org.apache.lucene.search

Class TopFieldCollector

java.lang.Object

org.apache.lucene.search.TopDocsCollector<FieldValueHitQueue.Entry>

org.apache.lucene.search.TopFieldCollector

All Implemented Interfaces:

Collector

public abstract class TopFieldCollector
extends TopDocsCollector<FieldValueHitQueue.Entry>

A Collector that sorts by SortField using FieldComparators.

See the create(org.apache.lucene.search.Sort, int, int) method for instantiating a TopFieldCollector.

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

Field Summary

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

EMPTY_TOPDOCS, pq, totalHits, totalHitsRelation

Method Summary

Modifier and Type	Method and Description
static TopFieldCollector	create(Sort sort, int numHits, FieldDoc after, int totalHitsThreshold) Creates a new TopFieldCollector from the given arguments.
static TopFieldCollector	create(Sort sort, int numHits, int totalHitsThreshold) Creates a new TopFieldCollector from the given arguments.
static CollectorManager<TopFieldCollector,TopFieldDocs>	createSharedManager(Sort sort, int numHits, FieldDoc after, int totalHitsThreshold) Create a CollectorManager which uses a shared hit counter to maintain number of hits and a shared MaxScoreAccumulator to propagate the minimum score accross segments if the primary sort is by relevancy.
boolean	isEarlyTerminated() Return whether collection terminated early.
protected TopDocs	newTopDocs(ScoreDoc[] results, int start) Returns a TopDocs instance containing the given results.
protected void	populateResults(ScoreDoc[] results, int howMany) Populates the results array with the ScoreDoc instances.
static void	populateScores(ScoreDoc[] topDocs, IndexSearcher searcher, Query query) Populate scores of the given topDocs.
ScoreMode	scoreMode() Indicates what features are required from the scorer.
TopFieldDocs	topDocs() Returns the top docs that were collected by this collector.
protected void	updateGlobalMinCompetitiveScore(Scorable scorer)
protected void	updateMinCompetitiveScore(Scorable scorer)

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

getTotalHits, topDocs, topDocs, topDocsSize

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.Collector

getLeafCollector

Method Detail

scoreMode

public ScoreMode scoreMode()

Description copied from interface: Collector

Indicates what features are required from the scorer.

updateGlobalMinCompetitiveScore

protected void updateGlobalMinCompetitiveScore(Scorable scorer)
                                        throws IOException

Throws:

IOException

updateMinCompetitiveScore

protected void updateMinCompetitiveScore(Scorable scorer)
                                  throws IOException

Throws:

IOException

create

public static TopFieldCollector create(Sort sort,
                                       int numHits,
                                       int totalHitsThreshold)

Creates a new TopFieldCollector from the given arguments.

NOTE: The instances returned by this method pre-allocate a full array of length numHits.

Parameters:

sort - the sort criteria (SortFields).

numHits - the number of results to collect.

totalHitsThreshold - the number of docs to count accurately. If the query matches more than totalHitsThreshold hits then its hit count will be a lower bound. On the other hand if the query matches less than or exactly totalHitsThreshold hits then the hit count of the result will be accurate. Integer.MAX_VALUE may be used to make the hit count accurate, but this will also make query processing slower.

Returns:

a TopFieldCollector instance which will sort the results by the sort criteria.

create

public static TopFieldCollector create(Sort sort,
                                       int numHits,
                                       FieldDoc after,
                                       int totalHitsThreshold)

Creates a new TopFieldCollector from the given arguments.

NOTE: The instances returned by this method pre-allocate a full array of length numHits.

Parameters:

sort - the sort criteria (SortFields).

numHits - the number of results to collect.

after - only hits after this FieldDoc will be collected

totalHitsThreshold - the number of docs to count accurately. If the query matches more than totalHitsThreshold hits then its hit count will be a lower bound. On the other hand if the query matches less than or exactly totalHitsThreshold hits then the hit count of the result will be accurate. Integer.MAX_VALUE may be used to make the hit count accurate, but this will also make query processing slower. Setting totalHitsThreshold less than Integer.MAX_VALUE instructs Lucene to skip non-competitive documents whenever possible. For numeric sort fields the skipping functionality works when the same field is indexed both with doc values and points. In this case, there is an assumption that the same data is stored in these points and doc values.

Returns:

a TopFieldCollector instance which will sort the results by the sort criteria.

createSharedManager

public static CollectorManager<TopFieldCollector,TopFieldDocs> createSharedManager(Sort sort,
                                                                                   int numHits,
                                                                                   FieldDoc after,
                                                                                   int totalHitsThreshold)

Create a CollectorManager which uses a shared hit counter to maintain number of hits and a shared MaxScoreAccumulator to propagate the minimum score accross segments if the primary sort is by relevancy.

populateScores

public static void populateScores(ScoreDoc[] topDocs,
                                  IndexSearcher searcher,
                                  Query query)
                           throws IOException

Populate scores of the given topDocs.

Parameters:

topDocs - the top docs to populate

searcher - the index searcher that has been used to compute topDocs

query - the query that has been used to compute topDocs

Throws:

IllegalArgumentException - if there is evidence that topDocs have been computed against a different searcher or a different query.

IOException

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

populateResults

protected void populateResults(ScoreDoc[] results,
                               int howMany)

Description copied from class: TopDocsCollector

Populates the results array with the ScoreDoc instances. This can be overridden in case a different ScoreDoc type should be returned.

Overrides:

populateResults in class TopDocsCollector<FieldValueHitQueue.Entry>

newTopDocs

protected TopDocs newTopDocs(ScoreDoc[] results,
                             int start)

Description copied from class: TopDocsCollector

Returns a TopDocs instance containing the given results. If results is null it means there are no results to return, either because there were 0 calls to collect() or because the arguments to topDocs were invalid.

Overrides:

newTopDocs in class TopDocsCollector<FieldValueHitQueue.Entry>

topDocs

public TopFieldDocs topDocs()

Description copied from class: TopDocsCollector

Returns the top docs that were collected by this collector.

Overrides:

topDocs in class TopDocsCollector<FieldValueHitQueue.Entry>

isEarlyTerminated

public boolean isEarlyTerminated()

Return whether collection terminated early.