A field facet query computes the top values for a field and returns the list of those values along with a count of the subset
of documents in the search results which match that term.
Field faceting works best over fields which contain a single label or set of labels from a finite, controlled lexicon
such as product category.
Facet field parameters can be tuned for performance, see:
Facet Field Configuration.
It’s possible to specify more than one field facets.
For each field facet you must specify the field name plus the following additional parameters:
Limit – the maximum number of terms to be returned. Default 100.
Offset – the number of top facet values to skip in the response. Default 0.
Sort - the order in which to list facet values: count ordering is by documents per term, descending, and index ordering is sorted on term values themselves.
Missing - the number of documents in the results set which have no value for the facet field.
Choice of facet method (advanced) - specify Solr algorithm used to calculate facet counts.
(See Facet Method Configuration for details).
enum - small number of distinct categories
fc ("field cache") - many different values in the field, each document has low number of values, multi-valued field
fcs ("single value string fields") - good for rapidly changing indexes