http://msdn.microsoft.com/en-us/library/ms181714.aspx
MAXDOP number
Overrides the max degree of parallelism configuration option of sp_configure and Resource Governor for the query specifying this option. The MAXDOP query hint can exceed the value configured with sp_configure. If MAXDOP exceeds the value configured with Resource Governor, the Database Engine uses the Resource Governor MAXDOP value, described in ALTER WORKLOAD GROUP (Transact-SQL). All semantic rules used with the max degree of parallelism configuration option are applicable when you use the MAXDOP query hint. For more information, see max degree of parallelism Option.
Caution note Caution
If MAXDOP is set to zero then the server chooses the max degree of parallelism.
Using MAXDOP
The following example uses the MAXDOP query hint.
Copy
USE AdventureWorks2008R2 ;
GO
SELECT ProductID, OrderQty, SUM(LineTotal) AS Total
FROM Sales.SalesOrderDetail
WHERE UnitPrice < $5.00
GROUP BY ProductID, OrderQty
ORDER BY ProductID, OrderQty
OPTION (MAXDOP 2);
GO
