SQL 如何优化从临时 table 插入到 table

Question

我创建了从各种项目（数据库）动态收集一些记录到临时 table 中的过程，然后从那个临时 table 我插入到 table 中。使用 WHERE statement ，但不幸的是，当我检查执行计划时，我发现这个查询部分需要很多负载。我如何优化此 INSERT 部分或 WHERE 语句？

INSERT INTO dbo.PROJECTS_TESTS ( PROJECTID, ANOTHERTID, DOMAINID, is_test)
    SELECT * FROM #temp_Test AS tC
    WHERE NOT EXISTS (SELECT TOP 1 1 
                        FROM dbo.PROJECTS_TESTS AS ps WITH (NOLOCK)
                        WHERE ps.PROJECTID = tC.projectId 
                        AND ps.ANOTHERTID = tC.anotherLink 
                        AND ps.DOMAINID = tC.DOMAINID 
                        AND ps.is_test = tC.test_project 
                        )

Answer 1

我认为 JOIN 比 EXISTS 更好。根据您加入条件的基数（目前在您的 WHERE 中），您可能也需要 DISTINCT。

INSERT INTO dbo.PROJECTS_TESTS ( PROJECTID, ANOTHERTID, DOMAINID, is_test)
    SELECT <maybe distinct> tC.* FROM #temp_Test AS tC
    LEFT OUTER JOIN  FROM dbo.PROJECTS_TESTS AS ps on
                        ps.PROJECTID = tC.projectId 
                        AND ps.ANOTHERTID = tC.anotherLink 
                        AND ps.DOMAINID = tC.DOMAINID 
                        AND ps.is_test = tC.test_project 

where ps.PROJECT ID IS NULL

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SQL 如何优化从临时 table 插入到 table

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