性能訂貨

Question

時，對於下面的腳本：

DECLARE @StartDate DATETIME, 
     @EndDate DATETIME, 
     @SearchSt INT 

SET @StartDate = '2014-02-01' 
SET @EndDate = '2014-02-20' 
SET @SearchSt = 2; 

WITH DSAEvent 
AS 
(
SELECT ROW_NUMBER() OVER 
     (
     PARTITION BY e.TT_TAG_ID 
      ORDER BY e.TT_TAG_ID, 
         e.DSA_Event_Date, 
         e.DSA_Time_In, 
         e.DSA_Time_Out, 
         e.TAG_Inter_DSA_Seq_No 
     ) AS rn, 
     e.EventID, e.TT_TAG_ID, e.DSA_ID, e.DSA_Purpose_ID, e.DSA_Time_In, 
     e.DSA_Time_Out, e.DSA_Duration, e.Sh_DSA_Event_Record_Type, 
     e.TAG_Inter_DSA_Seq_No, 
     ISNULL((
       SELECT CASE 
          WHEN e.DSA_Purpose_ID = 3 THEN ISNULL(T_No, 0) 
          ELSE -1 
         END 
        FROM DSAs 
        WHERE St_ID = @SearchSt 
        AND DSA_ID = e.DSA_ID 
       ), -1) AS T_No 
    FROM SH_DSA_EVENT_WORKING e 
    WHERE e.Store_ID = @SearchSt 
    AND e.DSA_Event_Date >= @StartDate 
    AND e.DSA_Event_Date <= @EndDate 
    AND e.Sh_ID IS NULL 
) 

SELECT p.TT_TAG_ID, p.DSA_ID, p.DSA_Purpose_ID, p.DSA_Time_In, 
     p.DSA_Time_Out, p.DSA_Duration, p.Sh_DSA_Event_Record_Type, 
     p.TAG_Inter_DSA_Seq_No, p.Till_No, 
     ABS(DATEDIFF(
       second, 
       ISNULL(n.DSA_Time_In, '2000-01-01 00:00:00'), 
       ISNULL(p.DSA_Time_Out, '2000-01-01 00:00:00')) 
      ), 
     td.TAG_Asset_Type_ID, p.EventID 
    FROM DSAEvent p 
     LEFT JOIN DSAEvent n ON p.rn = n.rn - 1 AND p.TT_TAG_ID = n.TT_TAG_ID 
     LEFT JOIN TAG_DETAIL td ON td.TT_TAG_ID = p.TT_TAG_ID 
    WHERE ISNULL(td.St_ID, @SearchSt) = @SearchSt 
    ORDER BY td.TT_TAG_ID, p.DSA_Time_In, p.DSA_Time_Out, 
      p.TAG_Inter_DSA_Seq_No, p.rn 

這似乎一直無法進行運行。我已經縮小到最後的ORDER子句。

如果我註釋掉ORDER子句，我會在13秒內返回741594行。如果我讓腳本以ORDER子句運行，它將運行超過13個小時。

我錯過了什麼，或者如何找出導致延遲的原因？

Answer 1

你必須簡化這個測試。拔出連接並選擇標準和度量。一次添加一個項目並重新測量以查看問題出在哪裏。另外，學習執行計劃

Answer 2

看來問題是ORDER BY td.TT_TAG_ID。 如果LEFT JOIN爲該列提供空值，那麼它是如何定購的？

你可以嘗試ORDER BY p.TT_TAG_ID