Question

我的查询需要很长时间，请参阅下文...

SELECT R.Email
      ,MAX(R.Id)
      ,MAX(R.Postcode)
FROM ParsedCandidates PC
    INNER JOIN Results R
        ON REPLACE(
             REPLACE(
               REPLACE(
                 REPLACE(R.[Resume], 'D:\documents\', '')
               ,'D:\CMT\Resumes\', '')
             , 'internal_', '')
           , 'monster_', '')
      = REPLACE(
          REPLACE(
            REPLACE(
              REPLACE(PC.[File], 'D:\documents\', '')
            ,'D:\CMT\Resumes\', '')
          ,'internal_', '')
        , 'monster_', '') 
WHERE CONTAINS(PC.ParsedCV, '"Marketing Executive"')
    AND R.Email IS NOT NULL
    AND R.Email <> ''
    AND R.Postcode IS NOT NULL
    AND R.Postcode <> ''
    AND EXISTS (SELECT 1
                FROM Candidates_Sourcing CS
                WHERE CS.Email = R.Email
                    AND CS.Email IS NOT NULL
                    AND CS.Email <> ''
               )
GROUP BY R.Email;

候选人采购表和结果表都有很多行。

我知道replace函数将引起可保存性问题，但是我需要这样做以确保匹配。

任何想法如何改进

Answer 1

您可以做的是在两个表上都创建持久化列，并为其编制索引

ALTER TABLE Results ADD FixedPath AS REPLACE(
             REPLACE(
               REPLACE(
                 REPLACE([Resume], 'D:\documents\', '')
               ,'D:\CMT\Resumes\', '')
             , 'internal_', '')
           , 'monster_', '') PERSISTED

CREATE NONCLUSTERED INDEX ixResults_FixedPath ON Results (FixedPath) INCLUDE (...) WHERE (...)

索引的

INCLUDE以及可能WHERE取决于您的查询。

如果您不想更改表，则可以在这两个表上创建索引视图，然后将这些视图联接起来。

CREATE VIEW v_Results 
WITH SCHEMABINDING
AS
SELECT R.Id
--   , ... other columns ...
     , REPLACE(
                 REPLACE(
                   REPLACE(
                     REPLACE(R.[Resume], 'D:\documents\', '')
                   ,'D:\CMT\Resumes\', '')
                 , 'internal_', '')
               , 'monster_', '') AS FixedPath
  FROM dbo.Resume R
 WHERE R.Email IS NOT NULL
   AND R.Email <> ''
   AND R.Postcode IS NOT NULL
   AND R.Postcode <> ''
GO

但是，索引在这里必须唯一。

CREATE UNIQUE CLUSTERED INDEX ux ON dbo.v_Results (FixedPath, Id);

创建了这两个视图之后就可以加入

SELECT ...
  FROM v_Results R WITH (NOEXPAND)
  JOIN v_ParsedCandidates PC WITH (NOEXPAND)
    ON R.FixedPath = PC.FixedPath

NOEXPAND提示可防止SQL Server将视图扩展到基础查询中。 See here。

SQL查询-替换功能使用缓慢

1 个答案: