org.apache.lucene.search.grouping
Class AbstractSecondPassGroupingCollector<GROUP_VALUE_TYPE>

java.lang.Object
  org.apache.lucene.search.Collector
      org.apache.lucene.search.grouping.AbstractSecondPassGroupingCollector<GROUP_VALUE_TYPE>

Direct Known Subclasses:

TermSecondPassGroupingCollector

public abstract class AbstractSecondPassGroupingCollector<GROUP_VALUE_TYPE>
extends Collector

SecondPassGroupingCollector is the second of two passes necessary to collect grouped docs. This pass gathers the top N documents per top group computed from the first pass. Concrete subclasses define what a group is and how it is internally collected.

See org.apache.lucene.search.grouping for more details including a full code example.

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

Nested Class Summary

class

AbstractSecondPassGroupingCollector.SearchGroupDocs<GROUP_VALUE_TYPE>

Field Summary

protected AbstractSecondPassGroupingCollector.SearchGroupDocs<GROUP_VALUE_TYPE>[]	groupDocs
protected Map<GROUP_VALUE_TYPE,AbstractSecondPassGroupingCollector.SearchGroupDocs<GROUP_VALUE_TYPE>>	groupMap

Constructor Summary

AbstractSecondPassGroupingCollector(Collection<SearchGroup<GROUP_VALUE_TYPE>> groups, Sort groupSort, Sort withinGroupSort, int maxDocsPerGroup, boolean getScores, boolean getMaxScores, boolean fillSortFields)

Method Summary

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.
TopGroups<GROUP_VALUE_TYPE>	getTopGroups(int withinGroupOffset)
protected abstract AbstractSecondPassGroupingCollector.SearchGroupDocs<GROUP_VALUE_TYPE>	retrieveGroup(int doc) Returns the group the specified doc belongs to or null if no group could be retrieved.
void	setNextReader(IndexReader reader, int docBase) Called before collecting from each IndexReader.
void	setScorer(Scorer scorer) Called before successive calls to Collector.collect(int).

Methods inherited from class java.lang.Object

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

Field Detail

groupMap

protected final Map<GROUP_VALUE_TYPE,AbstractSecondPassGroupingCollector.SearchGroupDocs<GROUP_VALUE_TYPE>> groupMap

groupDocs

protected AbstractSecondPassGroupingCollector.SearchGroupDocs<GROUP_VALUE_TYPE>[] groupDocs

Constructor Detail

AbstractSecondPassGroupingCollector

public AbstractSecondPassGroupingCollector(Collection<SearchGroup<GROUP_VALUE_TYPE>> groups,
                                           Sort groupSort,
                                           Sort withinGroupSort,
                                           int maxDocsPerGroup,
                                           boolean getScores,
                                           boolean getMaxScores,
                                           boolean fillSortFields)
                                    throws IOException

Throws:

IOException

Method Detail

setScorer

public void setScorer(Scorer scorer)
               throws IOException

Description copied from class: Collector

Called before successive calls to Collector.collect(int). Implementations that need the score of the current document (passed-in to Collector.collect(int)), should save the passed-in Scorer and call scorer.score() when needed.

Specified by:

setScorer in class Collector

Throws:

IOException

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

retrieveGroup

protected abstract AbstractSecondPassGroupingCollector.SearchGroupDocs<GROUP_VALUE_TYPE> retrieveGroup(int doc)
                                                                                                throws IOException

Returns the group the specified doc belongs to or null if no group could be retrieved.

Parameters:

doc - The specified doc

Returns:

the group the specified doc belongs to or null if no group could be retrieved

Throws:

IOException - If an I/O related error occurred

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

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

getTopGroups

public TopGroups<GROUP_VALUE_TYPE> getTopGroups(int withinGroupOffset)