如何提高跨多個數據庫的查詢的性能？

Question

這是我查詢將近20分鍾。 請建議我進行更改以提高效果

SELECT DISTINCT
    CONVERT(varchar(10),x.notice_date,120)  Date,
    Y.branch_name,
    count(case when x.status='broken' and x.branch_name=y.branch_name then 1 end) 
      Broken,
    count(case when x.type='Lote' and x.branch_name=y.branch_name then 1 end)
      Lost,
    (   SELECT COUNT(A.car_no)
        FROM DB2.dbo.z_mat A
        WHERE DateAdd(Day, DateDiff(Day, 0,a.notice_date), 0)
              = DateAdd(Day, DateDiff(Day, 0,x.notice_date), 0)
          AND a.branch_name=y.branch_name
    ) mat,
    (   SELECT COUNT(B.car_no)
        FROM DB2.dbo.z_cat B
        WHERE DateAdd(Day, DateDiff(Day, 0,b.notice_date), 0)
              = DateAdd(Day, DateDiff(Day, 0,x.notice_date), 0)
          AND b.branch_name=y.branch_name
    ) cat,
    (   SELECT COUNT(C.car_no)
        FROM DB2.dbo.z_pat C
        WHERE DateAdd(Day, DateDiff(Day, 0,c.notice_date), 0)
              = DateAdd(Day, DateDiff(Day, 0,x.notice_date), 0)
          AND c.branch_name=y.branch_name
    ) pat
FROM DB1.dbo.Cars x
   , DB2.dbo.Branch Y
WHERE DateAdd(Day, DateDiff(Day, 0,x.notice_date), 0)
      > '2011-01-01'
GROUP BY CONVERT(varchar(10),x.notice_date,120)
       , DateAdd(Day, DateDiff(Day, 0,x.notice_date), 0)
       , y.branch_name

Answer 1

這可能會有所幫助。 試試看。

SELECT          
DISTINCT        CONVERT(VARCHAR(10), car.notice_date, 120) AS NoticeDate
            ,   brc.branch_name
            ,   COUNT(CASE WHEN car.status = 'broken'   AND car.branch_name = brc.branch_name   THEN 1 END) Broken
            ,   COUNT(CASE WHEN car.status = 'Lote'     AND car.branch_name = brc.branch_name   THEN 1 END) Lost
            ,   mat.mat_count
            ,   cat.cat_count
            ,   pat.pat_count
FROM            DB1.dbo.Cars        car
            ,   DB2.dbo.Branch      brc
CROSS APPLY     (   
                    SELECT  COUNT(mat.car_no)   mat_count
                    FROM    DB2.dbo.z_mat       mat
                    WHERE   DATEDIFF(d, mat.notice_date, car.notice_date) = 0
                    AND     mat.branch_name     = brc.branch_name
                ) mat
CROSS APPLY     (   
                    SELECT  COUNT(cat.car_no)   cat_count
                    FROM    DB2.dbo.z_cat       cat
                    WHERE   DATEDIFF(d, cat.notice_date, car.notice_date) = 0
                    AND     cat.branch_name     = brc.branch_name
                ) cat
CROSS APPLY     (   
                    SELECT  COUNT(pat.car_no)   pat_count
                    FROM    DB2.dbo.z_pat       pat
                    WHERE   DATEDIFF(d, pat.notice_date, car.notice_date) = 0
                    AND     pat.branch_name     = brc.branch_name
                ) pat
WHERE           car.notice_date > '2011-01-01'
GROUP BY        CONVERT(VARCHAR(10), car.notice_date, 120)
            ,   brc.branch_name

Answer 2

SELECT CONVERT(varchar(10),x.notice_date,120) Date,Y.branch_name,
COUNT(case when x.status='broken' then 1 end) Broken,
COUNT(case when x.type='Lote' then 1 end) Lost,
SUM(mat) mat, SUM(cat) cat,SUM(pat) pat
 FROM DB1.dbo.Cars x 
      JOIN DB2.dbo.Branch Y ON x.branch_name=y.branch_name
      -- group by date and branch name for z_mat table
      LEFT JOIN (select COUNT(car_no) mat,branch_name,DateAdd(Day, DateDiff(Day,notice_date), 0)) notice_date from DB2.dbo.z_mat GROUP BY branch_name,DateAdd(Day, DateDiff(Day,notice_date), 0)) AS a
          ON a.branch_name = y.branch_name AND DateAdd(Day, DateDiff(Day, 0,x.notice_date), 0) = a.notice_date
      -- group by date and branch name for z_cat table    
      LEFT JOIN (select COUNT(car_no) cat,branch_name,DateAdd(Day, DateDiff(Day,notice_date), 0)) notice_date from DB2.dbo.z_cat GROUP BY branch_name,DateAdd(Day, DateDiff(Day,notice_date), 0)) AS b
          ON b.branch_name = y.branch_name AND DateAdd(Day, DateDiff(Day, 0,x.notice_date), 0) = b.notice_date
      -- group by date and branch name for z_pat table        
     LEFT JOIN (select COUNT(car_no) pat,branch_name,DateAdd(Day, DateDiff(Day,notice_date), 0)) notice_date from DB2.dbo.z_pat GROUP BY branch_name,DateAdd(Day, DateDiff(Day,notice_date), 0)) AS c
          ON c.branch_name = y.branch_name AND DateAdd(Day, DateDiff(Day, 0,x.notice_date), 0) = c.notice_date 
WHERE DateAdd(Day, DateDiff(Day, 0,x.notice_date), 0)>'2011-01-01' 
GROUP BY CONVERT(varchar(10),x.notice_date,120),DateAdd(Day, DateDiff(Day, 0,x.notice_date), 0),y.branch_name