优化同一张表的多个子查询

Question

我有一个查询，其中同一个表上有多个子查询。 我尝试将它们转换为左连接，但这比此查询花费的时间更多。

有问题的表是：product_class_link

如果有人可以帮助我解决任何问题，那就太好了。

提前致谢

select pc.id as id,
       pc.code,
       pc.name,
       pc.deliver_from,
       pc.delivery,
       pc.is_active,
       1 as results,
       cr.ship_date_advance, 
       p.callouts, 
       p.coid,
       p.c_name, 
       pc.start_expire_date, 
       pc.end_expire_date
from product_collection pc
join (select p.product_collection_id, 
             pdc.id as coid, pdc.name as c_name,
             count(distinct pcl.product_id) as callouts, pi.quantity
      from product p
      join product_color pclr on pclr.product_id=p.id 
      join product_collection pc on pc.id=p.product_collection_id and pc.client_id = 142 and pc.active='True'
      left join product_gender_link pgl on pgl.product_id=p.id
      left join product_callout_link pcl on pcl.product_collection_id=pc.id and pcl.product_id=p.id
      left join product_callout pdc on pdc.id=pcl.product_callout_id and pdc.client_id=142
      left join product_inventory pi on pi.product_color_id=pclr.id and pi.quantity>0 
      left join product_price_link ppl on ppl.product_id=p.id
      LEFT JOIN product_class_link pdcl ON pdcl.product_id = p.id
      where ppl.product_price_id in (447,249,456) 
      and p.active = 'True'
      and pgl.product_gender_id = 411
      AND ( ( product_sub_class_id = 10 AND pdcl.product_id IN ( select DISTINCT product_id 
                                                                 FROM product_class_link 
                                                                 WHERE  product_sub_class_id = 51 
                                                                 OR  product_sub_class_id = 53 
                                                                 OR  product_sub_class_id = 55 
                                                                 ) 
            )  
            OR  ( product_sub_class_id = 11 AND pdcl.product_id IN (select DISTINCT product_id FROM product_class_link WHERE  product_sub_class_id = 51 OR  product_sub_class_id = 55 )  )  
            OR  ( product_sub_class_id = 12 AND pdcl.product_id IN (select DISTINCT product_id FROM product_class_link WHERE  product_sub_class_id = 51 OR  product_sub_class_id = 53 OR  product_sub_class_id = 55 )  )  
            OR  ( product_sub_class_id = 14 AND pdcl.product_id IN (select DISTINCT product_id FROM product_class_link WHERE  product_sub_class_id = 51 OR  product_sub_class_id = 52 OR  product_sub_class_id = 55 )  )  
            OR  ( product_sub_class_id = 13 AND pdcl.product_id IN (select DISTINCT product_id FROM product_class_link WHERE  product_sub_class_id = 51 ))  
            OR  ( product_sub_class_id = 15 AND pdcl.product_id IN (select DISTINCT product_id FROM product_class_link WHERE  product_sub_class_id = 51 OR  product_sub_class_id = 52 OR  product_sub_class_id = 55 )  )  
            OR  ( product_sub_class_id = 24 AND pdcl.product_id IN (select DISTINCT product_id FROM product_class_link WHERE  product_sub_class_id = 51 )  )  
            OR  ( product_sub_class_id = 29 AND pdcl.product_id IN (select DISTINCT product_id FROM product_class_link WHERE  product_sub_class_id = 51 )  )  
            OR  ( product_sub_class_id = 25 AND pdcl.product_id IN (select DISTINCT product_id FROM product_class_link WHERE  product_sub_class_id = 51 )  )  
            OR  ( product_sub_class_id = 30 AND pdcl.product_id IN (select DISTINCT product_id FROM product_class_link WHERE  product_sub_class_id = 51 )  )  
            OR  ( product_sub_class_id = 20 AND pdcl.product_id IN (select DISTINCT product_id FROM product_class_link WHERE  product_sub_class_id = 51 )  )  
            OR  ( product_sub_class_id = 23 AND pdcl.product_id IN (select DISTINCT product_id FROM product_class_link WHERE  product_sub_class_id = 51 )  )  
            )
        and (pc.is_active < 2 or pi.quantity IS NOT NULL)
        group by pc.id, pdc.id
      ) as p on p.product_collection_id=pc.id
left join client_shipdate_rules cr on cr.product_collection_id=pc.id
where  pc.active='True'
and pc.client_id = 142
group by pc.id, p.coid
order by pc.position,pc.name, pc.deliver_from, p.coid

这是解释查询的 output：

1   PRIMARY pc  
    NULL
    ref PRIMARY,product_collection_client,active    active  1   const   32  100.00  Using where; Using temporary; Using filesort    
1   PRIMARY cr  
    NULL
    eq_ref  PRIMARY PRIMARY 4   db148189_atonce_1_4.pc.id   1   100.00  
    NULL
    
