org.apache.lucene.search.grouping.term

Class TermFirstPassGroupingCollector

java.lang.Object

org.apache.lucene.search.SimpleCollector

org.apache.lucene.search.grouping.AbstractFirstPassGroupingCollector<BytesRef>

org.apache.lucene.search.grouping.term.TermFirstPassGroupingCollector

All Implemented Interfaces:

Collector, LeafCollector

public class TermFirstPassGroupingCollector
extends AbstractFirstPassGroupingCollector<BytesRef>

Concrete implementation of AbstractFirstPassGroupingCollector that groups based on field values and more specifically uses SortedDocValues to collect groups.

Field Summary

Fields

Modifier and Type	Field and Description
private java.lang.String	groupField
private SortedDocValues	index

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

orderedGroups

Constructor Summary

Constructors

Constructor and Description
TermFirstPassGroupingCollector(java.lang.String groupField, Sort groupSort, int topNGroups) Create the first pass collector.

Method Summary

Modifier and Type	Method and Description
protected BytesRef	copyDocGroupValue(BytesRef groupValue, BytesRef reuse) Returns a copy of the specified group value by creating a new instance and copying the value from the specified groupValue in the new instance.
protected void	doSetNextReader(LeafReaderContext readerContext) This method is called before collecting context.
protected BytesRef	getDocGroupValue(int doc) Returns the group value for the specified doc.

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

collect, getTopGroups, needsScores, setScorer

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

getLeafCollector

Methods inherited from class java.lang.Object

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

Field Detail

index

private SortedDocValues index

groupField

private java.lang.String groupField

Constructor Detail

TermFirstPassGroupingCollector

public TermFirstPassGroupingCollector(java.lang.String groupField,
                                      Sort groupSort,
                                      int topNGroups)
                               throws java.io.IOException

Create the first pass collector.

Parameters:

groupField - The field used to group documents. This field must be single-valued and indexed (DocValues is used to access its value per-document).

groupSort - The Sort used to sort the groups. The top sorted document within each group according to groupSort, determines how that group sorts against other groups. This must be non-null, ie, if you want to groupSort by relevance use Sort.RELEVANCE.

topNGroups - How many top groups to keep.

Throws:

java.io.IOException - When I/O related errors occur

Method Detail

getDocGroupValue

protected BytesRef getDocGroupValue(int doc)

Description copied from class: AbstractFirstPassGroupingCollector

Returns the group value for the specified doc.

Specified by:

getDocGroupValue in class AbstractFirstPassGroupingCollector<BytesRef>

Parameters:

doc - The specified doc

Returns:

the group value for the specified doc

copyDocGroupValue

protected BytesRef copyDocGroupValue(BytesRef groupValue,
                                     BytesRef reuse)

Description copied from class: AbstractFirstPassGroupingCollector

Returns a copy of the specified group value by creating a new instance and copying the value from the specified groupValue in the new instance. Or optionally the reuse argument can be used to copy the group value in.

Specified by:

copyDocGroupValue in class AbstractFirstPassGroupingCollector<BytesRef>

Parameters:

groupValue - The group value to copy

reuse - Optionally a reuse instance to prevent a new instance creation

Returns:

a copy of the specified group value

doSetNextReader

protected void doSetNextReader(LeafReaderContext readerContext)
                        throws java.io.IOException

Description copied from class: SimpleCollector

This method is called before collecting context.

Overrides:

doSetNextReader in class AbstractFirstPassGroupingCollector<BytesRef>

Throws:

java.io.IOException