Sql 将包含与条件逻辑结合时的效率问题

我刚刚修改了我用来返回一些搜索结果的查询的

WHERE

子句

我从以下几点开始：

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到只需一分钟

---

我不是

SQL

专家，所以我显然在这里犯了一些效率失礼的错误。首先，有人能解释一下为什么效率下降得如此之快吗？其次，有没有更快的方法来完成我在这里所做的事情？

重新排序条件，第一个越快

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

避免慢速

或
情况

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) 

试试这个

它可能允许查询优化器更快地进行筛选

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

谢谢。工会起了很大的作用。很高兴知道。我也会试试这个。谢谢。