Solr's faceting is broken down into five types. They are as follows:
field: This is the most common type of faceting which counts the number of occurrences of each indexed term in a field. The facet counts are grouped in the output under the namefacet_fields.range: Given a numeric or date field, this creates facets for a set of ranges. The facet counts are grouped in the output under the namefacet_ranges.query: This is a very flexible type of faceting which counts the number of documents matching each specified query. The facet counts are grouped in the output underfacet_queries.pivot: Also known as decision tree faceting, this type of faceting allows recursive faceting across a set of fields. Results are grouped underfacet_pivot.interval: A Solr 4.10-only feature, an interval facet is similar to a query facet with range queries. While the same results...