: Unfortunately which strategy will be chosen is currently undocumented : and control is a bit oblique: If the field is tokenized or multivalued : or Boolean, the FilterQuery method will be used; otherwise the : FieldCache method. I expect I or others will improve that shortly.
Bear in mind, what's provide out of the box is "SimpleFacets" ... it's designed to meet simple faceting needs ... when you start talking about 100s or thousands of constraints per facet, you are getting outside the scope of what it was intended to serve efficiently. At a certain point the only practical thing to do is write a custom request handler that makes the best choices for your data. For the record: a really simple patch someone could submit would be to make add an optional field based param indicating which type of faceting (termenum/fieldcache) should be used to generate the list of terms and then make SimpleFacets.getFacetFieldCounts use that and call the apprpriate method insteado calling getTermCounts -- that way you could force one or the other if you know it's better for your data/query. -Hoss
