Class TopFieldCollector

A ICollector that sorts by SortField using FieldComparers.

See the Create(Sort, int, bool, bool, bool, bool) method for instantiating a TopFieldCollector.

Note

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

Inheritance
object
TopDocsCollector<FieldValueHitQueue.Entry>
TopFieldCollector
Inherited Members
Namespace: Lucene.Net.Search
Assembly: Lucene.Net.dll
Syntax
public abstract class TopFieldCollector : TopDocsCollector<FieldValueHitQueue.Entry>, ITopDocsCollector, ICollector

Properties

AcceptsDocsOutOfOrder

Return true if this collector does not require the matching docIDs to be delivered in int sort order (smallest to largest) to Collect(int).

Most Lucene Query implementations will visit matching docIDs in order. However, some queries (currently limited to certain cases of BooleanQuery) can achieve faster searching if the ICollector allows them to deliver the docIDs out of order.

Many collectors don't mind getting docIDs out of order, so it's important to return true here.

Declaration
public override bool AcceptsDocsOutOfOrder { get; }
Property Value
Type Description
bool
Overrides

Methods

Create(Sort, int, FieldDoc?, bool, bool, bool, bool)

Creates a new TopFieldCollector from the given arguments.

NOTE: The instances returned by this method pre-allocate a full array of length numHits.
Declaration
public static TopFieldCollector Create(Sort sort, int numHits, FieldDoc? after, bool fillFields, bool trackDocScores, bool trackMaxScore, bool docsScoredInOrder)
Parameters
Type Name Description
Sort sort

The sort criteria (SortFields).
int numHits

The number of results to collect.
FieldDoc after

Only hits after this FieldDoc will be collected
bool fillFields

Specifies whether the actual field values should be returned on the results (FieldDoc).
bool trackDocScores

Specifies whether document scores should be tracked and set on the results. Note that if set to false, then the results' scores will be set to NaN. Setting this to true affects performance, as it incurs the score computation on each competitive result. Therefore if document scores are not required by the application, it is recommended to set it to false.
bool trackMaxScore

Specifies whether the query's maxScore should be tracked and set on the resulting TopDocs. Note that if set to false, MaxScore returns NaN. Setting this to true affects performance as it incurs the score computation on each result. Also, setting this true automatically sets trackDocScores to true as well.
bool docsScoredInOrder

Specifies whether documents are scored in doc Id order or not by the given Scorer in SetScorer(Scorer).
Returns
Type Description
TopFieldCollector

A TopFieldCollector instance which will sort the results by the sort criteria.
Exceptions
Type Condition
IOException

If there is a low-level I/O error
ArgumentNullException

sort is null.

Create(Sort, int, bool, bool, bool, bool)

Creates a new TopFieldCollector from the given arguments.

NOTE: The instances returned by this method pre-allocate a full array of length numHits.
Declaration
public static TopFieldCollector Create(Sort sort, int numHits, bool fillFields, bool trackDocScores, bool trackMaxScore, bool docsScoredInOrder)
Parameters
Type Name Description
Sort sort

The sort criteria (SortFields).
int numHits

The number of results to collect.
bool fillFields

Specifies whether the actual field values should be returned on the results (FieldDoc).
bool trackDocScores

Specifies whether document scores should be tracked and set on the results. Note that if set to false, then the results' scores will be set to NaN. Setting this to true affects performance, as it incurs the score computation on each competitive result. Therefore if document scores are not required by the application, it is recommended to set it to false.
bool trackMaxScore

Specifies whether the query's maxScore should be tracked and set on the resulting TopDocs. Note that if set to false, MaxScore returns NaN. Setting this to true affects performance as it incurs the score computation on each result. Also, setting this true automatically sets trackDocScores to true as well.
bool docsScoredInOrder

Specifies whether documents are scored in doc Id order or not by the given Scorer in SetScorer(Scorer).
Returns
Type Description
TopFieldCollector

A TopFieldCollector instance which will sort the results by the sort criteria.
Exceptions
Type Condition
IOException

If there is a low-level I/O error
ArgumentNullException

sort is null.

NewTopDocs(ScoreDoc[]?, int)

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(int) or because the arguments to TopDocs were invalid.

Declaration
protected override TopDocs NewTopDocs(ScoreDoc[]? results, int start)
Parameters
Type Name Description
ScoreDoc[] results
int start
Returns
Type Description
TopDocs
Overrides

PopulateResults(ScoreDoc[], int)

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

Declaration
protected override void PopulateResults(ScoreDoc[] results, int howMany)
Parameters
Type Name Description
ScoreDoc[] results
int howMany
Overrides

Implements