LINQ in .NET Compact Framework 3.5 Webcast

Uh, could you point me to some resources explaining where and why DataSets have bad performance? I have not heard of that before, and I am using DataSets all over my app currently. Thanks.

Timo;

On the desktop, I have little concern about DataSets. My concern is specific to apps running on mobile devices. Even then, my intent is not to say that DataSets are universally bad in mobile applications; if they're working for you with acceptable performance and memory consumption there's no reason to change.

The issues with DataSets begin to occur as one's data volume grows. When data is stored in a SSC database, populating a DataSet duplicates that data in local storage when the data is already locally available and therefore consumes memory that can be used for something else; many mobile app databases won't even fit in memory as a DataSet - in fact, I've worked on many apps where the SSC database won't even fit on the device directly but must rather be stored on a memory card.

In almost all cases, one can query a SSC database and retrieve the data in less time than it takes to populate a DataSet. DataSets don't have indexes so if you need to frequently query your data, you don't get the performance benefit that SSC (or any other db) provides when using an index in a query. Again, matters most in large data volumes.

So when I say DataSets are problematic, I should probably qualify that statement to say that they're problematic when dealing with significant data volumes. For me though, in most of the mobile apps I do/have work the data volumes eventually grow to a point where DataSets become problematic. As a result, I encourage people to consider working with SSC directly when they can. But this is my experience - you mileage may vary ... so to speak. :-)

Ah, I see. Thanks.

Timo;

BTW - I encourage you to checkout today's webcast. As part of the presentation, I'll show some hard numbers gathered with the CLR profiler that show how DataSets compare to querying SSC directly - will give you an accurate picture of increase in memory consumption, garbage collections, etc.

I hope to see you there.

Jim

Would appreciate seeing that stats bmp you mention in the vid.

Will check back every once in a while to see if you've uploaded it.

Tristan;

I think you'll find what you're looking for on the post I put up following the webcast - http://www.pluralsight.com/blogs/jimw/archive/2008/02/27/50325.aspx

Let me know if that's not what you're looking for.

- Jim