SQL Server表值功能性能

Question

我有一個5年的數據集分爲季度表。我也有一個主視圖，將它們連接在一起。當用戶需要超過四分之一的數據時，他們經常使用主視圖，而不是將多個小區連接在一起。

我的問題是，一個表值函數接受日期範圍，並只返回來自必要分區的記錄比查詢整個主視圖更快？

這是我當前視圖定義：

ALTER VIEW [dbo].[loandetails_test] 
AS 
SELECT  * 
FROM   loandetails05 
where year(date) = 2005 
UNION 
SELECT  * 
FROM   loandetails06 
where year(date) = 2006 
UNION 
SELECT  * 
FROM   loandetails07 
where year(date) = 2007 
UNION 
SELECT  * 
FROM   loandetails08 
where year(date) = 2008 
UNION 
SELECT  * 
FROM   loandetails1q09 
where date >= '1/1/2009' and date < '4/1/2009' 
UNION 
SELECT  * 
FROM   loandetails2q09 
where date >= '4/1/2009' and date < '7/1/2009' 
UNION 
SELECT  * 
FROM   loandetails3q09 
where date >= '7/1/2009' and date < '10/1/2009' 
UNION 
SELECT  * 
FROM   loandetails4q09 
where date >= '10/1/2009' and date < '1/1/2010' 
UNION 
SELECT  * 
FROM   loandetails1q10 
where date >= '1/1/2010' and date < '4/1/2010' 
UNION 
SELECT  * 
FROM   loandetails2q10 
where date >= '4/1/2010' and date < '7/1/2010' 
UNION 
SELECT  * 
FROM   loandetails3q10 
where date >= '7/1/2010' and date < '10/1/2010' 
UNION 
SELECT  * 
FROM   loandetails4q10 
where date >= '10/1/2010' and date < '1/1/2011' 
union 
SELECT  * 
FROM   loandetails_CURRENT 
where date >= '1/1/2011' and date < '4/1/2011' 


GO 

Answer 1

答案應該是堅實的沒有。

分區使用隱式標準進行設置，因此如果您按日期（季度）進行分區，SQL Server就會知道哪些分區將滿足查詢（假設查詢將具有日期過濾器）。檢查確認兩個（或涉及到的分區）之間的流合併的執行計劃。

我有一個情況，N個數據庫中的表（是每個筒倉一個）在主視圖中加入，就像您一樣。該master view使用爲每一個過濾器，特別是它看起來像這樣

select source=1, col1, col2, col3 
from db1.dbo.tbl 
union all 
select source=2, col1, col2, col3 
from db2.dbo.tbl 
etc 

，要求爲where source in (2,3)任何查詢自動識別，只有2 DBS需要進行搜索，並執行計劃顯示爲多。

如果是手動創建日期分區的查詢，可以

1. 對日期範圍的索引，每個表中
2. 力優化識別分區

這裏一個工作示例（即使沒有索引）。請注意，Q1和Q4甚至沒有在計劃中顯示。 披露：SQL Server 2008 R2的快速

select dateadd(d, number, '20100101') TheDate, * 
into Q1data 
from master..spt_values 
where type='p' and number between 1 and 370 
and datepart(quarter, dateadd(d, number, '20100101')) =1 

select dateadd(d, number, '20100101') TheDate, * 
into Q2data 
from master..spt_values 
where type='p' and number between 1 and 370 
and datepart(quarter, dateadd(d, number, '20100101')) =2 

select dateadd(d, number, '20100101') TheDate, * 
into Q3data 
from master..spt_values 
where type='p' and number between 1 and 370 
and datepart(quarter, dateadd(d, number, '20100101')) =3 

select dateadd(d, number, '20100101') TheDate, * 
into Q4data 
from master..spt_values 
where type='p' and number between 1 and 370 
and datepart(quarter, dateadd(d, number, '20100101')) =4 
GO 

create view Ydata 
with schemabinding 
as 
select TheDate, name, number, TYPE, LOW, high, status 
from dbo.Q1Data where TheDate >= '20100101' and TheDate < '20100401' 
union all 
select TheDate, name, number, TYPE, LOW, high, status 
from dbo.Q2Data where TheDate >= '20100401' and TheDate < '20100701' 
union all 
select TheDate, name, number, TYPE, LOW, high, status 
from dbo.Q3Data where TheDate >= '20100701' and TheDate < '20101001' 
union all 
select TheDate, name, number, TYPE, LOW, high, status 
from dbo.Q4Data where TheDate >= '20101001' and TheDate < '20110101' 
GO 

select * from YData where TheDate between '20100601' and '20100831' 

查詢計劃

回覆：更新問題

當日期範圍處理，NEVER（除少數例外）使用日期欄中的功能。這要求函數在與另一邊比較之前針對表中的所有記錄運行。

where year(date) = 2005 
===> means scan the table, for each row take the year, compare to 2005 

不如寫成

where date >= '20050101' and date < '20060101' 
===> means given a date range, use the index to seek the range