2

有一个 SQL union all 查询和 3 个 union all 查询。在查询中添加文本列后，查询执行时间发生了显着变化CAST(c.getQuestionId AS VARCHAR(300))。使用的数据库是SQL SERVER 2014，请性能调优高手帮忙。

上创建了 3 个索引JcccustomersAssessmentProxy。这是一个包含 8000 万条记录的表。仅在第 3 个查询中提及显式使用索引（即 ( NOLOCK, INDEX=IX_AssessmentProxy_myJcAssessmentContext)）

myJcAssessmentContext 上有一个非聚集索引

getmycoordtoyplanver 上有一个非聚集索引

getMyEventItem 上有一个非聚集索引

 SELECT     ass.P_KEY
            ,ass.SS_CODE
            ,CAST(evp.EVENT_SSID AS VARCHAR(11)) AS EVENT_SSID
            ,CAST(QUESTIONNUMBER AS VARCHAR(3))                             AS EVENT_NO
            ,CAST(ISNULL(CAST(TEMPLATEVERSION AS VARCHAR), 0) AS INT)       AS TEMPLATEVERSION
            ,ISNULL(CAST(TEMPLATENAME AS VARCHAR(50)), ' ')                 AS TEMPLATENAME
            ,evp.ASS_DATE
            ,ISNULL(ANSWERNUMBER, 0)                                        AS ANSWER_NO
            ,ass.CASE_SSID
            ,ass.RE_SSID
            ,ass.RE_DATE
            ,ass.EPISODE_SSID
            ,ass.[SERVICE]
            ,ass.SERVICE_DESC
            ,ass.TAM_KEY 
            ,ass.PRv_KEY
            ,CAST(QUESTIONNUMBER AS VARCHAR(3))                 AS QUESTION_NO
            ,ISNULL(CONVERT(VARCHAR(100), REPLACE(REPLACE(CAST(QUESTIONTEXT AS VARCHAR(650)), char(10), ''), char(13), ' ')), ' ') AS QUESTION_TEXT
            ,ISNULL(CAST(ANSWER  AS VARCHAR(125)), ' ')         AS ANSWER_TEXT
            ,a.MyAssessment                                     AS ASSESSMENT_SSID
-----------------------------------------------------------------------------------------

            ,CAST(RIGHT(a.getMyCoordtoyPlanVer, 10) AS INT)     AS toy_PLAN_VERSION_SSID    
            ,CAST(RIGHT(a.myJcAssessmentContext, 10) AS INT)        AS CONTEXT_FORM_SSID
-----------------------------------------------------------------------------------------           
            ,ass.RECORD_DATE
                                 **,CAST(a.getQuestionId AS VARCHAR(300) )                    AS QUESTION_ID  /*NEW Text Column ,this remove the parallelism*/**
FROM        SourceFeed.dbo.JcccustomersAssessmentProxy  AS a WITH(NOLOCK)
            INNER JOIN
            TEMP_DATABASE.dbo.jsystemReport_AllEventItems_AllPersons    evp WITH(NOLOCK)
            ON a.getMyEventItem = evp.oid 


            INNER JOIN
            TEMP_DATABASE.dbo.jsystemAssessment                     ass WITH(NOLOCK)
            ON evp.getcustomersId = ass.customersID
            AND evp.EVENT_SSID = ass.EVENTID


