針對多個表的SQL匹配查詢的性能問題

Question

我在運行使用MyISAM數據庫的SQL查詢時遇到性能問題。

要介紹這一點，我有3個表：
表：（發動機的MyISAM總記錄數：1847）甲
表：（發動機的MyISAM總記錄數：1110）乙
表：C（發動機的MyISAM。總記錄數：57867）

現在我正在查詢花費623秒得到執行，並且有時它發生，從服務器的連接（同樣是本地主機被中止的情況下）。

下面是我執行查詢：

SELECT MATCH(A.title, A.description) AGAINST('Computer Graphic Artist') AS 'Score', 
    A.code AS 'Code', 
    B.cluster AS 'Cluster', 
    B.pathway AS 'Pathway', 
    A.title AS 'Role', 
    A.description AS 'Description' 
FROM B 
INNER JOIN A ON B.code = A.code 
INNER JOIN C ON B.code = C.code 
WHERE MATCH(A.title, A.description) AGAINST('Computer Graphic Artist') 
    OR MATCH(B.cluster, B.pathway, B.descripton) AGAINST('Computer Graphic Artist') 
    OR MATCH(C.title) AGAINST('Computer Graphic Artist') 
ORDER BY Score DESC, B.cluster ASC 

您也可以參考Pastie（如果你覺得無法看到這個SQL）。我已經在適用的地方添加了FULLTEXT屬性。

注：表A，B和C也有少量重複記錄。

請讓我知道，我如何優化這個SQLfor快速輸出。

Answer 1

要做的第一件事就是確保你確切的集合你從每個表查詢的列有一個適當的FULLTEXT指數：

alter table A add fulltext index a_fti (title,description); 
alter table B add fulltext index b_fti (cluster, pathway, descripton); 
alter table C add fulltext index c_fti (title); 

然後我會建議重寫查詢中使用UNION而不是OR。使用這種方法，我已經從FULLTEXT搜索中獲得了更好的性能，特別是在MySQL中。

下面是一個使用您的查詢的例子：

select Score, Code, Cluster, Pathway, Role, Description 
from 
(
SELECT MATCH(A.title, A.description) AGAINST('Computer Graphic Artist') AS 'Score', 
    A.code AS 'Code', 
    B.cluster AS 'Cluster', 
    B.pathway AS 'Pathway', 
    A.title AS 'Role', 
    A.description AS 'Description' 
FROM B 
INNER JOIN A ON B.code = A.code 
INNER JOIN C ON B.code = C.code 
WHERE MATCH(A.title, A.description) AGAINST('Computer Graphic Artist') 
UNION 
SELECT MATCH(A.title, A.description) AGAINST('Computer Graphic Artist') AS 'Score', 
    A.code AS 'Code', 
    B.cluster AS 'Cluster', 
    B.pathway AS 'Pathway', 
    A.title AS 'Role', 
    A.description AS 'Description' 
FROM B 
INNER JOIN A ON B.code = A.code 
INNER JOIN C ON B.code = C.code 
WHERE MATCH(B.cluster, B.pathway, B.descripton) AGAINST('Computer Graphic Artist') 
UNION 
SELECT MATCH(A.title, A.description) AGAINST('Computer Graphic Artist') AS 'Score', 
    A.code AS 'Code', 
    B.cluster AS 'Cluster', 
    B.pathway AS 'Pathway', 
    A.title AS 'Role', 
    A.description AS 'Description' 
FROM B 
INNER JOIN A ON B.code = A.code 
INNER JOIN C ON B.code = C.code 
WHERE MATCH(C.title) AGAINST('Computer Graphic Artist') 
) as sub_query 
ORDER BY Score DESC, Cluster ASC