Adam Machanic created an item on connect explaining how LINQ to SQL queries involving strings cause SQL Server procedure cache bloat

If an application is using LINQ to SQL and the queries involve the use of strings that can be highly variable in length, the SQL Server procedure cache will become bloated with one version of the query for every possible string length. For example, consider the following very simple queries created against the Person.AddressTypes table in the AdventureWorks2008 database:

If both of these queries are run, we will see two entries in the SQL Server procedure cache: One bound with an NVARCHAR(7), and the other with an NVARCHAR(11). Now imagine if there were hundreds or thousands of different input strings, all with different lengths. The procedure cache would become unnecessarily filled with all sorts of different plans for the exact same query. Even worse, imagine if a query used two or three different string parameters. The procedure cache could end up with hundreds of thousands or even millions of entries, the only differences being the variable lengths

Wow that is bad indeed, please go to the connect site and vote for this so that Microsoft ‘fixes’ this. Here is the URL: https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=363290

Dinesh wrote a blogpost about .NET Framework 3.5 SP1: LINQ perf improvements (LINQ to Objects and LINQ to SQL). There are three perf improvements in the just released SP1

Specialized enumerable: The new implementation recognizes queries that apply Where and/or Select to arrays or List<T>s and fold pipelines of multiple enumerable objects into single specialized enumerables. This produces substantial improvement in base overhead of common LINQ to Objects queries (at times 30+%).

Make sure to check it out!

Channel 9 has two screencast that deal with the new geography data type in SQL Server 2008.

Saving Virtual Earth Polygons to SQL Server 2008

Marc Schweigert shows you how to draw a polygon on a Virtual Earth map and save it using ASP.NET AJAX, Windows Communication Foundation (WCF), LINQ to SQL, and the new geography data type in SQL Server 2008.

Rendering Polygons from SQL Server 2008 on Virtual Earth

Marc Schweigert builds off of the concepts shown in his previous screencast and shows you how to render a polygon on a Virtual Earth map using REST, Windows Communication Foundation (WCF), LINQ to SQL, and the new geography data type in SQL Server 2008.

Enjoy the shows, and to learn more about the GeoRSS utility library, visit:
http://blogs.msdn.com/eugeniop/archive/2008/07/01/simple-georss-utility-library-released.aspx