mvc contrib pager question - AsPagination

Question

I might be wrong but is the AsPagination method not very inefficient as it sucks all the data from a repository first to initialise TotalItems etc.? So paging is not used to make the data access more efficient.

I have not found any examples which use a repository and 'true' paging (i.e. uses TOP etc. in the atcual SQL). How do I use the Pager if I have a repository method with this signature:

IList GetData(int? page, out int TotalItems)

Any feedback would be very much appreciated. Thanks.

Christian

Answer 1

You could use the CustomPagination<T> class which is part of MVCContrib like this:

public ActionResult Index(int page)
{
    int totalItems;
    int pageSize = 10;
    var data = Repository.GetData(page, out totalItems);
    var paginatedData = new CustomPagination<Bla>(
        data, page, pageSize, totalItems
    );
    return View(paginatedData);
}

and inside your view:

<%= Html.Pager(Model) %>

Answer 2

I think you may be misdirected with your assumptions on the paging efficiency? Try taking a look at the executing sql in profiler - it executes two sql statements - one to retrieve the count and one to select the top 10. Below is the results of the executed sql from profiler -

This sql retrieves gets the count - used by the pager:

SELECT [GroupBy1].[A1] AS [C1]
FROM ( SELECT 
   COUNT(1) AS [A1]
   FROM [dbo].[Customer] AS [Extent1]
)
AS [GroupBy1]

While the following is the sql used to retrieve the data:

SELECT TOP (10) 
[Extent1].[CustomerId] AS [CustomerId], 
[Extent1].[FirstName] AS [FirstName], 
[Extent1].[LastName] AS [LastName],
...
FROM ( SELECT [Extent1].[CustomerId] AS [CustomerId], [Extent1].[FirstName] AS [FirstName], [Extent1].[LastName] AS [LastName], ..., row_number() OVER (ORDER BY [Extent1].[Company] ASC) AS [row_number]
    FROM [dbo].[Customer] AS [Extent1]
)  AS [Extent1]
WHERE [Extent1].[row_number] > 20
ORDER BY [Extent1].[Company] ASC

Notice the TOP(10), row_number() over, and where ... > 20 statements in the second sql script? Does that help clarify?