2

我的这个查询运行了 3 分钟以上。我希望优化以在几秒钟内运行：

SELECT Count(DISTINCT l.licitatii_id) c 
FROM   licitatii_ue l 
       INNER JOIN domenii_licitatii dl 
               ON l.licitatii_id = dl.licitatii_id 
                  AND dl.tip_licitatie = '2' 
       INNER JOIN domenii d 
               ON dl.domenii_id = d.domenii_id 
                  AND d.tip_domeniu = '1' 
                  AND d.status = 1 
WHERE  l.status = 1 
       AND l.data_limita >= '1357768800'

解释显示：

*** row 1 ***
          table:  d
           type:  ref
  possible_keys:  PRIMARY,key_status_tip_domeniu,ind_v1
            key:  key_status_tip_domeniu
        key_len:  9
            ref:  const,const
           rows:  39
          Extra:  Using where; Using index
*** row 2 ***
          table:  dl
           type:  ref
  possible_keys:  PRIMARY,licitatii_id,licitatii_id_2
            key:  PRIMARY
        key_len:  5
            ref:  web1db1.d.domenii_id,const
           rows:  1882
          Extra:  Using index
*** row 3 ***
          table:  l
           type:  eq_ref
  possible_keys:  PRIMARY,data_limita
            key:  PRIMARY
        key_len:  4
            ref:  web1db1.dl.licitatii_id
           rows:  1
          Extra:  Using where

架构：

合法性

  PRIMARY KEY (`licitatii_id`),
  UNIQUE KEY `nr_ue` (`nr_ue`),
  KEY `nume` (`nume`),
  KEY `tip_licitatie` (`tip_licitatie`),
  KEY `surse_ue_id` (`surse_ue_id`),
  KEY `data_publicarii` (`data_publicarii`),
  KEY `tara_id` (`tara_id`),
  KEY `creat` (`creat`),
  KEY `data_limita` (`data_limita`),
  FULLTEXT KEY `nume_fulltext` (`nume`,`descriere`)
) ENGINE=MyISAM

/*Index Information*/
---------------------

Table         Non_unique  Key_name         Seq_in_index  Column_name      Collation  Cardinality  Sub_part  Packed  Null    Index_type  Comment  
------------  ----------  ---------------  ------------  ---------------  ---------  -----------  --------  ------  ------  ----------  ---------
licitatii_ue           0  PRIMARY                     1  licitatii_id     A               136456    (NULL)  (NULL)          BTREE                
licitatii_ue           0  nr_ue                       1  nr_ue            A               (NULL)    (NULL)  (NULL)  YES     BTREE                
licitatii_ue           1  nume                        1  nume             A                68228    (NULL)  (NULL)          BTREE                
licitatii_ue           1  tip_licitatie               1  tip_licitatie    A                   13    (NULL)  (NULL)  YES     BTREE                
licitatii_ue           1  surse_ue_id                 1  surse_ue_id      A                    1    (NULL)  (NULL)          BTREE                
licitatii_ue           1  data_publicarii             1  data_publicarii  A               136456    (NULL)  (NULL)  YES     BTREE                
licitatii_ue           1  tara_id                     1  tara_id          A                   41    (NULL)  (NULL)  YES     BTREE                
licitatii_ue           1  creat                       1  creat            A               136456    (NULL)  (NULL)  YES     BTREE                
licitatii_ue           1  data_limita                 1  data_limita      A                  770    (NULL)  (NULL)  YES     BTREE                
licitatii_ue           1  nume_fulltext               1  nume             (NULL)               1    (NULL)  (NULL)          FULLTEXT             
licitatii_ue           1  nume_fulltext               2  descriere        (NULL)               1    (NULL)  (NULL)  YES     FULLTEXT

domenii_licitatii

  PRIMARY KEY (`domenii_id`,`tip_licitatie`,`licitatii_id`),
  KEY `licitatii_id` (`licitatii_id`,`tip_licitatie`),
  KEY `licitatii_id_2` (`licitatii_id`)
) ENGINE=InnoDB 

/*Index Information*/
---------------------

Table              Non_unique  Key_name        Seq_in_index  Column_name    Collation  Cardinality  Sub_part  Packed  Null    Index_type  Comment  
-----------------  ----------  --------------  ------------  -------------  ---------  -----------  --------  ------  ------  ----------  ---------
domenii_licitatii           0  PRIMARY                    1  domenii_id     A                   20    (NULL)  (NULL)          BTREE                
domenii_licitatii           0  PRIMARY                    2  tip_licitatie  A                  228    (NULL)  (NULL)          BTREE                
domenii_licitatii           0  PRIMARY                    3  licitatii_id   A               430634    (NULL)  (NULL)          BTREE                
domenii_licitatii           1  licitatii_id               1  licitatii_id   A               430634    (NULL)  (NULL)          BTREE                
domenii_licitatii           1  licitatii_id               2  tip_licitatie  A               430634    (NULL)  (NULL)          BTREE                
domenii_licitatii           1  licitatii_id_2             1  licitatii_id   A               430634    (NULL)  (NULL)          BTREE

