Data caching

You can configure data caching to improve dashboard performance.

Data caching is done through server-side caching and browser-side caching. Dashboards run only under Dynamic Query Mode (DQM), which means that even for supported Compatible Query Mode (CQM) data sources, Cognos® Analytics converts data sources at run time to run in the DQM infrastructure. For relational database sources, you must configure Cognos Analytics to connect to the data source through a JDBC driver.

If a dashboard does not present data in real time each time you open the dashboard, you might need to perform one of the following:

Server-side caching

Server caching stores result sets from dashboard queries on the Cognos Analytics servers for reuse if the following requirements are met:

  • The users that run the queries match the same or compatible query pattern.
  • The security profile and data source connection profile both match. That is, the user has permission to access the same data source connection, and sign-on information that is configured for the data source and the data security that is defined in the model matches.

Storing result sets like this improves performance and makes sure that the data is secure.

Server caching works with the data cache configuration that is specified by the modeler in a Framework Manager model or in a data module. By default, the cache behavior for a new dashboard is set to Automatic, which means that the dashboard uses the model's default setting for caching. You can override this default behavior in the dashboard by changing its configuration. For more information about configuring a dashboard's server-side cache behavior, see Enabling server-side data caching.

In Framework Manager, you can configure the default cache behavior in the project governors with the Allow usage of local cache property. For DQM models, you can configure a query subject's properties in further detail using the (DQM) Use local cache property. For more information about setting up caching in a data module, see Enabling data caching.

Note: If you have large dashboards that use data sources with a configured server-side cache, you can increase the DQM cache side to improve performance. While you cannot configure DQM from the dashboard, you can change the DQM cache size from the Administration console. Increasing the cache size allows the DQM to handle more concurrent queries, but increases resource usage. For more information, see Changing the cache size of dynamic queries

Browser-side caching

Browser-side caching operates independently of the server-side DQM cache. Configure browser-side caching by using the Configure local cache property in Advanced properties of each dashboard. Browser-side caching uses the web browser to store query data on the client side to improve performance, which mitigates the need to go back to the data source or to the DQM server-side cache, if it exists. Browser-side caching uses the browser to store data on the client. When browser-side caching is enabled, the client application stores query results in the local browser. Storing the query results eliminates network traffic and server processing time. Each time that you open the dashboard, the dashboard retrieves information from Cognos Analytics and caches this data on the browser side. As you interact with the dashboard, the dashboard uses the cache while your actions do not require the dashboard to retrieve more data from the data sources. The cache is only active during the dashboard session.

Note: Browser-side caching is not available in Cognos Analytics reports.

You can also configure and refine specific data caches and data elements within those caches. If your query requirements are not in the configured browser-side caches, the dashboard sends the query to the Cognos Analytics server and retrieves the data from either the data source or a DQM cache, if it exists.

When a browser-side cache definition changes and the data are not already in the cache, the dashboard retrieves the data again and caches the data on the Save operation if you turned on the Auto-generate on save property. You can also manually reload a cache. For more information, see Specifying data elements for browser-side caching.