Within CirrusSearch we need the ability to turn some settings on/off based on the language of the wiki. The most recent example is that the per-field bm25 query builder we are using doesn't seem to work particularly well on languages without spaces between their words (zh, ja, and several more). We would like to still ship this feature out to most languages, where it has tested to be an improvement over the previous implementation, but continue serving the query-string query based implementation to languages where it is not an improvement.

We could of course list out all the wiki's that use the language, but that would be tedious, error prone, and overly verbose. Instead add a 'wikiTag', per SiteConfiguration::get, that allows defining settings based on the language of the wiki in question.