sql - CONTAINS 与条件逻辑组合时的效率问题

Question

我刚刚对用于返回一些搜索结果的查询的 WHERE 子句进行了修改。

我开始于:

WHERE 
(
    CONTAINS(MD_Entity.Forename, @Forename) 
    AND CONTAINS(MD_Entity.Family_Name, @FamilyName)
) 
AND 
(
    MD_Entity_Role.Role_Type = 2
    OR MD_Entity.Do_Not_Transact = 1
)

并将其更改为:

WHERE 
(
    CONTAINS(MD_Entity.Forename, @Forename) 
    AND CONTAINS(MD_Entity.Family_Name, @FamilyName) 
    AND MD_Entity_Role.Role_Type = 2
)
OR 
(
    CONTAINS(MD_Entity.Family_Name, @Forename) 
    AND CONTAINS(MD_Entity.Family_Name, @FamilyName) 
    AND MD_Entity.Do_Not_Transact = 1
)

查询从立即返回结果变为花费一分钟左右的时间。

我不是 SQL 专家，所以我显然在这里犯了一些效率错误。首先，有人可以解释为什么效率下降如此之大，其次，是否有更快的方法来完成我在这里所做的事情？

Answer 1

对条件重新排序，第一个速度更快

WHERE 
(   1 = 1
    AND MD_Entity_Role.Role_Type = 2
    AND CONTAINS(MD_Entity.Forename, @Forename) 
    AND CONTAINS(MD_Entity.Family_Name, @FamilyName) 

)
OR 
(   1 = 1
    AND MD_Entity.Do_Not_Transact = 1
    AND CONTAINS(MD_Entity.Family_Name, @Forename) 
    AND CONTAINS(MD_Entity.Family_Name, @FamilyName) 
)

使用UNION避免缓慢的OR条件

WHERE 
    1 = 1
    AND MD_Entity_Role.Role_Type = 2
    AND CONTAINS(MD_Entity.Forename, @Forename) 
    AND CONTAINS(MD_Entity.Family_Name, @FamilyName) 

UNION

WHERE
    1 = 1
    AND MD_Entity.Do_Not_Transact = 1
    AND CONTAINS(MD_Entity.Family_Name, @Forename) 
    AND CONTAINS(MD_Entity.Family_Name, @FamilyName)