MySQL，查询 "NOT IN ( SELECT ... )"非常慢

Question

这是运行超过 10 分钟的查询。

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)

是否有替代查询运行得更快或有任何解决方案？非常感谢。

Answer 1

如果有适当的索引，您的查询应该可以正常工作。您也许可以尝试使用左连接。

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;

性能主要取决于索引。 对于性能，我建议使用以下索引:

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);