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Request faster with top attribute

Why is this query faster in SQL Server 2008 R2 (version 10.50.2806.0)

    SELECT
        MAX(AtDate1),
        MIN(AtDate2)
    FROM
    (
        SELECT TOP 1000000000000
            at.Date1 AS AtDate1,
            at.Date2 AS AtDate2
        FROM
            dbo.tab1 a
        INNER JOIN
            dbo.tab2 at
        ON
            a.id = at.RootId
        AND CAST(GETDATE() AS DATE) BETWEEN at.Date1 AND at.Date2
        WHERE
            a.Number = 223889
    )B

then

    SELECT
        MAX(AtDate1),
        MIN(AtDate2)
    FROM
    (
        SELECT 
            at.Date1 AS AtDate1,
            at.Date2 AS AtDate2
        FROM
            dbo.tab1 a
        INNER JOIN
            dbo.tab2 at
        ON
            a.id = at.RootId
        AND CAST(GETDATE() AS DATE) BETWEEN at.Date1 AND at.Date2
        WHERE
            a.Number = 223889
    )B

?

The second statement with an attribute TOPis six times faster.

count(*) The internal subquery is 9280 rows.

Can TIP be used to declare that SQL Server Optimizer is doing it right? execution plan

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2 answers

I see that you have now posted plans . Just a draw in luck.

Your actual query is a 16 table join.

SELECT max(atDate1)  AS AtDate1,
       min(atDate2)  AS AtDate2,
       max(vtDate1)  AS vtDate1,
       min(vtDate2)  AS vtDate2,
       max(bgtDate1) AS bgtDate1,
       min(bgtDate2) AS bgtDate2,
       max(lftDate1) AS lftDate1,
       min(lftDate2) AS lftDate2,
       max(lgtDate1) AS lgtDate1,
       min(lgtDate2) AS lgtDate2,
       max(bltDate1) AS bltDate1,
       min(bltDate2) AS bltDate2
FROM   (SELECT TOP 100000 at.Date1  AS atDate1,
                          at.Date2  AS atDate2,
                          vt.Date1  AS vtDate1,
                          vt.Date2  AS vtDate2,
                          bgt.Date1 AS bgtDate1,
                          bgt.Date2 AS bgtDate2,
                          lft.Date1 AS lftDate1,
                          lft.Date2 AS lftDate2,
                          lgt.Date1 AS lgtDate1,
                          lgt.Date2 AS lgtDate2,
                          blt.Date1 AS bltDate1,
                          blt.Date2 AS bltDate2
        FROM   dbo.Tab1 a
               INNER JOIN dbo.Tab2 at
                 ON a.id = at.Tab1Id
                    AND cast(Getdate() AS DATE) BETWEEN at.Date1 AND at.Date2
               INNER JOIN dbo.Tab5 v
                 ON v.Tab1Id = a.Id
               INNER JOIN dbo.Tab16 g
                 ON g.Tab5Id = v.Id
               INNER JOIN dbo.Tab3 vt
                 ON v.id = vt.Tab5Id
                    AND cast(Getdate() AS DATE) BETWEEN vt.Date1 AND vt.Date2
               LEFT OUTER JOIN dbo.Tab4 vk
                 ON v.id = vk.Tab5Id
               LEFT OUTER JOIN dbo.VerkaufsTab3 vkt
                 ON vk.id = vkt.Tab4Id
               LEFT OUTER JOIN dbo.Plu p
                 ON p.Tab4Id = vk.Id
               LEFT OUTER JOIN dbo.Tab15 bg
                 ON bg.Tab5Id = v.Id
               LEFT OUTER JOIN dbo.Tab7 bgt
                 ON bgt.Tab15Id = bg.Id
                    AND cast(Getdate() AS DATE) BETWEEN bgt.Date1 AND bgt.Date2
               LEFT OUTER JOIN dbo.Tab11 b
                 ON b.Tab15Id = bg.Id
               LEFT OUTER JOIN dbo.Tab14 lf
                 ON lf.Id = b.Id
               LEFT OUTER JOIN dbo.Tab8 lft
                 ON lft.Tab14Id = lf.Id
                    AND cast(Getdate() AS DATE) BETWEEN lft.Date1 AND lft.Date2
               LEFT OUTER JOIN dbo.Tab13 lg
                 ON lg.Id = b.Id
               LEFT OUTER JOIN dbo.Tab9 lgt
                 ON lgt.Tab13Id = lg.Id
                    AND cast(Getdate() AS DATE) BETWEEN lgt.Date1 AND lgt.Date2
               LEFT OUTER JOIN dbo.Tab10 bl
                 ON bl.Tab11Id = b.Id
               LEFT OUTER JOIN dbo.Tab6 blt
                 ON blt.Tab10Id = bl.Id
                    AND cast(Getdate() AS DATE) BETWEEN blt.Date1 AND blt.Date2
        WHERE  a.Nummer = 223889) B

In both good and bad plans, the execution plan shows “Reason for early termination of operator optimization” as “Timeout”.

Two plans include several different connection orders.

, , - Tab9. 63 926 .

, .

CREATE NONCLUSTERED INDEX [miising_index]
ON [dbo].[Tab9] ([Date1],[Date2])
INCLUDE ([Tab13Id])

SQL Sentry Plan Explorer

Bad plan

SQL Server , 1.349174 , Tab9. , , , 1.349174 .

2600 , , 2600 Tab9 (2600 * 63 926 = 164 569 600 ).

, , , 2.74319. , , SQL Server -. Tab9

Good plan

Tab9.

, ( , Tab2 Tab3 Tab7 Tab8 Tab6), , - .

. SQL Server .

, , -. - USE PLAN, , , , LEFT OUTER HASH JOIN tab9 .... . , SQL Server , .

+3

, , . Hash Match "top n" vs Nested Loop . Hash Match - , -, . , Nested Loops, ​​ , , . , , TOP 1000000000000 , , , Hash Match. , Nested Loops . , , , , , ;).

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