org.apache.lucene.search.grouping

Class TermAllGroupsCollector

java.lang.Object

org.apache.lucene.search.Collector

org.apache.lucene.search.grouping.AbstractAllGroupsCollector<String>

org.apache.lucene.search.grouping.TermAllGroupsCollector

public class TermAllGroupsCollector
extends AbstractAllGroupsCollector<String>

A collector that collects all groups that match the query. Only the group value is collected, and the order is undefined. This collector does not determine the most relevant document of a group.

Implementation detail: an int hash set (SentinelIntSet) is used to detect if a group is already added to the total count. For each segment the int set is cleared and filled with previous counted groups that occur in the new segment.

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

Constructor Summary

Constructors

Constructor and Description
TermAllGroupsCollector(String groupField) Constructs a AbstractAllGroupsCollector.
TermAllGroupsCollector(String groupField, int initialSize) Expert: Constructs a AbstractAllGroupsCollector

Method Summary

Methods

Modifier and Type	Method and Description
void	collect(int doc) Called once for every document matching a query, with the unbased document number.
Collection<String>	getGroups() Returns the group values This is an unordered collections of group values.
void	setNextReader(IndexReader reader, int docBase) Called before collecting from each IndexReader.

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

acceptsDocsOutOfOrder, getGroupCount, setScorer

Methods inherited from class java.lang.Object

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

Constructor Detail

TermAllGroupsCollector

public TermAllGroupsCollector(String groupField,
                      int initialSize)

Expert: Constructs a AbstractAllGroupsCollector

Parameters:

groupField - The field to group by

initialSize - The initial allocation size of the internal int set and group list which should roughly match the total number of expected unique groups. Be aware that the heap usage is 4 bytes * initialSize.

TermAllGroupsCollector

public TermAllGroupsCollector(String groupField)

Constructs a AbstractAllGroupsCollector. This sets the initial allocation size for the internal int set and group list to 128.

Parameters:

groupField - The field to group by

Method Detail

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

getGroups

public Collection<String> getGroups()

Returns the group values

This is an unordered collections of group values. For each group that matched the query there is a BytesRef representing a group value.

Specified by:

getGroups in class AbstractAllGroupsCollector<String>

Returns:

the group values

setNextReader

public void setNextReader(IndexReader reader,
                 int docBase)
                   throws IOException

Description copied from class: Collector

Called before collecting from each IndexReader. All doc ids in Collector.collect(int) will correspond to reader. Add docBase to the current IndexReaders internal document id to re-base ids in Collector.collect(int).

Specified by:

setNextReader in class Collector

Parameters:

reader - next IndexReader

Throws:

IOException