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

java.lang.Object
  extended by org.apache.lucene.search.Collector
      extended by 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)


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