Question

注意：

正如我想的那样，真正的问题是因为我用于tagids的IN子句。更改查询的部分文本搜索没有多大帮助。知道如何改进查询吗？

在服务器上运行时查询耗时太长。这里Partha S是用户输入的搜索项。表联系人包含个人信息，标签包含类别名称和ID;和contacts2tags表包含contactid和tagid，其值分别与contact和tags中的id类似。

    SELECT *
    FROM
    (
    SELECT *,
     IF
    (
     first_name LIKE 'Partha S'
    OR last_name LIKE 'Partha S'
    OR phone_number LIKE 'Partha S'
    OR mobile_number LIKE 'Partha S'
    OR email_address LIKE 'Partha S'
    OR address LIKE 'Partha S'
    OR organization LIKE 'Partha S'
    OR other LIKE 'Partha S'
    OR sector LIKE 'Partha S'
    OR designation LIKE 'Partha S'
    OR concat ( first_name,  ' ',  last_name ) LIKE 'Partha S'
    OR concat ( last_name,  ' ',  first_name ) LIKE 'Partha S',
     1,
     0 )
     as exact,
     IF
    (
    (
     first_name LIKE '%Partha%'
    OR last_name LIKE '%Partha%'
    OR phone_number LIKE '%Partha%'
    OR mobile_number LIKE '%Partha%'
    OR email_address LIKE '%Partha%'
    OR address LIKE '%Partha%'
    OR organization LIKE '%Partha%'
    OR other LIKE '%Partha%'
    OR sector LIKE '%Partha%'
    OR designation LIKE '%Partha%' )
    AND
    (
     first_name LIKE '%S%'
    OR last_name LIKE '%S%'
    OR phone_number LIKE '%S%'
    OR mobile_number LIKE '%S%'
    OR email_address LIKE '%S%'
    OR address LIKE '%S%'
    OR organization LIKE '%S%'
    OR other LIKE '%S%'
    OR sector LIKE '%S%'
    OR designation LIKE '%S%' )
    ,
     1,
     0 )
     as normal
    FROM contacts
    WHERE id in
    (
    SELECT DISTINCT contacts.id
    from contacts INNER
    JOIN contacts2tags ON contacts.id = contacts2tags.contactid
    WHERE ( tagid in ( 178 ) ) )
     )
     d
    WHERE exact = 1
    OR normal = 1
    ORDER BY exact desc,
     last_name asc LIMIT 0,
     20

更新根据建议，我删除了LIKE运算符以进行精确搜索，并在后一种情况下使用MATCH（..）AGAINST（..）而不是LIKE。虽然第一次更改确实提高了性能，但使用MATCH（）AGAINST（）并没有出人意料地改变执行时间。这是更新的查询。 PS我尝试使用MATCH（所有cols）AGAINST（搜索项目）和MATCH（单个cols）AGAINST（搜索项目）结合OR。请建议。感谢

     SELECT *
    FROM
    (
    SELECT *,
     IF
    (
         first_name ='Partha S'
       OR last_name ='Partha S'
       OR phone_number ='Partha S'
       OR mobile_number ='Partha S'
       OR email_address = 'Partha S'
       OR address ='Partha S'
       OR organization ='Partha S'
       OR other ='Partha S'
       OR sector ='Partha S'
       OR designation ='Partha S'
       OR concat ( first_name,  ' ',  last_name ) ='Partha S'
       OR concat ( last_name,  ' ',  first_name ) ='Partha S',
       1,
       0 )
      as exact,
       IF
      ( match(first_name,last_name,phone_number,mobile_number,email_address,  address,organization,other,sector,designation) against( 'Partha')                 
    OR  match(first_name,last_name,phone_number,mobile_number,email_address,address,organization,other,sector,designation) against( 'S')


    ,
    1,
    0 )
     as normal
    FROM contacts
    WHERE id in
    (
    SELECT DISTINCT contacts.id
    from contacts INNER
    JOIN contacts2tags ON contacts.id = contacts2tags.contactid
    WHERE ( tagid in ( 178 ) ) )
     )
     d
    WHERE exact = 1
    OR normal = 1
    ORDER BY exact desc,
     last_name asc LIMIT 0,
      20

Answer 1

一个优化是在exact情况下，您不需要使用LIKE（您只应将它与通配符一起使用 - ％）。

你可以做的另一件事就是为你要搜索的文件添加一个INDEX。

此外，只有当您使用MyISSAM作为存储引擎（对于该表）时，您才能使用全文搜索这样

SELECT * FROM normal WHERE MATCH（title，body）AGAINST（'Queried_string'）

first_name LIKE '%S%'
OR last_name LIKE '%S%'
OR phone_number LIKE '%S%'
OR mobile_number LIKE '%S%'
OR email_address LIKE '%S%'
OR address LIKE '%S%'
OR organization LIKE '%S%'
OR other LIKE '%S%'
OR sector LIKE '%S%'
OR designation LIKE '%S%' )

似乎对整个过程带来的价值很小。

希望这有帮助。

Answer 2

这不仅仅是LIKE的所有内容，还包括OR s。即使对于使用LIKE的条件，也会使用索引。因此，为了加快此查询速度，您可以为每个表创建一个非常大的索引，它将您搜索的所有字段组合在一起。

但是如果你真的想构建一个搜索引擎，你可能会考虑使用Sphinx或ElasticSearch而不是像这样的MySQL怪物查询。

Answer 3

您可能希望了解MySQL的match()和against()功能。

以下是其文档中的一些示例代码

mysql> CREATE TABLE articles (
    ->   id INT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
    ->   title VARCHAR(200),
    ->   body TEXT,
    ->   FULLTEXT (title,body)
    -> ) ENGINE=MyISAM;
Query OK, 0 rows affected (0.00 sec)

mysql> INSERT INTO articles (title,body) VALUES
    -> ('MySQL Tutorial','DBMS stands for DataBase ...'),
    -> ('How To Use MySQL Well','After you went through a ...'),
    -> ('Optimizing MySQL','In this tutorial we will show ...'),
    -> ('1001 MySQL Tricks','1. Never run mysqld as root. 2. ...'),
    -> ('MySQL vs. YourSQL','In the following database comparison ...'),
    -> ('MySQL Security','When configured properly, MySQL ...');
Query OK, 6 rows affected (0.00 sec)
Records: 6  Duplicates: 0  Warnings: 0

mysql> SELECT * FROM articles
    -> WHERE MATCH (title,body) AGAINST ('database');
+----+-------------------+------------------------------------------+
| id | title             | body                                     |
+----+-------------------+------------------------------------------+
|  5 | MySQL vs. YourSQL | In the following database comparison ... |
|  1 | MySQL Tutorial    | DBMS stands for DataBase ...             |
+----+-------------------+------------------------------------------+
2 rows in set (0.00 sec)

在此处阅读更多 - http://dev.mysql.com/doc/refman/4.1/en/fulltext-natural-language.html

使用LIKE运算符为10k记录优化mysql查询

3 个答案: