[11] Caching

Panopticon Real Time supports five levels of caching:

q  Data extracts, offline and manually created

q  Real-time subscription cache

q  Data source cache

q  Data table cache

q  Query result cache

All of which are optional.  If caching is specifically not desired, data requests can always be forwarded to the underlying data repository.

The subscription cache describes the cache used for streaming subscriptions.  This cache is used to ensure subscriptions are not duplicated by the server, and that instead the Server manages duplicate end client subscription requests.  Subscriptions are started when the server receives a valid client request and can be set to stop when users are no longer watching data from them or be kept alive until the server is stopped..

The data caches simply keep corresponding data sources and tables in memory to avoid unnessary reloads from the underlying data repositories. Neither is used for real-time data, but the data source cache helps with real-time data is joined to standing data. The cache entries are keyed on:

q  The workbook

q  The data table

q  (The data source)

q  Parameter values

The time-to-live (TTL) for entries is based on the auto refresh period set on the data table.

The query result cache stores the result of a query from an individual visualization, filter, or legend on a dashboard. It is useful if many users are viewing the same dashboard, when many identical queries will be sent in parallel to the server. It also caches real-time data for this purpose.