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.

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

Field Summary

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

orderedGroups

Constructor Summary

Constructors

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

Method Summary

Methods

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)
protected BytesRef	getDocGroupValue(int doc) Returns the group value for the specified doc.
boolean	needsScores()

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

collect, getTopGroups, 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

Constructor Detail

TermFirstPassGroupingCollector

public TermFirstPassGroupingCollector(String groupField,
                              Sort groupSort,
                              int topNGroups)
                               throws 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:

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 IOException

Overrides:

doSetNextReader in class AbstractFirstPassGroupingCollector<BytesRef>

Throws:

IOException

needsScores

public boolean needsScores()