Reporting Service (SSRS) 2008 R2 allows us to execute reports in 3 modes:

1. On Demand
2. From Cache
3. From Snapshots

On Demand

• This is normal approach that we follow, by hitting a report server URL. Each time a report is run, data is returned from the database server and rendered to the report.
• This approach ensures that our report is update and fresh.
• The downside of this approach is that, if n users open up this report on their browsers, queries on the report are executed n times.
• Thus this approach at times might slow down the server.

Cache

• One of the performance enhancements techniques is to cache a report when it is initially run.
• This means that if another user requests for the report, the same report is served to the user from the cache.
• This avoids people querying the database server from each report rendering.
• To make sure that people do not receive too much stale data, we can set a time to invalidate a cache.
• This is a good performance enhancement technique for slow running reports.

Snapshots

• Report snapshots are created at a particular schedule for certain parameters.
• Please note that parameters cannot be changes on snapshot reports.
• SSRS 2008 R2 allows to schedule the snapshot creation times.
• Users can directly render a report from a snapshot. However please note that not all reports can have snapshots, especially the ones that prompt users for credentials.