title: WPF Datagrid: Lazy Loading / Inifinite scroll
body: <p>I fill the Datagrid with 250 rows. When the user scrolls down using the scrollbar (below 75% for example), I want to fetch the next 250 rows from the database, and so on. The idea is that the grid could have millions of results and we don't want to load them all, until the user requests them. Is there an existing mechanism for this?</p>
  
  <p>EDIT: Because there seem to be a lot of confusion: I'm not looking for the standard data virtualization solutions, I already use <a href="http://www.devzest.com/blog/post/WPF-Data-Virtualization.aspx" rel="noreferrer">them</a>. But they all require you to specify the number of 'virtual rows' in advance, and that query is to costly for me. The reason why they require it is because it's makes it so much easier to calculate the current page/offset/etc when you know the total items in the grid. But it is a very costly sql-query to calculate that amount, so I want to migrate to another solution where I can skip the COUNT() query.</p>