UNION ALL

SELECT      ass.P_KEY
            ,ass.SS_CODE
            ,CAST(csp.ENT_SSID AS VARCHAR(11)) AS EVENT_SSID
            ,CAST(jcc.QUESTIONNUMBER AS VARCHAR(3)) AS  EVENT_NO
            ,CAST(ISNULL(CAST(CAST(jcc.TEMPLATEVERSION AS VARCHAR) AS VARCHAR), 0) AS INT) AS TEMPLATEVERSION
            ,ISNULL(CAST(jcc.TEMPLATENAME AS VARCHAR(50)), ' ') AS TEMPLATENAME
            ,csp.ASSESSMENT_DATE
            ,ISNULL(jcc.ANSWERNUMBER, 0) AS ANSWER_NO
            ,ass.CASE_SSID
            ,ass.REF_SSID
            ,ass.RE_DATE
            ,ass.EPISODE_SSID
            ,ass.[SERVICE]
            ,ass.SERVICE_DESC
            ,ass.TEAM_KEY 
            ,ass.PROVIDER_KEY
            ,CAST(ISNULL(jcc.QUESTIONNUMBER, 0) AS VARCHAR(3))  AS QUESTION_NO
            ,isnull(CONVERT(VARCHAR(100), replace(replace(CAST(jcc.QUESTIONTEXT AS VARCHAR(650)), char(10), ''), char(13), ' ')), ' ') AS QUESTION_TEXT
            ,ISNULL(CAST(jcc.ANSWER  AS VARCHAR(125)), ' ') AS ANSWER_TEXT
            ,jcc.MyAssessment AS ASSESSMENT_SSID
-----------------------------------------------------------------------------------------

            ,CAST(RIGHT(jcc.getMyCoordtoyPlanVer, 10) AS INT)       AS toy_PLAN_VERSION_SSID    
            ,CAST(RIGHT(jcc.myJcAssessmentContext, 10) AS INT)      AS CONTEXT_FORM_SSID
-----------------------------------------------------------------------------------------           
            ,ass.RECORD_DATE
                                 **,CAST(jcc.getQuestionId AS VARCHAR(300) )                    AS QUESTION_ID  /*NEW Text Column ,this remove the parallelism*/**
FROM        TEMP_DATABASE.dbo.jsystemReport_toySpell                csp WITH(NOLOCK)
            INNER JOIN
            TEMP_DATABASE.dbo.jsystemAssessment                     ass WITH(NOLOCK)
            ON csp.getcustomersId = ass.customersID
            AND csp.EVENT_SSID = ass.EVENTID
            LEFT OUTER JOIN
            SourceFeed.dbo.JcccustomersAssessmentProxy  jcc WITH(NOLOCK)
            ON csp.OID = jcc.getmycoordtoyplanver

WHERE       NOT EXISTS (SELECT  tp1.OID
                        FROM    TEMP_DATABASE.dbo.AssessmentTransferPart1   tp1
                        WHERE   tp1.OID = jcc.OID)

UNION ALL

SELECT      ass.P_KEY
            ,ass.SS_CODE
            ,CAST(a.EVENT_SSID AS VARCHAR(11)) AS EVENT_SSID
            ,CAST(CAST(C.QUESTIONNUMBER AS INT) AS CHAR(3)) AS EVENT_NO
            ,CAST(ISNULL(CAST(C.TEMPLATEVERSION AS VARCHAR), 0) AS INT) AS TEMPLATEVERSION
            ,ISNULL(CAST(C.TEMPLATENAME AS VARCHAR(50)), ' ') AS TEMPLATENAME
            ,a.ASSESSMENT_DATE
            ,ISNULL(C.ANSWERNUMBER, 0) AS ANSWER_NO
            ,ass.CASE_SSID
            ,ass.REL_SSID
            ,ass.REAL_DATE
            ,ass.EPISODE_SSID
            ,ass.[SERVICE]
            ,ass.SERVICE_DESC
            ,ass.TEAM_KEY 
            ,ass.PROVIDER_KEY
            ,CAST(ISNULL(CAST(C.QUESTIONNUMBER AS INT), 0) AS VARCHAR(3))  AS QUESTION_NO
            ,isnull(CONVERT(VARCHAR(100), CAST(C.QUESTIONTEXT AS VARCHAR(650))), ' ') AS QUESTION_TEXT
            ,ISNULL(CAST(C.ANSWER  AS VARCHAR(125)), ' ') AS ANSWER_TEXT
            ,a.MyAssessment AS ASSESSMENT_SSID
-----------------------------------------------------------------------------------------

