Package org.apache.lucene.search.grouping

Class AllGroupHeadsCollectorManager<T>

java.lang.Object

org.apache.lucene.search.grouping.AllGroupHeadsCollectorManager<T>

Type Parameters:

T - the type of the group value

All Implemented Interfaces:

CollectorManager<AllGroupHeadsCollector<T>,AllGroupHeadsCollectorManager.GroupHeadsResult>

public class AllGroupHeadsCollectorManager<T>
extends Object
implements CollectorManager<AllGroupHeadsCollector<T>,AllGroupHeadsCollectorManager.GroupHeadsResult>

A CollectorManager implementation for AllGroupHeadsCollector that collects the most relevant document (group head) for each group across multiple segments and merges the per-segment results into a single AllGroupHeadsCollectorManager.GroupHeadsResult.

Example usage:

 IndexSearcher searcher = ...; // your IndexSearcher
 AllGroupHeadsCollectorManager<BytesRef> manager =
     new AllGroupHeadsCollectorManager<>(
         () -> new TermGroupSelector("category"), Sort.RELEVANCE);
 GroupHeadsResult result = searcher.search(new MatchAllDocsQuery(), manager);
 Bits groupHeadsBits = result.retrieveGroupHeads(searcher.getIndexReader().maxDoc());
 

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

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	AllGroupHeadsCollectorManager.GroupHeadsResult	Holds the merged group heads and provides access as an int[] or Bits.

Constructor Summary

Constructors

Constructor	Description
AllGroupHeadsCollectorManager(Supplier<GroupSelector<T>> groupSelectorFactory, Sort sortWithinGroup)	Creates a new AllGroupHeadsCollectorManager.

Method Summary

Modifier and Type	Method	Description
AllGroupHeadsCollector<T>	newCollector()
AllGroupHeadsCollectorManager.GroupHeadsResult	reduce(Collection<AllGroupHeadsCollector<T>> collectors)

Methods inherited from class java.lang.Object

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

Constructor Details

AllGroupHeadsCollectorManager

public AllGroupHeadsCollectorManager(Supplier<GroupSelector<T>> groupSelectorFactory,
 Sort sortWithinGroup)

Creates a new AllGroupHeadsCollectorManager.

Parameters:

groupSelectorFactory - factory to create group selectors for each collector

sortWithinGroup - the sort to use within each group to determine the group head

Method Details

newCollector

public AllGroupHeadsCollector<T> newCollector()
                                       throws IOException

Specified by:

newCollector in interface CollectorManager<AllGroupHeadsCollector<T>,AllGroupHeadsCollectorManager.GroupHeadsResult>

Throws:

IOException

reduce

public AllGroupHeadsCollectorManager.GroupHeadsResult reduce(Collection<AllGroupHeadsCollector<T>> collectors)

Specified by:

reduce in interface CollectorManager<AllGroupHeadsCollector<T>,AllGroupHeadsCollectorManager.GroupHeadsResult>