Sunday, February 24, 2008

SQL SERVER – Paging Query Technique

I decided to checkout new function ROW_NUMBER() in SQL Server 2005. ROW_NUMBER() returns the sequential number of a row within a partition of a result set, starting at 1 for the first row in each partition. I have compared both the following query on SQL Server 2005.

SQL 2005 Paging Method

SQL 2005 Paging Method Using Derived Table

USE AdventureWorks

GO
DECLARE @StartRow INT
DECLARE @EndRow INT
SET @StartRow = 120
SET @EndRow = 140

SELECT FirstName, LastName, EmailAddress
FROM (
SELECT PC.FirstName, PC.LastName, PC.EmailAddress,
ROW_NUMBER() OVER(
ORDER BY PC.FirstName, PC.LastName,PC.ContactID) AS RowNumber
FROM Person.Contact PC) PersonContact
WHERE RowNumber > @StartRow
AND RowNumber < @EndRow
ORDER BY FirstName, LastName, EmailAddress
GO

SQL 2005 Paging Method Using CTE

USE AdventureWorks

GO
DECLARE @StartRow INT
DECLARE @EndRow INT
SET @StartRow = 120;
SET @EndRow = 140;
WITH PersonContact AS
(
SELECT PC.FirstName, PC.LastName, PC.EmailAddress,
ROW_NUMBER() OVER(
ORDER BY PC.FirstName, PC.LastName,PC.ContactID) AS RowNumber
FROM Person.Contact PC)
SELECT FirstName, LastName, EmailAddress
FROM PersonContact
WHERE RowNumber > @StartRow
AND RowNumber < @EndRow
ORDER BY FirstName, LastName, EmailAddress
GO








Above Image of Execution Plan displays that the performance for both of them is same with regarding to each other in one batch. This MAY NOT be true when there is complex query in issue. For most of the time, it is will be same.

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