            ,CAST(RIGHT(C.getMyCoordtoyPlanVer, 10) AS INT)     AS toy_PLAN_VERSION_SSID    
            ,CAST(RIGHT(C.myJcAssessmentContext, 10) AS INT)        AS CONTEXT_FORM_SSID
-----------------------------------------------------------------------------------------           
            ,ass.RECORD_DATE
                                 **,CAST(c.getQuestionId AS VARCHAR(300) )**                    AS QUESTION_ID  /*NEW Text Column ,this remove the parallelism*/
FROM        SourceFeed.dbo.toyClusterReviewAssessment       B WITH(NOLOCK)
            INNER JOIN
            SourceFeed.dbo.JcccustomersAssessmentProxy      C WITH(NOLOCK, INDEX=IX_AssessmentProxy_myJcAssessmentContext)
            ON B.myJCJccUserFormContext = C.myJcAssessmentContext 
            INNER JOIN
            SourceFeed.dbo.JcccustomersAssessmentScoreProxy D WITH(NOLOCK)
            ON B.myJCJccUserFormContext = D.myJcAssessmentContext


            INNER JOIN
            TEMP_DATABASE.dbo.jsystemReport_toyClusterReviewEvent_AllPersons    A WITH(NOLOCK)
            ON a.myAssessment = B.oid
            INNER JOIN
            TEMP_DATABASE.dbo.jsystemAssessment             ass WITH(NOLOCK)
            ON a.getcustomersId = ass.customersID
            AND a.EVENT_SSID = ass.EVENTID
WHERE       NOT EXISTS (SELECT  OID
                        FROM    (SELECT     tp1.OID
                                    FROM    TEMP_DATABASE.dbo.AssessmentTransferPart1   tp1
                                    UNION ALL
                                    SELECT  tp2.OID
                                    FROM    TEMP_DATABASE.dbo.AssessmentTransferPart2   tp2) jcc
                        WHERE   jcc.OID = C.OID)

这是实际执行计划的链接。

在JccClientAssessmentProxy jccWITH(NOLOCK,INDEX=IX_AssessmentProxy_GETMYCOORDCAREPLANVER) 添加索引后，这是新的执行计划。

4

1 回答 1

1

有问题的部分是：

  ,CAST(a.getQuestionId AS VARCHAR(300)) AS QUESTION_ID  
  FROM  cnlPjccR_Report.dbo.JccClientAssessmentProxy AS a  
        WITH(NOLOCK,INDEX=IX_AssessmentProxy_getMyEventItem)
  INNER JOIN ...

并且问题在您的两个 UNION ALL 子查询中重复出现。

您的执行计划显示昂贵的密钥查找。

第二种方法是看是否可以创建一个满足整个查询或至少消除键查找的“覆盖索引”。“覆盖索引”只是一个非聚集索引，它包含满足整个查询所需的所有列，或者在我们的例子中，消除了对键查找操作的需要。一个挑战是获取生成键查找的列的列表。您可以在 SQL Server Management Studio (SSMS) 中通过右键单击键查找运算符，然后选择“属性”来执行此操作。然后在“属性”窗口中找到“输出列表”行，然后单击省略号按钮。这将打开一个窗口（见下文），其中列出了键查找正在查找的所有列。您可以使用此列表来帮助您决定是否以及如何创建索引来“覆盖”查询或键查找。

在您的情况下，应包含以下列来创建覆盖索引：

[cnlPjccR_Report].[dbo].[JccClientAssessmentProxy].answer; 
[cnlPjccR_Report].[dbo].[JccClientAssessmentProxy].answerNumber; 
[cnlPjccR_Report].[dbo].[JccClientAssessmentProxy].getMyCoordCarePlanVer; 
[cnlPjccR_Report].[dbo].[JccClientAssessmentProxy].getQuestionId; 
[cnlPjccR_Report].[dbo].[JccClientAssessmentProxy].myAssessment; 
[cnlPjccR_Report].[dbo].[JccClientAssessmentProxy].myJcAssessmentContext; 
[cnlPjccR_Report].[dbo].[JccClientAssessmentProxy].questionNumber; 
[cnlPjccR_Report].[dbo].[JccClientAssessmentProxy].questionText; 
[cnlPjccR_Report].[dbo].[JccClientAssessmentProxy].templateName; 
[cnlPjccR_Report].[dbo].[JccClientAssessmentProxy].templateVersion

可能您的索引不包含getQuestionId列，并且该事实已创建较慢Key lookup或RID lookup在您的查询执行计划中。

另请参阅此处或此答案。

于 2017-08-15T06:31:50.160 回答