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Caching Data

[ Team LiB ] Recipe 9.3 Caching Data Problem Given a Web Forms application that is performing poorly because it is repeatedly reading data that doesn't change very often, you need to cache the data to eliminate unnecessary queries and improve the performance. Solution Use the ASP.NET Cache class. | Team LiB Recipe 9.3 Caching Data Problem Given a Web Forms application that is performing poorly because it is repeatedly reading data that doesn t change very often you need to cache the data to eliminate unnecessary queries and improve the performance. Solution Use the ASP.NET Cache class. The Web Forms page defines the data grid used to display the contents of a DataSet a button to clear the cache and a label that displays whether the data was retrieved from the cache or from the database. The code for the Web Forms page is shown in Example 9-3. Example 9-3. File ADOCookbookCS0903.aspx form id ADOCookbookCS0903 method post runat server asp HyperLink id HyperLink1 style Z-INDEX 101 LEFT 16px POSITION absolute TOP 24px runat server NavigateUrl default.aspx Main Menu asp HyperLink asp DataGrid id customersDataGrid style Z-INDEX 102 LEFT 16px POSITION absolute TOP 128px runat server AllowPaging True HeaderStyle Font-Bold True HeaderStyle asp DataGrid asp Label id cacheStatusLabel style Z-INDEX 103 LEFT 16px POSITION absolute TOP 96px runat server ForeColor Green asp Label asp Button id clearCacheButton style Z-INDEX 104 LEFT 16px POSITION absolute TOP 56px runat server Text Clear Cache asp Button form The code-behind contains three event handlers and two methods Page.Load Checks the cache for an object with the key CustomerDataSet. If an entry is not found the DataSet is loaded by calling the LoadDataSet method. If an entry is found the cached object is retrieved and cast to a DataSet. In either case the source of the data is displayed to the user. If the page is being loaded for the first time the CurrentPageIndex of the data grid on the page is set to 0 the first page and the BindDataGrid method is called to bind the default view of the Customers table to the data grid on the form. LoadDataSet This method loads a DataSet with the Customers table from the Northwind database. The DataSet is added to the cache with the key CustomerDataSet and an expiration time of .