org.apache.lucene.search.grouping

Class AbstractAllGroupHeadsCollector<GH extends AbstractAllGroupHeadsCollector.GroupHead>

java.lang.Object

org.apache.lucene.search.Collector

org.apache.lucene.search.grouping.AbstractAllGroupHeadsCollector<GH>

Direct Known Subclasses:

TermAllGroupHeadsCollector

public abstract class AbstractAllGroupHeadsCollector<GH extends AbstractAllGroupHeadsCollector.GroupHead>
extends Collector

This collector specializes in collecting the most relevant document (group head) for each group that match the query.

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

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AbstractAllGroupHeadsCollector.GroupHead<GROUP_VALUE_TYPE> Represents a group head.
protected class	AbstractAllGroupHeadsCollector.TemporalResult Contains the result of group head retrieval.

Field Summary

Fields

Modifier and Type	Field and Description
protected int	compIDXEnd
protected int[]	reversed
protected AbstractAllGroupHeadsCollector.TemporalResult	temporalResult

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractAllGroupHeadsCollector(int numberOfSorts)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	acceptsDocsOutOfOrder() Return true if this collector does not require the matching docIDs to be delivered in int sort order (smallest to largest) to Collector.collect(int).
void	collect(int doc) Called once for every document matching a query, with the unbased document number.
protected abstract Collection<GH>	getCollectedGroupHeads() Returns the collected group heads.
int	groupHeadsSize()
protected abstract void	retrieveGroupHeadAndAddIfNotExist(int doc) Returns the group head and puts it into temporalResult.
int[]	retrieveGroupHeads()
FixedBitSet	retrieveGroupHeads(int maxDoc)

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

setNextReader, setScorer

Methods inherited from class java.lang.Object

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

Field Detail

reversed

protected final int[] reversed

compIDXEnd

protected final int compIDXEnd

temporalResult

protected final AbstractAllGroupHeadsCollector.TemporalResult temporalResult

Constructor Detail

AbstractAllGroupHeadsCollector

protected AbstractAllGroupHeadsCollector(int numberOfSorts)

Method Detail

retrieveGroupHeads

public FixedBitSet retrieveGroupHeads(int maxDoc)

Parameters:

maxDoc - The maxDoc of the top level IndexReader.

Returns:

an FixedBitSet containing all group heads.

retrieveGroupHeads

public int[] retrieveGroupHeads()

Returns:

an int array containing all group heads. The size of the array is equal to number of collected unique groups.

groupHeadsSize

public int groupHeadsSize()

Returns:

the number of group heads found for a query.

retrieveGroupHeadAndAddIfNotExist

protected abstract void retrieveGroupHeadAndAddIfNotExist(int doc)
                                                   throws IOException

Returns the group head and puts it into temporalResult. If the group head wasn't encountered before then it will be added to the collected group heads.

The AbstractAllGroupHeadsCollector.TemporalResult.stop property will be true if the group head wasn't encountered before otherwise false.

Parameters:

doc - The document to retrieve the group head for.

Throws:

IOException - If I/O related errors occur

getCollectedGroupHeads

protected abstract Collection<GH> getCollectedGroupHeads()

Returns the collected group heads. Subsequent calls should return the same group heads.

Returns:

the collected group heads

collect

public void collect(int doc)
             throws IOException

Description copied from class: Collector

Called once for every document matching a query, with the unbased document number.

Note: This is called in an inner search loop. For good search performance, implementations of this method should not call Searcher.doc(int) or IndexReader.document(int) on every hit. Doing so can slow searches by an order of magnitude or more.

Specified by:

collect in class Collector

Throws:

IOException

acceptsDocsOutOfOrder

public boolean acceptsDocsOutOfOrder()

Description copied from class: Collector

Return true if this collector does not require the matching docIDs to be delivered in int sort order (smallest to largest) to Collector.collect(int).

Most Lucene Query implementations will visit matching docIDs in order. However, some queries (currently limited to certain cases of BooleanQuery) can achieve faster searching if the Collector allows them to deliver the docIDs out of order.

Many collectors don't mind getting docIDs out of order, so it's important to return true here.

Specified by:

acceptsDocsOutOfOrder in class Collector