Search API Filter Facet

A facet filter allows to return a count of the hits matching the facet filter. The filter itself can be expressed using the Query DSL. For example:

{
    "facets" : {
        "wow_facet" : {
            "filter" : {
                "term" : { "tag" : "wow" }
            }
        }
    }
}    

Note, facet filters are faster than query facet when using native filters (non query wrapper ones).