1   PRIMARY <derived2>  
    NULL
    ref <auto_key0> <auto_key0> 4   db148189_atonce_1_4.pc.id   106 100.00  
    NULL
    
2   DERIVED pgl 
    NULL
    ref PRIMARY,product_id,product_gender_id    product_gender_id   2   const   1704864 100.00  Using where; Using index; Using temporary; Using filesort   
2   DERIVED p   
    NULL
    eq_ref  PRIMARY,product_collection,active   PRIMARY 4   db148189_atonce_1_4.pgl.product_id  1   50.00   Using where 
2   DERIVED pc  
    NULL
    eq_ref  PRIMARY,product_collection_client,is_active,active  PRIMARY 4   db148189_atonce_1_4.p.product_collection_id 1   6.75    Using where 
2   DERIVED pclr    
    NULL
    ref product_color_ui01,product_code_unique,product_color_product    product_color_product   4   db148189_atonce_1_4.pgl.product_id  1   100.00  Using index 
2   DERIVED pcl 
    NULL
    ref product_collection_id,product_id    product_id  8   db148189_atonce_1_4.pgl.product_id,db148189_atonce_1_4.p.product_collection_id  1   100.00  Using index 
2   DERIVED pdc 
    NULL
    eq_ref  PRIMARY PRIMARY 4   db148189_atonce_1_4.pcl.product_callout_id  1   100.00  Using where 
2   DERIVED pi  
    NULL
    ref product_color_id,qUANITY_PRODUCT_COLOR_ID   product_color_id    4   db148189_atonce_1_4.pclr.id 2   17.30   Using where 
2   DERIVED ppl 
    NULL
    ref PRIMARY,product_id  product_id  4   db148189_atonce_1_4.pgl.product_id  3   30.00   Using where; Using index    
2   DERIVED pdcl    
    NULL
    ref product_id_2,product_sub_class_id,product_id    product_id_2    5   db148189_atonce_1_4.pgl.product_id  2   68.53   Using where; Using index    
14  DEPENDENT SUBQUERY  product_class_link  
    NULL
    index_subquery  product_id_2,product_sub_class_id,product_id    product_id_2    10  func,const  1   100.00  Using where; Using index    
13  DEPENDENT SUBQUERY  product_class_link  
    NULL
    index_subquery  product_id_2,product_sub_class_id,product_id    product_id_2    10  func,const  1   100.00  Using where; Using index    
12  DEPENDENT SUBQUERY  product_class_link  
    NULL
    index_subquery  product_id_2,product_sub_class_id,product_id    product_id_2    10  func,const  1   100.00  Using where; Using index    
11  DEPENDENT SUBQUERY  product_class_link  
    NULL
    index_subquery  product_id_2,product_sub_class_id,product_id    product_id_2    10  func,const  1   100.00  Using where; Using index    
10  DEPENDENT SUBQUERY  product_class_link  
    NULL
    index_subquery  product_id_2,product_sub_class_id,product_id    product_id_2    10  func,const  1   100.00  Using where; Using index    
9   DEPENDENT SUBQUERY  product_class_link  
    NULL
    index_subquery  product_id_2,product_sub_class_id,product_id    product_id_2    10  func,const  1   100.00  Using where; Using index    
8   DEPENDENT SUBQUERY  product_class_link  
    NULL
    index_subquery  product_id_2,product_sub_class_id,product_id    product_id_2    5   func    2   9.52    Using where; Using index    
7   DEPENDENT SUBQUERY  product_class_link  
    NULL
    index_subquery  product_id_2,product_sub_class_id,product_id    product_id_2    10  func,const  1   100.00  Using where; Using index    
6   DEPENDENT SUBQUERY  product_class_link  
    NULL
    index_subquery  product_id_2,product_sub_class_id,product_id    product_id_2    5   func    2   9.52    Using where; Using index    
5   DEPENDENT SUBQUERY  product_class_link  
    NULL
    index_subquery  product_id_2,product_sub_class_id,product_id    product_id_2    5   func    2   9.85    Using where; Using index    
4   DEPENDENT SUBQUERY  product_class_link  
    NULL
    index_subquery  product_id_2,product_sub_class_id,product_id    product_id_2    5   func    2   9.51    Using where; Using index    
3   DEPENDENT SUBQUERY  product_class_link  
    NULL
    index_subquery  product_id_2,product_sub_class_id,product_id    product_id_2    5   func    2   9.85    Using where; Using index    

Answer 1

OR难以优化； 看看你能不能避免它。

IN ( SELECT... ) is usually bad for performance. It can sometimes be turned into a IN ( SELECT... ) is usually bad for performance. It can sometimes be turned into a JOIN or EXISTS(SELECT...) . This is especially valid since you have . This is especially valid since you have DISTINCT`。

看看您是否可以将其从WHERE移出并移入JOIN ：

   SELECT  DISTINCT product_id
                FROM  product_class_link
                WHERE  product_sub_class_id = 51 )

其中一些索引可能会有所帮助：

PC:   INDEX(active, client_id, id)
cr:   INDEX(product_collection_id,  ship_date_advance)
pcl:  INDEX(product_collection_id,  product_id, product_callout_id)
pi:   INDEX(quantity, product_color_id)
pclr: INDEX(product_id,  id)
PC:   INDEX(is_active, id,  client_id, active)
pgl:  INDEX(product_gender_id, product_id)
ppl:  INDEX(product_price_id, product_id)
pdcl: INDEX(product_id)

警告：由于一些别名用于多个表，以上可能是“错误的”。 （例如p ）

product_sub_class_id在哪个表中？

如果您不需要LEFT ，请不要说出来。