You are a database developer and you have about two years experience in creating business intelligence (BI) solutions by using SQL Server2008.

Now you are employed in a company which is named NaproStar and work as the technical support for the company which uses SQL Server2008. You are in charge of a SQL Server 2008 Reporting Services (SSRS) instance and you use it to create a report, which is so complex that it needs a few minutes to generate.
Now you are assigned a task to find a solution to configure the report server so that it can be cached for half an hour after the original request.

Which solution should be chosen to accomplish this task?

A.
The solution of using snapshot isolation to configure the data source would be chosen to accomplish this task

B.
The solution of using a database snapshot to configure the data source would be chosen to accomplish this task

C.
The solution of implementing report snapshots would be chosen to accomplish this task

D.
The solution of implementing report execution caching would be chosen to accomplish this task.

Explanation:

Using Report Caching
Reporting Services has two mechanisms to reduce the overhead associated with a large number of concurrent users, large datasets, and long-running queries: report caching and report snapshots. Report snapshots are reviewed in the next section.
By default, a report is rendered using the most recent data. This means that every execution starts by reading the database data. This could be a large processing burden on a production server. To reduce the load on your server, you can cache a temporary copy of a report. SSRS caches the report in the ReportServer database with all the data but without any of the rendering information. If a report exists in the cache, when the next user runs the report, the user gets the data from the cache, and there is no need to reread data from the database. Because the rendering information is not stored in the cache, a user can use any rendering format on the data. The data in the cache might become outdated after time, so you can define an expiration period for the cached report. You can define an expiration time in minutes, or you can force expiration on a shared or report-specific schedule.

The Execution properties are grouped by caching options, report execution snapshot, and report execution time-out.
After caching is enabled and the report is run for the first time after you enabled caching, the server stores the report data, and you can specify when the cache expires in one of two ways. First, the cache can be invalidated by specifying a number of minutes for which the cache is valid or by defining a report-specific schedule, or second, the cache can be invalidated through a shared schedule. The cache of a report will also be invalid if the data source credentials are changed or no longer stored on the report server.
To enable caching for a report, you can choose the Expire Copy Of Report After A Number Of Minutes option and set the expiration minutes. Alternatively, you can choose the Expire Copy Of Report On The Following Schedule option and then select the Report-Specific.

If you cache a report, the first user who runs the report after the cache has expired will have to wait longer to view the report than the users who follow, because the fi rst user triggers the data being read from the database.