org.apache.lucene.search

Class EarlyTerminatingSortingCollector

java.lang.Object

org.apache.lucene.search.FilterCollector

org.apache.lucene.search.EarlyTerminatingSortingCollector

All Implemented Interfaces:

Collector

public class EarlyTerminatingSortingCollector
extends FilterCollector

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 segments sorted according to a an IndexWriterConfig.setIndexSort(org.apache.lucene.search.Sort). 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 vastly underestimated since not all matching documents will have been collected.

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 int	numDocsToCollect Number of documents to collect in each segment
protected Sort	sort Sort used to sort the search results

Fields inherited from class org.apache.lucene.search.FilterCollector

in

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
static boolean	canEarlyTerminate(Sort searchSort, Sort mergePolicySort) Returns whether collection can be early-terminated if it sorts with the provided Sort and if segments are merged with the provided Sort.
LeafCollector	getLeafCollector(LeafReaderContext context) Create a new collector to collect the given context.
boolean	terminatedEarly()

Methods inherited from class org.apache.lucene.search.FilterCollector

needsScores, toString

Methods inherited from class java.lang.Object

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

Field Detail

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

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.

Throws:

IllegalArgumentException - if the sort order doesn't allow for early termination with the given merge policy.

Method Detail

canEarlyTerminate

public static boolean canEarlyTerminate(Sort searchSort,
                                        Sort mergePolicySort)

Returns whether collection can be early-terminated if it sorts with the provided Sort and if segments are merged with the provided Sort.

getLeafCollector

public LeafCollector getLeafCollector(LeafReaderContext context)
                               throws IOException

Description copied from interface: Collector

Create a new collector to collect the given context.

Specified by:

getLeafCollector in interface Collector

Overrides:

getLeafCollector in class FilterCollector

Parameters:

context - next atomic reader context

Throws:

IOException

terminatedEarly

public boolean terminatedEarly()