Field Detail

• orderedGroups

  protected TreeSet<CollectedSearchGroup<T>> orderedGroups

Constructor Detail

• FirstPassGroupingCollector

  public FirstPassGroupingCollector(Sort groupSort,
                                    int topNGroups)
                             throws IOException

  Create the first pass collector.

  Parameters:

  groupSort - The Sort used to sort the groups. The top sorted document within each group according to groupSort, determines how that group sorts against other groups. This must be non-null, ie, if you want to groupSort by relevance use Sort.RELEVANCE.

  topNGroups - How many top groups to keep.

  Throws:

  IOException - If I/O related errors occur

Method Detail

• needsScores

  public boolean needsScores()

  Description copied from interface: Collector
  Indicates if document scores are needed by this collector.

  Returns:

  true if scores are needed.

• getTopGroups

  public Collection<SearchGroup<T>> getTopGroups(int groupOffset,
                                                 boolean fillFields)

  Returns top groups, starting from offset. This may return null, if no groups were collected, or if the number of unique groups collected is <= offset.

  Parameters:

  groupOffset - The offset in the collected groups

  fillFields - Whether to fill to SearchGroup.sortValues

  Returns:

  top groups, starting from offset

• setScorer

  public void setScorer(Scorer scorer)
                 throws IOException

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

  Specified by:

  setScorer in interface LeafCollector

  Overrides:

  setScorer in class SimpleCollector

  Throws:

  IOException

• collect

  public void collect(int doc)
               throws IOException

  Description copied from interface: LeafCollector
  Called once for every document matching a query, with the unbased document number.

  Note: The collection of the current segment can be terminated by throwing a CollectionTerminatedException. In this case, the last docs of the current LeafReaderContext will be skipped and IndexSearcher will swallow the exception and continue collection with the next leaf.

  Note: This is called in an inner search loop. For good search performance, implementations of this method should not call IndexSearcher.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 interface LeafCollector

  Specified by:

  collect in class SimpleCollector

  Throws:

  IOException

• doSetNextReader

  protected void doSetNextReader(LeafReaderContext readerContext)
                          throws IOException

  Description copied from class: SimpleCollector
  This method is called before collecting context.

  Overrides:

  doSetNextReader in class SimpleCollector

  Throws:

  IOException

• getDocGroupValue

  protected abstract T getDocGroupValue(int doc)
                                 throws IOException

  Returns the group value for the specified doc.

  Parameters:

  doc - The specified doc

  Returns:

  the group value for the specified doc

  Throws:

  IOException

• copyDocGroupValue

  protected abstract T copyDocGroupValue(T groupValue,
                                         T reuse)

  Returns a copy of the specified group value by creating a new instance and copying the value from the specified groupValue in the new instance. Or optionally the reuse argument can be used to copy the group value in.

  Parameters:

  groupValue - The group value to copy

  reuse - Optionally a reuse instance to prevent a new instance creation

  Returns:

  a copy of the specified group value