Hello Pendry,

You can see those files in our WebGrid sample>>App_Code>>dsNorthwind_extended.cs.
The sample that used that method is ClassicPagingUsingCustomDataRetrieval.aspx.

Let's me explain the behaviour and logic in this code snippet.

1. Here is the first load.

At first, startRowIndex would start from 0 and maximumRows would start from 25.
In this case, startRowIndex and maximumRows are handled automatically by WebGrid.
In this sample, the paging size is left as default, which is 25. That's why maximumRows is 25.
startRowIndex starts from 0, means that WebGrid is still in page 1.
You can see the query details in the image.

2. Here is what hapenned if we navigate into the second page.

When you navigate into the second page (or maybe others page), startRowIndex would start from 25.
As I said before, WebGrid handled this automatically. The number page increased into 2 which would show the next startRowIndex based on your paging size.

3. If you do sorting during this scenario, you can also see that it will load based on your sortExpression which is also handled by WebGrid automatically.

For your information, all those paging are using ISDataSource.
If you don't want to use ISDataSource at all, you can your own query at InitializeDataSource event.
E.g in our WebGrid Tutorial>>V 3.5>>CustomVirtualLoad.aspx.
It is using VirtualLoad as its paging mode.

Regards,
Handy