When a user types a query into the search box of our price comparison website, we try to figure out what they search, and provide suggestions as they type along. What product, what brand, from which categories? Solr provides a SuggestComponent that is a good start, but in a lot of situations we need fallback strategies: what should we show to a user searching for just a brand name? Or for a singular offer we can't actually show them? What alternatives can we dig up? And behind all this backfill logic lurks that dreaded question: what amount of irrelevant garbage is worse than the horror vacui of an empty result set?