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The cache is a "temporary storage place" on the Forsta Plus servers. When report pages are generated, the pages are stored in the cache so that new visitors can view the cached pages without them having to be regenerated. Using this method, the servers do not have to re-calculate the numbers in the SQL database, thus saving waiting time for report pages to load - hence also for our servers.
To improve the performance of the report for the viewers, you can specify for how long the report pages are to be stored in the cache. When a cached report page is opened for a report viewer, the report engine will not query the database to build an updated table and chart, but use the results that are stored on the server. Consequently the report page will load much faster, giving your viewers a better user experience.
The tab is as shown belowshow me.
Figure 1 - The Report Properties > Cache Settings tab
The properties on this tab are as follows:
- Expire Rate Unit – specify for how long the report pages should be stored in the cache before being updated.
- Never - the cache will never expire.
- Weeks - the cache will expire X weeks after it was last rebuilt.
- Days - the cache will expire X days after it was last rebuilt.
- Hours - the cache will expire X hours after it was last rebuilt.
- Expire Rate N - specify the number of units (integer) selected in the previous property, that are to be used.
When a viewer accesses a page, Reportal will check if the expiry time has passed, and if it has it will rebuild the report page. If not, the page will be retrieved from the cache. In Reportal the charts and tables are updated when a viewer or designer accesses the report. If nobody accesses the report for 24 hours then it will not be updated, even though the cache settings specify 1 hour. If the project is closed and interviewing is finished, there should be no reason for selecting anything but “Never Expire”, as this will give your Report Viewers the best user experience. The other options can be chosen when the survey is live to give your viewers updated results.
The update will be done regardless of whether any changes have been made in the database; the only thing it checks for is the cache expiry date/time. If your report is based on BitStream files, the cache will automatically be cleared if the BitStream file set is updated.
To force Reportal to clear the cache on a report, go to the Report > Update > Clear Cache menu command.