The data for each metric is stored in a specific cache and, when the data is not updated in a certain period of time, that data either marked as expired or, if it has been expired over an extended period of time, it is deleted from the cache altogether.
Expire Time: This field sets the period of time when the Expire metric from the cache is set to true indicating the entry row is expired. The default expiration time is 45 seconds. The following caches are impacted by this field: JvmConnections, JvmGcInfo, JvmMemoryPool, JvmClassLoading, JvmCompilation, JvmOperatingSystem, JvmThreading, JvmMemory, JvmMemoryManager, JvmSystemProperties, RtvDataServerManager, RtvDisplayServerManager, RtvHistorianManager, RtvDataServerClientStats, RtvDataServerClientTotals, RtvServerVersion, TomcatWebModuleStats, TomcatConnectorInfo, TomcatGlobalRequestStats, TomcatHostInfo, and TomcatWebModuleTotals.
Delete Time: This field sets the period of time that a given entry row should be expired before it gets deleted from the cache. It defaults to 3600 seconds and applies to the following caches: JvmConnections, JvmGcInfo, JvmMemoryPool, JvmClassLoading, JvmCompilation, JvmOperatingSystem, JvmRuntime, JvmThreading, JvmMemory, JvmMemoryManager, JvmSystemProperties, RtvDataServerManager, RtvDisplayServerManager, TomcatWebModuleStats, TomcatGlobalRequestStats, TomcatWebModuleTotals, RtvHistorianManager, RtvDataServerClientStats, RtvDataServerClientTotals, RtvServerVersion, TomcatWebModuleStats, TomcatConnectorInfo, TomcatGlobalRequestStats, TomcatHostInfo and TomcatWebModuleTotals.