We're using Views to display our search_api_solr results. We'd like to be able to show these results by radioactivity (popularity) sort order.
The radioactivity field is one of several fields indexed by Solr so that it can be used by the Solr views for sorting.
The problem is, the radioactivity value that gets indexed by solr only gets updated when the entity gets indexed. The entity only gets indexed when it gets changed (node_update), or when the Solr index is cleared and everything is reindexed again. Having an entities radioactivity energy adjusted by visiting the entity, does not trigger solr to reindex the entity - and probably rightly so.
I've tried adding a relationship in the Search View to node, but that isn't available as a "search index" view type.
Does anyone have any other suggestions for solving this? There doesn't seem to be a radioactivity hook that lets you execute your own code, i.e. update search_api_item table to say its changed.