Question

我有这个问题：

SELECT 
    c.violatorname
FROM 
    dbo.crimecases AS c,
    dbo.people AS p
WHERE 
    REPLACE(c.violatorname, ' ', '') = CONCAT(CONCAT(CONCAT(p.firstname, p.secondname), p.thirdname), p.lastname);

查询非常慢，我需要使用replace函数在violatorname列上创建索引。有任何想法吗？

Answer 1

我建议您添加computed columns并在其上创建index。

ALTER TABLE crimecases
  ADD violatornameProcessed AS Replace(violatorname, ' ', '') PERSISTED 

ALTER TABLE people
  ADD fullName AS Concat(firstname, secondname, thirdname, lastname) PERSISTED

Persisted会将计算出的数据存储在磁盘上，而不是每次都计算。现在在其上创建索引。

CREATE INDEX Nix_crimecases_violatornameProcessed
  ON crimecases (violatornameProcessed)
  include (violatorname)

CREATE INDEX Nix_people_fullName
  ON people (fullName)

查询可以写成

SELECT c.violatorname
FROM   dbo.crimecases AS c
       INNER JOIN dbo.people AS p
               ON c.violatornameProcessed = p.fullName

SQL Server索引 - 想法？

1 个答案: