Dataadapter update performance - do I need to use datatable.Getchanges?

Question

This is a simple question, but I'm having trouble finding the answer.

I have a large datatable of which I have updated many, but not all rows.

I am using a dataadapter to update these changes to SQL server.

Does the dataadapter send update queries only for the updated rows from the datatable, or does it send one for every row, and escentialy tell SQL server to run a pointless update?

I'm wondering which of these two methods would be more appropiate for minimizing the load on the SQL server:

dataadapter.update(datatable)

dataadapter.update(datatable.getChanges(DataRowState.Modified))