如何提高哈希匹配的外部连接的SQL Server性能问题

Question

我是新来的性能问题。所以我不确定我的方法应该是什么。

这是超过7分钟运行的查询。

INSERT INTO SubscriberToEncounterMapping(PatientEncounterID, InsuranceSubscriberID) 
    SELECT 
     PV.PatientVisitId AS PatientEncounterID, 
     InsSub.InsuranceSubscriberID 
    FROM 
     DB1.dbo.PatientVisit PV 
    JOIN 
     DB1.dbo.PatientVisitInsurance PVI ON PV.PatientVisitId = PVI.PatientVisitId 
    JOIN 
     DB1.dbo.PatientInsurance PatIns on PatIns.PatientInsuranceId = PVI.PatientInsuranceId 
    JOIN 
     DB1.dbo.PatientProfile PP On PP.PatientProfileId = PatIns.PatientProfileId 
    LEFT OUTER JOIN 
     DB1.dbo.Guarantor G ON PatIns.PatientProfileId = G.PatientProfileId 
    JOIN 
     Warehouse.dbo.InsuranceSubscriber InsSub ON InsSub.InsuranceCarriersID = PatIns.InsuranceCarriersId 
         AND InsSub.OrderForClaims = PatIns.OrderForClaims 
         AND ((InsSub.GuarantorID = G.GuarantorId) OR (InsSub.GuarantorID IS NULL AND G.GuarantorId IS NULL)) 
    JOIN 
     Warehouse.dbo.Encounter E ON E.PatientEncounterID = PV.PatientVisitId  

执行计划指出，有一个

哈希匹配右外连接，成本89％

查询

。

没有一个右外连接查询，所以我不明白问题出在哪里。

如何使查询更有效？

这里是哈希地图详情：

Answer 1

要阐述我的意见，你可以尝试它分裂成两个查询，第一个匹配GuarantorID和第二匹配当它在InsuranceSubscriberNULL，并在Guarantor，或者如果记录完全丢失从Guarantor：

INSERT INTO SubscriberToEncounterMapping(PatientEncounterID, InsuranceSubscriberID) 
SELECT PV.PatientVisitId AS PatientEncounterID, InsSub.InsuranceSubscriberID 
FROM DB1.dbo.PatientVisit PV 
     JOIN DB1.dbo.PatientVisitInsurance PVI 
      ON PV.PatientVisitId = PVI.PatientVisitId 
     JOIN DB1.dbo.PatientInsurance PatIns 
      ON PatIns.PatientInsuranceId = PVI.PatientInsuranceId 
     JOIN DB1.dbo.PatientProfile PP 
      ON PP.PatientProfileId = PatIns.PatientProfileId 
     JOIN DB1.dbo.Guarantor G 
      ON PatIns.PatientProfileId = G.PatientProfileId 
     JOIN Warehouse.dbo.InsuranceSubscriber InsSub 
      ON InsSub.InsuranceCarriersID = PatIns.InsuranceCarriersId 
      AND InsSub.OrderForClaims = PatIns.OrderForClaims 
      AND InsSub.GuarantorID = G.GuarantorId 
     JOIN Warehouse.dbo.Encounter E 
      ON E.PatientEncounterID = PV.PatientVisitId 
UNION ALL 
SELECT PV.PatientVisitId AS PatientEncounterID, InsSub.InsuranceSubscriberID 
FROM DB1.dbo.PatientVisit PV 
     JOIN DB1.dbo.PatientVisitInsurance PVI 
      ON PV.PatientVisitId = PVI.PatientVisitId 
     JOIN DB1.dbo.PatientInsurance PatIns 
      ON PatIns.PatientInsuranceId = PVI.PatientInsuranceId 
     JOIN DB1.dbo.PatientProfile PP 
      ON PP.PatientProfileId = PatIns.PatientProfileId 
     JOIN Warehouse.dbo.InsuranceSubscriber InsSub 
      ON InsSub.InsuranceCarriersID = PatIns.InsuranceCarriersId 
      AND InsSub.OrderForClaims = PatIns.OrderForClaims 
      AND InsSub.GuarantorID IS NULL 
     JOIN Warehouse.dbo.Encounter E 
      ON E.PatientEncounterID = PV.PatientVisitId 
WHERE NOT EXISTS 
     ( SELECT 1 
      FROM DB1.dbo.Guarantor G 
      WHERE PatIns.PatientProfileId = G.PatientProfileId 
      AND  InsSub.GuarantorID IS NOT NULL 
     ); 

Answer 2

的联接基础上，以减少每个返回的记录数加入的能力我会重新排序。无论哪个加入可以减少返回的数量或记录都会提高效率。然后执行外部连接。此外，表锁定总是可能是一个问题，所以添加（nolock）以防止记录被锁定。

也许像这样的东西将工作与一点点调整。

INSERT INTO SubscriberToEncounterMapping (
    PatientEncounterID 
    , InsuranceSubscriberID 
    ) 
SELECT PV.PatientVisitId AS PatientEncounterID 
    , InsSub.InsuranceSubscriberID 
FROM DB1.dbo.PatientVisit PV WITH (NOLOCK) 
INNER JOIN Warehouse.dbo.Encounter E WITH (NOLOCK) 
    ON E.PatientEncounterID = PV.PatientVisitId 
INNER JOIN DB1.dbo.PatientVisitInsurance PVI WITH (NOLOCK) 
    ON PV.PatientVisitId = PVI.PatientVisitId 
INNER JOIN DB1.dbo.PatientInsurance PatIns WITH (NOLOCK) 
    ON PatIns.PatientInsuranceId = PVI.PatientInsuranceId 
INNER JOIN DB1.dbo.PatientProfile PP WITH (NOLOCK) 
    ON PP.PatientProfileId = PatIns.PatientProfileId 
INNER JOIN Warehouse.dbo.InsuranceSubscriber InsSub WITH (NOLOCK) 
    ON InsSub.InsuranceCarriersID = PatIns.InsuranceCarriersId 
     AND InsSub.OrderForClaims = PatIns.OrderForClaims 
LEFT JOIN DB1.dbo.Guarantor G WITH (NOLOCK) 
    ON PatIns.PatientProfileId = G.PatientProfileId 
     AND (
      (InsSub.GuarantorID = G.GuarantorId) 
      OR (
       InsSub.GuarantorID IS NULL 
       AND G.GuarantorId IS NULL 
       ) 
      )