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. This collector optionally supports searching after a previous result through the 'after' parameter. 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 String
    collapseField
     
    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​(String collapseField, MappedFieldType collapseFieldType, org.apache.lucene.search.Sort sort, int topN, org.apache.lucene.search.FieldDoc after)
    Create a collapsing top docs collector on a SortedDocValues field.
    static CollapsingTopDocsCollector<?>
    createNumeric​(String collapseField, MappedFieldType collapseFieldType, org.apache.lucene.search.Sort sort, int topN, org.apache.lucene.search.FieldDoc after)
    Create a collapsing top docs collector on a NumericDocValues field.
    protected void
    doSetNextReader​(org.apache.lucene.index.LeafReaderContext readerContext)
     
    CollapseTopFieldDocs
    getTopDocs()
    Transform FirstPassGroupingCollector.getTopGroups(int) output in CollapseTopFieldDocs.
    org.apache.lucene.search.ScoreMode
    scoreMode()
     

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

    getGroupSelector, getTopGroups, setScorer

    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 String collapseField

    • sort

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

  • Method Details

    • getTopDocs

      public CollapseTopFieldDocs getTopDocs() throws 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:
      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>

    • doSetNextReader

      protected void doSetNextReader​(org.apache.lucene.index.LeafReaderContext readerContext) throws IOException
      Overrides:
      doSetNextReader in class org.apache.lucene.search.grouping.FirstPassGroupingCollector<T>
      Throws:
      IOException

    • collect

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

    • createNumeric

      public static CollapsingTopDocsCollector<?> createNumeric​(String collapseField, MappedFieldType collapseFieldType, org.apache.lucene.search.Sort sort, int topN, @Nullable org.apache.lucene.search.FieldDoc after)
      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.
      after - The field values to search after. Can be null.

    • createKeyword

      public static CollapsingTopDocsCollector<?> createKeyword​(String collapseField, MappedFieldType collapseFieldType, org.apache.lucene.search.Sort sort, int topN, @Nullable org.apache.lucene.search.FieldDoc after)
      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.
      after - The field values to search after. Can be null.