Indexing technologies tend to have support for facets https://en.wikipedia.org/wiki/Faceted_search https://en.wikipedia.org/wiki/Faceted_search generally what

Indexing technologies tend to have support for facets https://en.wikipedia.org/wiki/Faceted_search https://en.wikipedia.org/wiki/Faceted_search generally what you have is lightweight searches that you can query and get just the count of documents you would receive, in the case of facets you can generally get a list of facets or even a list of facets relating to a particular search and a count for each of these facets.