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70-562 Data Caching


If the data is control by other services, it can be delicate to cache.

Data can be cached and automaticaly updated when sql changes.

It depends on sql 2005 and later Query Notification, previous versions relies on database triggers.

ASP.Net can poll changes to the table, and sql can be configureged with Aspnet_regsql tool.

The the target table has to be configured with the aspnet_regsql tool, a changed id is added to the table.

Polls based caching is very reliable and easy to configure.


Datasource controls have properties to enable caching, this also requires the table to be configured with the aspreg tool.

Table caching caches only tables, not the page.

Can also be based on rows, to change only when specific row changes, for example products of a certain category. It will update only when this row is changed, this is custom caching rules.


QueryNotification caching doesnt require to configure sql. The service broker has to be enabled. Alter database northwind set service broker. Query notification also works in sql express.
A channel has to be created in teh glorbal.asax in the start you start SqlDependency.Start, and the opposite in stop.

QueryNotification can't use aggregates, image columns, cant use non detemrinistic functions like get date, cant use distinct, full name like dbo.tableName, no * in select have to be explicit with culumn names.

To use the datasource, use sqlcommandnotification as an attribute of the datasource, and this can be confugred from code, using SqlCAcheDependency.

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