Package org.apache.lucene.search.grouping

Class CollapsingTopDocsCollector<T>

java.lang.Object

org.apache.lucene.search.SimpleCollector

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

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

All Implemented Interfaces:

org.apache.lucene.search.Collector, org.apache.lucene.search.LeafCollector

public final class CollapsingTopDocsCollector<T>
extends org.apache.lucene.search.grouping.FirstPassGroupingCollector<T>

A collector that groups documents based on field values and returns CollapseTopFieldDocs output. The collapsing is done in a single pass by selecting only the top sorted document per collapse key. The value used for the collapse key of each group can be found in CollapseTopFieldDocs.collapseValues.

Field Summary

Fields

Modifier and Type	Field	Description
protected java.lang.String	collapseField
protected org.apache.lucene.search.Scorer	scorer
protected org.apache.lucene.search.Sort	sort

Fields inherited from class org.apache.lucene.search.grouping.FirstPassGroupingCollector

orderedGroups

Method Summary

Modifier and Type	Method	Description
void	collect(int doc)
static CollapsingTopDocsCollector<?>	createKeyword(java.lang.String collapseField, org.apache.lucene.search.Sort sort, int topN, boolean trackMaxScore)	Create a collapsing top docs collector on a SortedDocValues field.
static CollapsingTopDocsCollector<?>	createNumeric(java.lang.String collapseField, org.apache.lucene.search.Sort sort, int topN, boolean trackMaxScore)	Create a collapsing top docs collector on a NumericDocValues field.
CollapseTopFieldDocs	getTopDocs()	Transform FirstPassGroupingCollector.getTopGroups(int, boolean) output in CollapseTopFieldDocs.
boolean	needsScores()
void	setScorer(org.apache.lucene.search.Scorer scorer)

Methods inherited from class org.apache.lucene.search.grouping.FirstPassGroupingCollector

doSetNextReader, getGroupSelector, getTopGroups

Methods inherited from class java.lang.Object

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

Methods inherited from class org.apache.lucene.search.SimpleCollector

getLeafCollector

Field Detail

collapseField

protected final java.lang.String collapseField

sort

protected final org.apache.lucene.search.Sort sort

scorer

protected org.apache.lucene.search.Scorer scorer

Method Detail

getTopDocs

public CollapseTopFieldDocs getTopDocs()
                                throws java.io.IOException

Transform FirstPassGroupingCollector.getTopGroups(int, boolean) output in CollapseTopFieldDocs. The collapsing needs only one pass so we can get the final top docs at the end of the first pass.

Throws:

java.io.IOException

needsScores

public boolean needsScores()

Specified by:

needsScores in interface org.apache.lucene.search.Collector

Overrides:

needsScores in class org.apache.lucene.search.grouping.FirstPassGroupingCollector<T>

setScorer

public void setScorer(org.apache.lucene.search.Scorer scorer)
               throws java.io.IOException

Specified by:

setScorer in interface org.apache.lucene.search.LeafCollector

Overrides:

setScorer in class org.apache.lucene.search.grouping.FirstPassGroupingCollector<T>

Throws:

java.io.IOException

collect

public void collect(int doc)
             throws java.io.IOException

Specified by:

collect in interface org.apache.lucene.search.LeafCollector

Overrides:

collect in class org.apache.lucene.search.grouping.FirstPassGroupingCollector<T>

Throws:

java.io.IOException

createNumeric

public static CollapsingTopDocsCollector<?> createNumeric(java.lang.String collapseField,
                                                          org.apache.lucene.search.Sort sort,
                                                          int topN,
                                                          boolean trackMaxScore)

Create a collapsing top docs collector on a NumericDocValues field. It accepts also SortedNumericDocValues field but the collect will fail with an IllegalStateException if a document contains more than one value for the field.

Parameters:

collapseField - The sort field used to group documents.

sort - The Sort used to sort the collapsed hits. The collapsing keeps only the top sorted document per collapsed key. This must be non-null, ie, if you want to groupSort by relevance use Sort.RELEVANCE.

topN - How many top groups to keep.

createKeyword

public static CollapsingTopDocsCollector<?> createKeyword(java.lang.String collapseField,
                                                          org.apache.lucene.search.Sort sort,
                                                          int topN,
                                                          boolean trackMaxScore)

Create a collapsing top docs collector on a SortedDocValues field. It accepts also SortedSetDocValues field but the collect will fail with an IllegalStateException if a document contains more than one value for the field.

Parameters:

collapseField - The sort field used to group documents.

sort - The Sort used to sort the collapsed hits. The collapsing keeps only the top sorted document per collapsed key. This must be non-null, ie, if you want to groupSort by relevance use Sort.RELEVANCE.

topN - How many top groups to keep.