SQL Server 2012提供的OFFSET/FETCH NEXT与Row_Number()对比测试

原文连接：http://www.cnblogs.com/downmoon/archive/2012/04/19/2456451.html

在《SQL Server 2012服务端使用OFFSET/FETCH NEXT实现分页》一文中，我引用了《SQL Server 2012 - Server side paging demo using OFFSET/FETCH NEXT》，原文地址：

http://beyondrelational.com/modules/29/presentations/483/scripts/12983/sql-server-2012-server-side-paging-demo-using-offsetfetch-next.aspx?utm_source=brnewsletter&utm_medium=email&utm_campaign=2012Apr，作者在文中称，要SQL Server 2012使用OFFSET/FETCH NEXT分页，比SQL Server 2005/2008中的RowNumber()有显著改进。今天特地作了简单测试。现将过程分享如下：

沿用上文的测试数据库和表：

IF OBJECT_ID('DemoPager2012') IS NOT NULL
DROP DataBase DemoPager2012
GO
CREATE Database DemoPager2012
GO
USE DemoPager2012
GO
/*
Setup script to create the sample table and fill it with
sample data.
*/
IF OBJECT_ID('Customers','U') IS NOT NULL
DROP TABLE Customers

CREATE TABLE Customers ( CustomerID INT primary key identity(1,1),
CustomerNumber CHAR(4),
CustomerName VARCHAR(50),
CustomerCity VARCHAR(20) )
GO

TRUNCATE table Customers
GO

DBCC DROPCLEANBUFFERS
DBCC FREEPROCCACHE

/*****运用CTE递归插入，速度较快，邀月注***********************/
WITH Seq (num,CustomerNumber, CustomerName, CustomerCity) AS
(SELECT 1,cast('0000'as CHAR(4)),cast('Customer 0' AS NVARCHAR(50)),cast('X-City' as NVARCHAR(20))
UNION ALL
SELECT num + 1,Cast(REPLACE(STR(num, 4), ' ', '0') AS CHAR(4)),
cast('Customer ' + STR(num,6) AS NVARCHAR(50)),
cast(CHAR(65 + (num % 26)) + '-City' AS NVARCHAR(20))
FROM Seq
WHERE num <= 10000
)
INSERT INTO Customers (CustomerNumber, CustomerName, CustomerCity)
SELECT CustomerNumber, CustomerName, CustomerCity
FROM Seq
OPTION (MAXRECURSION 0)

插入1万条数据后，在SQL Server 2008 R2中执行Row_Number()：

/*
Server side paging demo using ROW_NUMBER() - SQL Server
2005/2008 version.
*/

DBCC DROPCLEANBUFFERS
DBCC FREEPROCCACHE

SET STATISTICS IO ON;
SET STATISTICS TIME ON;
GO

DECLARE @page INT, @size INT
SELECT @page = 3, @size = 10

;WITH cte AS (
SELECT TOP (@page * @size)
CustomerID,
CustomerName,
CustomerCity,
ROW_NUMBER() OVER(ORDER BY CustomerName ) AS Seq,
COUNT(*) OVER(PARTITION BY '') AS Total
FROM Customers
WHERE CustomerCity IN ('A-City','B-City')
ORDER BY CustomerName ASC
)
SELECT * FROM cte
WHERE seq BETWEEN (@page - 1 ) * @size + 1 AND @page * @size
ORDER BY seq;
GO

SET STATISTICS IO OFF ;
SET STATISTICS TIME OFF;
GO

SQL Server 2012中执行OFFSET/FETCH NEXT语句如下：

/*
Server side paging demo using the new enhancements added
in SQL Server 2012
*/
DBCC DROPCLEANBUFFERS
DBCC FREEPROCCACHE

SET STATISTICS IO ON;
SET STATISTICS TIME ON;
GO

DECLARE @page INT, @size INT
SELECT @page = 3, @size = 10

SELECT
*,
COUNT(*) OVER(PARTITION BY '') AS Total
FROM Customers
WHERE CustomerCity IN ('A-City','B-City')
ORDER BY CustomerID
OFFSET (@page -1) * @size ROWS
FETCH NEXT @size ROWS ONLY;
GO

SET STATISTICS IO OFF;
SET STATISTICS TIME OFF;
GO

在SQL Server 2012中执行如下语句：

DBCC DROPCLEANBUFFERS
DBCC FREEPROCCACHE

SET STATISTICS IO ON;
SET STATISTICS TIME ON;
GO

DECLARE @page INT, @size INT
SELECT @page = 3, @size = 10

;WITH cte AS (
SELECT TOP (@page * @size)
CustomerID,
CustomerName,
CustomerCity,
ROW_NUMBER() OVER(ORDER BY CustomerName ) AS Seq,
COUNT(*) OVER(PARTITION BY '') AS Total
FROM Customers
WHERE CustomerCity IN ('A-City','B-City')
ORDER BY CustomerName ASC
)
SELECT * FROM cte
WHERE seq BETWEEN (@page - 1 ) * @size + 1 AND @page * @size
ORDER BY seq;

SELECT
*,
COUNT(*) OVER(PARTITION BY '') AS Total
FROM Customers
WHERE CustomerCity IN ('A-City','B-City')
ORDER BY CustomerID
OFFSET (@page -1) * @size ROWS
FETCH NEXT @size ROWS ONLY;
GO

SET STATISTICS IO OFF;
SET STATISTICS TIME OFF;
GO

结果：

结论：无论是从逻辑读取数还是响应时间、实际执行行数等关键参数看，SQL Server 2012提供的OFFSET/FETCH NEXT分页方式都比Row_Number()方式有了较大的提升。

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