Package org.apache.lucene.search.grouping

Class TermGroupFacetCollectorManager

java.lang.Object

org.apache.lucene.search.grouping.TermGroupFacetCollectorManager

All Implemented Interfaces:

CollectorManager<org.apache.lucene.search.grouping.TermGroupFacetCollectorManager.FacetCollector,GroupedFacetResult>

public class TermGroupFacetCollectorManager
extends Object
implements CollectorManager<org.apache.lucene.search.grouping.TermGroupFacetCollectorManager.FacetCollector,GroupedFacetResult>

A CollectorManager for computing grouped facet counts based on term DocValues.

For each facet value, the result counts the number of distinct group values that have at least one document with that facet value. Groups spanning multiple search slices are counted exactly once (cross-slice deduplication is handled in reduce(java.util.Collection<org.apache.lucene.search.grouping.TermGroupFacetCollectorManager.FacetCollector>)).

When minCount is 0, zero-count facet terms are included in the result. Those terms must be copied to BytesRef at LeafCollector.finish() time because reduce(java.util.Collection<org.apache.lucene.search.grouping.TermGroupFacetCollectorManager.FacetCollector>) no longer has access to per-segment DocValues. On a high-cardinality facet field this can use substantially more memory than when minCount > 0, which only materializes terms that were actually collected.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary

Constructors

Constructor	Description
TermGroupFacetCollectorManager(String groupField, String facetField, boolean facetFieldMultivalued, BytesRef facetPrefix, int size, int minCount, boolean orderByCount)	Creates a new TermGroupFacetCollectorManager.

Method Summary

Modifier and Type	Method	Description
org.apache.lucene.search.grouping.TermGroupFacetCollectorManager.FacetCollector	newCollector()
GroupedFacetResult	reduce(Collection<org.apache.lucene.search.grouping.TermGroupFacetCollectorManager.FacetCollector> collectors)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

TermGroupFacetCollectorManager

public TermGroupFacetCollectorManager(String groupField,
 String facetField,
 boolean facetFieldMultivalued,
 BytesRef facetPrefix,
 int size,
 int minCount,
 boolean orderByCount)

Creates a new TermGroupFacetCollectorManager.

Parameters:

groupField - the group field

facetField - the facet field

facetFieldMultivalued - whether the facet field has multiple values per document

facetPrefix - only include facet entries with this prefix; may be null

size - the maximum number of facet entries to include in the result (offset + limit)

minCount - minimum count for a facet entry to be included. 0 includes zero-count terms and materializes every in-range facet term (see class javadoc)

orderByCount - whether to sort facet entries by count descending (vs. lexicographic)

Method Details

newCollector

public org.apache.lucene.search.grouping.TermGroupFacetCollectorManager.FacetCollector newCollector()

Specified by:

newCollector in interface CollectorManager<org.apache.lucene.search.grouping.TermGroupFacetCollectorManager.FacetCollector,GroupedFacetResult>

reduce

public GroupedFacetResult reduce(Collection<org.apache.lucene.search.grouping.TermGroupFacetCollectorManager.FacetCollector> collectors)
                          throws IOException

Specified by:

reduce in interface CollectorManager<org.apache.lucene.search.grouping.TermGroupFacetCollectorManager.FacetCollector,GroupedFacetResult>

Throws:

IOException