I am developing a web application in ASP.NET and on one page I am using a ListView with paging. As a test I populated the table it draws from with 6 million rows.
The table and a schema-bound view based off it have all the necessary indexes and executing the query in SQL Server Management Studio with SELECT TOP 5 returned in < 1 second as expected.
But on the ASP.NET page, with the same query, it seems to be selecting all 6 million rows without any limit. Shouldn’t the paging control limit the query to return only N rows rather than the entire data set? How can I use these ASP.NET controls to handle huge data sets with millions of records? Does SELECT [columns] FROM [tablename] quite literally mean that for the ListView, and it doesn’t actually inject a TOP <n> and does all the pagination at the application level rather than the database level?
When you enable paging, the paging control, datasource, grid, etc. will limit the number of rows displayed by the control. However, they definitely will not limit the number of rows returned by the SELECT statement.
You should be using DataObjectSource as the control’s data source and have it call a class method that executes a SELECT statement that only returns the necessary rows. Otherwise, your performance will be horrible.
Unfortunately, SQL Server doesn’t support any type of RANGE clause and the required SQL isn’t very pretty. But it is absolutely necessary.
http://www.asp.net/data-access/tutorials/efficiently-paging-through-large-amounts-of-data-cs