如何提高哈希匹配的外部連接的SQL Server性能問題

Question

我是新來的性能問題。所以我不確定我的方法應該是什麼。

這是超過7分鐘運行的查詢。

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  

執行計劃指出，有一個

哈希匹配右外連接，成本89％

查詢

。

沒有一個右外連接查詢，所以我不明白問題出在哪裏。

如何使查詢更有效？

這裏是哈希地圖詳情：

Answer 1

要闡述我的意見，你可以嘗試它分裂成兩個查詢，第一個匹配GuarantorID和第二匹配當它在InsuranceSubscriberNULL，並在Guarantor，或者如果記錄完全丟失從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

的聯接基礎上，以減少每個返回的記錄數加入的能力我會重新排序。無論哪個加入可以減少返回的數量或記錄都會提高效率。然後執行外部連接。此外，表鎖定總是可能是一個問題，所以添加（nolock）以防止記錄被鎖定。

也許像這樣的東西將工作與一點點調整。

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 
       ) 
      )