多梅尼

  PRIMARY KEY (`domenii_id`),
  KEY `key_status_tip_domeniu` (`status`,`tip_domeniu`),
  KEY `ind_v1` (`domenii_id`,`tip_domeniu`,`status`),
  KEY `parent_id` (`parent_id`)
) ENGINE=InnoDB 

/*Index Information*/
---------------------

Table    Non_unique  Key_name                Seq_in_index  Column_name  Collation  Cardinality  Sub_part  Packed  Null    Index_type  Comment  
-------  ----------  ----------------------  ------------  -----------  ---------  -----------  --------  ------  ------  ----------  ---------
domenii           0  PRIMARY                            1  domenii_id   A                   79    (NULL)  (NULL)          BTREE                
domenii           1  key_status_tip_domeniu             1  status       A                    4    (NULL)  (NULL)  YES     BTREE                
domenii           1  key_status_tip_domeniu             2  tip_domeniu  A                   11    (NULL)  (NULL)          BTREE                
domenii           1  ind_v1                             1  domenii_id   A                   79    (NULL)  (NULL)          BTREE                
domenii           1  ind_v1                             2  tip_domeniu  A                   79    (NULL)  (NULL)          BTREE                
domenii           1  ind_v1                             3  status       A                   79    (NULL)  (NULL)  YES     BTREE                
domenii           1  parent_id                          1  parent_id    A                   79    (NULL)  (NULL)          BTREE
4

2 回答 2

1

您确实需要表上的复合索引。

table             index
licitatii         ( status, data_limita, licitatii_id )
domenii_licitatii ( licitatii_id, tip_licitatie )
domenii           ( domenii_id, tip_domeniu, status )

您应该拥有有助于优化联接和 where 条件的复合键。此外，正如我所包含的，查询引擎可以直接从索引中找到连接的值，而不是返回到实际数据的页面。如果索引中只有一列，则查询将转到原始数据进行连接。看看它对你有什么作用。

好的，是的，其他两个索引和您添加的第三个索引 - 没有帮助。然后我会尝试反转查询......不完全了解数据，但看起来它们是某种类型的查找类别元素。尝试

select STRAIGHT_JOIN
      Count(DISTINCT dl.licitatii_id) c
   from
      domenii d
         join domenii_licitatii dl
            on d.domenii_id = dl.domenii_id
           AND dl.tip_licitatie = '2'
            JOIN licitatii_ue L
               on dl.licitatii_id = L.licitatii_id
              AND L.status = 1
              AND L.Data_Limita >= '1357768800'
   where
          d.tip_domeniu = '1'
      and d.status = 1

由 Pentium10 添加

解释显示以下内容：

+---+--------+----+--------+---------------------------------------+------------------------+---+----------------------------+------+--------------------------+
| 1 | SIMPLE | d  | ref    | PRIMARY,key_status_tip_domeniu,ind_v1 | key_status_tip_domeniu | 9 | const,const                |   39 | Using where; Using index |
| 1 | SIMPLE | dl | ref    | PRIMARY,licitatii_id,licitatii_id_2   | PRIMARY                | 5 | web1db1.d.domenii_id,const | 1882 | Using index              |
| 1 | SIMPLE | L  | eq_ref | PRIMARY,data_limita,i1                | PRIMARY                | 4 | web1db1.dl.licitatii_id    |    1 | Using where              |
+---+--------+----+--------+---------------------------------------+------------------------+---+----------------------------+------+--------------------------+
于 2013-02-08T01:37:22.953 回答
0

在这里，我WHERE将末尾的子句移动到开头的子查询中，因此它不必过滤最后由INNER JOINs 创建的更多行，它已经及时正确过滤了第一个INNER JOIN. 这会运行 2 个查询，但应该更快。

SELECT Count(DISTINCT l.licitatii_id) c 
FROM   (SELECT DISTINCT licitatii_id 
        FROM   licitatii_ue l 
        WHERE  l.status = 1 
        AND    l.data_limita >= '1357768800' 
        ) l 
       INNER JOIN domenii_licitatii dl 
               ON l.licitatii_id = dl.licitatii_id 
                  AND dl.tip_licitatie = '2' 
       INNER JOIN domenii d 
               ON dl.domenii_id = d.domenii_id 
                  AND d.tip_domeniu = '1' 
                  AND d.status = 1
于 2013-02-07T11:54:45.830 回答