By default, dashboard servers (Data Servers and Display Servers) collect trend data for all numeric output variables of scenarios and data views running in their associated correlators. This data is cached in preparation for the possibility that it will be displayed as historical data in a trend chart when a dashboard starts up. Without the cache, trend charts would initially be empty, with new data points displaying as time elapses.

Advanced users can override the default caching behavior on a given server, and control caching in order to reduce memory consumption on that server, or in order to cache variables that are not cached by default, such as non-numeric variables.

For more information, see Controlling Trend-Data Caching in Deploying and Managing Apama Applications for more information.