Class Summary
Class	Description
DrillDownQuery	A `Query` for drill-down over facet categories.
DrillSideways	Computes drill down and sideways counts for the provided `DrillDownQuery`.
DrillSideways.DrillSidewaysResult	Result of a drill sideways search, including the `Facets` and `TopDocs`.
FacetField	Add an instance of this to your `Document` for every facet label.
FacetResult	Counts or aggregates for a single dimension.
Facets	Common base class for all facets implementations.
FacetsCollector	Collects hits for subsequent faceting.
FacetsCollector.Docs	Used during collection to record matching docs and then return a `DocIdSet` that contains them.
FacetsCollector.MatchingDocs	Holds the documents that were matched in the `AtomicReaderContext`.
FacetsConfig	Records per-dimension configuration.
FacetsConfig.DimConfig	Holds the configuration for one dimension
LabelAndValue	Single label and its value, usually contained in a `FacetResult`.
MultiFacets	Maps specified dims to provided Facets impls; else, uses the default Facets impl.
TopOrdAndFloatQueue	Keeps highest results, first by largest float value, then tie break by smallest ord.
TopOrdAndFloatQueue.OrdAndValue	Holds a single entry.
TopOrdAndIntQueue	Keeps highest results, first by largest int value, then tie break by smallest ord.
TopOrdAndIntQueue.OrdAndValue	Holds a single entry.

Package org.apache.lucene.facet Description

faceted search

This module provides multiple methods for computing facet counts and value aggregations:

Taxonomy-based methods rely on a separate taxonomy index to map hierarchical facet paths to global int ordinals for fast counting at search time; these methods can compute counts ((FastTaxonomyFacetCounts, TaxonomyFacetCounts) aggregate long or double values TaxonomyFacetSumIntAssociations, TaxonomyFacetSumFloatAssociations, TaxonomyFacetSumValueSource. Add FacetField or AssociationFacetField to your documents at index time to use taxonomy-based methods.
Sorted-set doc values method does not require a separate taxonomy index, and computes counts based on sorted set doc values fields (SortedSetDocValuesFacetCounts). Add SortedSetDocValuesFacetField to your documents at index time to use sorted set facet counts.
Range faceting LongRangeFacetCounts, DoubleRangeFacetCounts compute counts for a dynamic numeric range from a provided ValueSource (previously indexed numeric field, or a dynamic expression such as distance).

At search time you first run your search, but pass a FacetsCollector to gather all hits (and optionally, scores for each hit). Then, instantiate whichever facet methods you'd like to use to compute aggregates. Finally, all methods implement a common Facets base API that you use to obtain specific facet counts.

The various FacetsCollector.search(org.apache.lucene.search.IndexSearcher, org.apache.lucene.search.Query, int, org.apache.lucene.search.Collector) utility methods are useful for doing an "ordinary" search (sorting by score, or by a specified Sort) but also collecting into a FacetsCollector for subsequent faceting.