org.apache.lucene.index.sorter

Class EarlyTerminatingSortingCollector

java.lang.Object

org.apache.lucene.search.Collector

org.apache.lucene.index.sorter.EarlyTerminatingSortingCollector

public class EarlyTerminatingSortingCollector
extends Collector

A Collector that early terminates collection of documents on a per-segment basis, if the segment was sorted according to the given Sort.

NOTE: the Collector detects sorted segments according to SortingMergePolicy, so it's best used in conjunction with it. Also, it collects up to a specified numDocsToCollect from each segment, and therefore is mostly suitable for use in conjunction with collectors such as TopDocsCollector, and not e.g. TotalHitCountCollector.

NOTE: If you wrap a TopDocsCollector that sorts in the same order as the index order, the returned TopDocs will be correct. However the total of hit count will be underestimated since not all matching documents will have been collected.

NOTE: This Collector uses Sort.toString() to detect whether a segment was sorted with the same Sort. This has two implications:

• if a custom comparator is not implemented correctly and returns different identifiers for equivalent instances, this collector will not detect sorted segments,
• if you suddenly change the IndexWriter's SortingMergePolicy to sort according to another criterion and if both the old and the new Sorts have the same identifier, this Collector will incorrectly detect sorted segments.

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

Field Summary

Fields

Modifier and Type	Field and Description
protected Collector	in The wrapped Collector
protected int	numDocsToCollect Number of documents to collect in each segment
protected boolean	segmentSorted True if the current segment being processed is sorted by sort
protected int	segmentTotalCollect Number of documents to collect in the current segment being processed
protected Sort	sort Sort used to sort the search results

Constructor Summary

Constructors

Constructor and Description
EarlyTerminatingSortingCollector(Collector in, Sort sort, int numDocsToCollect) Create a new EarlyTerminatingSortingCollector instance.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	acceptsDocsOutOfOrder()
void	collect(int doc)
void	setNextReader(AtomicReaderContext context)
void	setScorer(Scorer scorer)

Methods inherited from class java.lang.Object

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

Field Detail

in

protected final Collector in

The wrapped Collector

sort

protected final Sort sort

Sort used to sort the search results

numDocsToCollect

protected final int numDocsToCollect

Number of documents to collect in each segment

segmentTotalCollect

protected int segmentTotalCollect

Number of documents to collect in the current segment being processed

segmentSorted

protected boolean segmentSorted

True if the current segment being processed is sorted by sort

Constructor Detail

EarlyTerminatingSortingCollector

public EarlyTerminatingSortingCollector(Collector in,
                                Sort sort,
                                int numDocsToCollect)

Create a new EarlyTerminatingSortingCollector instance.

Parameters:

in - the collector to wrap

sort - the sort you are sorting the search results on

numDocsToCollect - the number of documents to collect on each segment. When wrapping a TopDocsCollector, this number should be the number of hits.

Method Detail

setScorer

public void setScorer(Scorer scorer)
               throws IOException

Specified by:

setScorer in class Collector

Throws:

IOException

collect

public void collect(int doc)
             throws IOException

Specified by:

collect in class Collector

Throws:

IOException

setNextReader

public void setNextReader(AtomicReaderContext context)
                   throws IOException

Specified by:

setNextReader in class Collector

Throws:

IOException

acceptsDocsOutOfOrder

public boolean acceptsDocsOutOfOrder()

Specified by:

acceptsDocsOutOfOrder in class Collector