Configuring Data Source Caching


The DTV data source acts as a data display channel and provides caching of data to coordinate the performance of the back-end interface data queries with the performance of the front-end page display.


 Caching is when a user queries a piece of data and then stores that data for a certain amount of time. If the user queries the same data again before the cache is cleared, the DTV will read the data from the cache instead of reading it from the data source. When the set cache time is exceeded, the cache is cleared and the next time the user queries for the same data, the DTV will read the data from the data source and generate a new cache to store for a certain amount of time.


Depending on the user’s needs for data usage, you can set separate cache cleaning times for data sources, or you can manually clear the cache when needed.

For example

  • When a user requires data from a data source to be real-time, the data source may not be set for a cache clear time and the DTV will not cache the data source. Whenever the user requests data from the data source, the data will be read in real-time. As the data is read in real-time every time it is used, it will take a relatively long time to retrieve the data.
  • When a user requires a high level of real-time data from a data source, but also requires that the data does not take a long time to retrieve, a short cache clear time can be set for that data source and the DTV will clear the cache after a short period. When the user repeatedly queries the same data in a short period, the data will be read faster.
  • When a user requires a low level of real-time data from a data source and a short time to fetch the data, a long cache clear time can be set for the data source and the DTV will clear the cache after a longer period. When the user queries the same data repeatedly over a long period, the data will be read faster, but the data will be less reliable. In this case, if the user wishes to re-read the data, the cache can be cleared manually.


DTV stores the following types of cache for all data sources (except Static Data):

  • Metadata: Data that provides information about your data source. This refers to all field information involved in the configuration of the data source by the user, such as table headers, measurement points, indicators, attributes, etc. of the data source. The metadata cache is only available in the edit mode and can be turned on to avoid too much lag when configuring pages.
  • Data: Actual values of data retrieved. This refers to all the real data displayed in the widgets after they have been configured by the user. The caching of data is enabled in both the edit and run modes to avoid lagging when configuring pages and displaying pages.


Clearing Cache Periodically


Set the auto-clear cache time and DTV will automatically clear the cache after the set time.


You can set how frequently the cache will be cleared by following these steps:

  1. In the Dashboard Editor, select Data Source from the Navigation Pane.
  2. Locate the data source in their respective tabs.
  3. Hover over the ellipsis (…).
  4. Select Edit.
  5. In the Metadata Cache box, specify how frequently DTV should clear the meta cache.
  6. In the Data Cache box, specify how frequently DTV should clear the data cache.
  7. Select OK.

Clearing Cache Manually


Alternatively, you can clear the cache manually (data and meta) by following these steps:

  1. In the Dashboard Editor, select Data Source from the Navigation Pane.
  2. Locate the data source in their respective tabs.
  3. Hover over the ellipsis (…).
  4. If you want to clear the meta cache, select Clear Meta Cache.
  5. If you want to clear the data cache, select Clear Data Cache.