用「NOT IN（SELECT ...）」進行查詢的速度很慢

Question

查詢運行時間超過10分鐘。

SELECT * 
FROM tableA 
WHERE name NOT IN(
SELECT a.name 
FROM tableA a 
INNER JOIN tableB b ON a.code = b.code 
INNER JOIN tableC c ON c.number = b.number 
INNER JOIN tableD d ON d.code = b.code 
INNER JOIN tableE e ON e.content= d.content) 

是否有替代查詢運行更快或有任何解決方案？非常感謝。

Answer 1

儘量不要存在

SELECT * 
FROM tableA t1 
WHERE not exists (
SELECT 1 
from tableB b 
INNER JOIN tableC c ON c.number = b.number 
INNER JOIN tableD d ON d.code = b.code 
INNER JOIN tableE e ON e.content= d.content 
where t1.code = b.code 

) 

Answer 2

只要提供了適當的索引，您的查詢應該可以正常工作。你可以嘗試使用左連接。

select a.* 
from tableA a 
left join (
    select distinct a.name 
    from tableA a 
    inner join tableB b on a.code = b.code 
    inner join tableC c on c.number = b.number 
    inner join tableD d on d.code = b.code 
    inner join tableE e on e.content = d.content 
    ) b on a.name = b.name 
where b.name is null; 

性能將主要取決於指標。 出於性能考慮，我建議以下指標：

create index idx_tablea_code_name on tableA(code, name); 
create index idx_tableb_code_number on tableB(code, number); 
create index idx_tablec_number  on tableC(number); 
create index idx_tabled_code_content on tableD(code, content); 
create index idx_tablee_content  on tableE(content);