Help:$smwgQueryResultCacheRefreshOnPurge

is a configuration parameter that sets whether it is possible to manually refresh the query cache by doing a "purge" action. It was introduced in Semantic MediaWiki 2.5.0.CiteRef::gh:smw:1251

Default setting
This means that by default purging the query cache is allowed.

Changing the default setting
To modify the setting to this configuration parameter, add one of the following lines to your "LocalSettings.php" file after the  call:

This means that purging the query cache is not allowed. The wiki will then retain the cache of embedded queries and their results fetched from the query engine.
 * Disable manual purging of the cache