Package org.apache.lucene.search.grouping

Class CollapsingTopDocsCollector<T>

java.lang.Object
org.apache.lucene.search.SimpleCollector
org.apache.lucene.search.grouping.FirstPassGroupingCollector<T>
org.apache.lucene.search.grouping.CollapsingTopDocsCollector<T>
All Implemented Interfaces:
org.apache.lucene.search.Collector, org.apache.lucene.search.LeafCollector
public final class CollapsingTopDocsCollector<T>
extends org.apache.lucene.search.grouping.FirstPassGroupingCollector<T>
A collector that groups documents based on field values and returns CollapseTopFieldDocs output. The collapsing is done in a single pass by selecting only the top sorted document per collapse key. The value used for the collapse key of each group can be found in CollapseTopFieldDocs.collapseValues. TODO: If the sort is based on score we should propagate the mininum competitive score when orderedGroups is full. This is safe for collapsing since the group sort is the same as the query sort.

  • Field Summary

    Fields
    Modifier and Type Field Description
    protected java.lang.String collapseField  
    protected org.apache.lucene.search.Scorable scorer  
    protected org.apache.lucene.search.Sort sort  

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

    orderedGroups

  • Method Summary

    Modifier and Type Method Description
    void collect​(int doc)  
    static CollapsingTopDocsCollector<?> createKeyword​(java.lang.String collapseField, MappedFieldType collapseFieldType, org.apache.lucene.search.Sort sort, int topN)
    Create a collapsing top docs collector on a SortedDocValues field.
    static CollapsingTopDocsCollector<?> createNumeric​(java.lang.String collapseField, MappedFieldType collapseFieldType, org.apache.lucene.search.Sort sort, int topN)
    Create a collapsing top docs collector on a NumericDocValues field.
    CollapseTopFieldDocs getTopDocs()
    Transform FirstPassGroupingCollector.getTopGroups(int) output in CollapseTopFieldDocs.
    org.apache.lucene.search.ScoreMode scoreMode()  
    void setScorer​(org.apache.lucene.search.Scorable scorer)  

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

    doSetNextReader, getGroupSelector, getTopGroups

    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

    Methods inherited from interface org.apache.lucene.search.LeafCollector

    competitiveIterator

  • Field Details

    • collapseField

      protected final java.lang.String collapseField

    • sort

      protected final org.apache.lucene.search.Sort sort

    • scorer

      protected org.apache.lucene.search.Scorable scorer

  • Method Details

    • getTopDocs

      public CollapseTopFieldDocs getTopDocs() throws java.io.IOException
      Transform FirstPassGroupingCollector.getTopGroups(int) output in CollapseTopFieldDocs. The collapsing needs only one pass so we can get the final top docs at the end of the first pass.
      Throws:
      java.io.IOException

    • scoreMode

      public org.apache.lucene.search.ScoreMode scoreMode()
      Specified by:
      scoreMode in interface org.apache.lucene.search.Collector
      Overrides:
      scoreMode in class org.apache.lucene.search.grouping.FirstPassGroupingCollector<T>

    • setScorer

      public void setScorer​(org.apache.lucene.search.Scorable scorer) throws java.io.IOException
      Specified by:
      setScorer in interface org.apache.lucene.search.LeafCollector
      Overrides:
      setScorer in class org.apache.lucene.search.grouping.FirstPassGroupingCollector<T>
      Throws:
      java.io.IOException

    • collect

      public void collect​(int doc) throws java.io.IOException
      Specified by:
      collect in interface org.apache.lucene.search.LeafCollector
      Overrides:
      collect in class org.apache.lucene.search.grouping.FirstPassGroupingCollector<T>
      Throws:
      java.io.IOException

    • createNumeric

      public static CollapsingTopDocsCollector<?> createNumeric​(java.lang.String collapseField, MappedFieldType collapseFieldType, org.apache.lucene.search.Sort sort, int topN)
      Create a collapsing top docs collector on a NumericDocValues field. It accepts also SortedNumericDocValues field but the collect will fail with an IllegalStateException if a document contains more than one value for the field.
      Parameters:
      collapseField - The sort field used to group documents.
      collapseFieldType - The MappedFieldType for this sort field.
      sort - The Sort used to sort the collapsed hits. The collapsing keeps only the top sorted document per collapsed key. This must be non-null, ie, if you want to groupSort by relevance use Sort.RELEVANCE.
      topN - How many top groups to keep.

    • createKeyword

      public static CollapsingTopDocsCollector<?> createKeyword​(java.lang.String collapseField, MappedFieldType collapseFieldType, org.apache.lucene.search.Sort sort, int topN)
      Create a collapsing top docs collector on a SortedDocValues field. It accepts also SortedSetDocValues field but the collect will fail with an IllegalStateException if a document contains more than one value for the field.
      Parameters:
      collapseField - The sort field used to group documents.
      collapseFieldType - The MappedFieldType for this sort field.
      sort - The Sort used to sort the collapsed hits. The collapsing keeps only the top sorted document per collapsed key. This must be non-null, ie, if you want to groupSort by relevance use Sort.RELEVANCE.
      topN - How many top groups to keep.