Dataset.Clear() Doesn't Mark Rows As Deleted

Ok, I've spent a good amount on time on debugging an unupdating scenario in my application. Finally I knew the reason which is very annoying. Either I'm missing something really obvious (I hope so,) or this is a bug.

to reproduce what I'm talking about:
1- create a new win forms application using VS2005 sp1
2- add some SQL Compact Edition data file that have some records from the data menu, you'll get the designer to generate the dataset and everything..
3- drag a table from the data sources window, you'll get the data grid and the navigator on the form
4- add a button and have this in the click event handler:
datasetname.Clear();
TableAdapterName.Update(datasetname);

launch the program, click the button, you'll see the grid get wiped out as it supposed to do. close the program and relaunch. the data is there again (this has nothing to do with the copy always, copy if newer infamous stupidity)

now:
5- edit the click event handler and change it so something like this:
foreach (datasetname.TableRow row in datasetname.Table)
{
row.Delete();
}
TableAdapterName.Update(datasetname);

Launch the program, hit the button, grid wiped out. exit and relaunch. You'll see no data (i.e. the update on table adapter worked alright)

You can also try the GetChanges method on the dataset rightafter you use the clear method and you'd get no deleted records at all.

So, in 100,000+ records dataset, if i need to wipe the thing out and add some new records do i have to loop over every record and call delete (which will take LOTS of time).
I do hope that I'm missing something obvious.

Any help would be highly appreciated.

Thanks.