Class IndexSearcher

Implements search over a single IndexReader.

Applications usually need only call the inherited Search(Query, int) or Search(Query, Filter?, int) methods. For performance reasons, if your index is unchanging, you should share a single IndexSearcher instance across multiple searches instead of creating a new one per-search. If your index has changed and you wish to see the changes reflected in searching, you should use OpenIfChanged(DirectoryReader) to obtain a new reader and then create a new IndexSearcher from that. Also, for low-latency turnaround it's best to use a near-real-time reader (Open(IndexWriter, bool)). Once you have a new IndexReader, it's relatively cheap to create a new IndexSearcher from it.

NOTE: IndexSearcher instances are completely thread safe, meaning multiple threads can call any of its methods, concurrently. If your application requires external synchronization, you should not synchronize on the IndexSearcher instance; use your own (non-Lucene) objects instead.

Inheritance

object

IndexSearcher

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

Namespace: Lucene.Net.Search

Assembly: Lucene.Net.dll

Syntax

public class IndexSearcher

Constructors

IndexSearcher(IndexReader)

Creates a searcher searching the provided index.

Declaration

public IndexSearcher(IndexReader r)

Parameters

Type	Name	Description
IndexReader	r

Exceptions

Type	Condition
ArgumentNullException	r is null.

IndexSearcher(IndexReader, TaskScheduler?)

Runs searches for each segment separately, using the provided TaskScheduler. IndexSearcher will not shutdown/awaitTermination this TaskScheduler on dispose; you must do so, eventually, on your own.

Note

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

Declaration

public IndexSearcher(IndexReader r, TaskScheduler? executor)

Parameters

Type	Name	Description
IndexReader	r
TaskScheduler	executor

Exceptions

Type	Condition
ArgumentNullException	r is null.

IndexSearcher(IndexReaderContext)

Creates a searcher searching the provided top-level IndexReaderContext.

Note

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

Declaration

public IndexSearcher(IndexReaderContext context)

Parameters

Type	Name	Description
IndexReaderContext	context

Exceptions

Type	Condition
ArgumentNullException	context is null.

See Also

IndexReaderContext

Context

IndexSearcher(IndexReaderContext, TaskScheduler?)

Creates a searcher searching the provided top-level IndexReaderContext.

Given a non-nullTaskScheduler this method runs searches for each segment separately, using the provided TaskScheduler. IndexSearcher will not shutdown/awaitTermination this TaskScheduler on close; you must do so, eventually, on your own.

Note

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

Declaration

public IndexSearcher(IndexReaderContext context, TaskScheduler? executor)

Parameters

Type	Name	Description
IndexReaderContext	context
TaskScheduler	executor

Exceptions

Type	Condition
ArgumentNullException	context is null.

See Also

IndexReaderContext

Context

IndexSearcher(IndexReaderContext, TaskScheduler?, bool)

LUCENENET specific constructor that can be used by the subclasses to control whether the leaf slices are allocated in the base class or subclass.

Declaration

protected IndexSearcher(IndexReaderContext context, TaskScheduler? executor, bool allocateLeafSlices)

Parameters

Type	Name	Description
IndexReaderContext	context
TaskScheduler	executor
bool	allocateLeafSlices

Remarks

If executor is non-null and you choose to skip allocating the leaf slices (i.e. allocateLeafSlices == false), you must set the m_leafSlices field in your subclass constructor. This is commonly done by calling GetSlices(IList<AtomicReaderContext>) and using the result to set m_leafSlices. You may wish to do this if you have state to pass into your constructor and need to set it prior to the call to GetSlices(IList<AtomicReaderContext>) so it is available for use as a member field or property inside a custom override of GetSlices(IList<AtomicReaderContext>).

Exceptions

Type	Condition
ArgumentNullException	context is null.

Fields

m_leafContexts

Implements search over a single IndexReader.

Applications usually need only call the inherited Search(Query, int) or Search(Query, Filter?, int) methods. For performance reasons, if your index is unchanging, you should share a single IndexSearcher instance across multiple searches instead of creating a new one per-search. If your index has changed and you wish to see the changes reflected in searching, you should use OpenIfChanged(DirectoryReader) to obtain a new reader and then create a new IndexSearcher from that. Also, for low-latency turnaround it's best to use a near-real-time reader (Open(IndexWriter, bool)). Once you have a new IndexReader, it's relatively cheap to create a new IndexSearcher from it.

NOTE: IndexSearcher instances are completely thread safe, meaning multiple threads can call any of its methods, concurrently. If your application requires external synchronization, you should not synchronize on the IndexSearcher instance; use your own (non-Lucene) objects instead.

Declaration

protected readonly IList<AtomicReaderContext> m_leafContexts

Field Value

Type	Description
IList<AtomicReaderContext>

m_leafSlices

Used with executor - each slice holds a set of leafs executed within one thread

Declaration

protected readonly IndexSearcher.LeafSlice[]? m_leafSlices

Field Value

Type	Description
LeafSlice[]

m_readerContext

Implements search over a single IndexReader.

Applications usually need only call the inherited Search(Query, int) or Search(Query, Filter?, int) methods. For performance reasons, if your index is unchanging, you should share a single IndexSearcher instance across multiple searches instead of creating a new one per-search. If your index has changed and you wish to see the changes reflected in searching, you should use OpenIfChanged(DirectoryReader) to obtain a new reader and then create a new IndexSearcher from that. Also, for low-latency turnaround it's best to use a near-real-time reader (Open(IndexWriter, bool)). Once you have a new IndexReader, it's relatively cheap to create a new IndexSearcher from it.

NOTE: IndexSearcher instances are completely thread safe, meaning multiple threads can call any of its methods, concurrently. If your application requires external synchronization, you should not synchronize on the IndexSearcher instance; use your own (non-Lucene) objects instead.

Declaration

protected readonly IndexReaderContext m_readerContext

Field Value

Type	Description
IndexReaderContext

Properties

DefaultSimilarity

Expert: returns a default Similarity instance. In general, this method is only called to initialize searchers and writers. User code and query implementations should respect Similarity.

Note

This API is for internal purposes only and might change in incompatible ways in the next release.

Declaration

public static Similarity DefaultSimilarity { get; }

Property Value

Type	Description
Similarity

IndexReader

Return the IndexReader this searches.

Declaration

public virtual IndexReader IndexReader { get; }

Property Value

Type	Description
IndexReader

Similarity

Expert: Set the Similarity implementation used by this IndexSearcher.

Declaration

public virtual Similarity Similarity { get; set; }

Property Value

Type	Description
Similarity

TopReaderContext

Returns this searchers the top-level IndexReaderContext.

Declaration

public virtual IndexReaderContext TopReaderContext { get; }

Property Value

Type	Description
IndexReaderContext

See Also

Context

Methods

CollectionStatistics(string)

Returns CollectionStatistics for a field.

This can be overridden for example, to return a field's statistics across a distributed collection.

Note

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

Declaration

public virtual CollectionStatistics CollectionStatistics(string field)

Parameters

Type	Name	Description
string	field

Returns

Type	Description
CollectionStatistics

CreateNormalizedWeight(Query)

Creates a normalized weight for a top-level Query. The query is rewritten by this method and CreateWeight(IndexSearcher) called, afterwards the Weight is normalized. The returned Weight can then directly be used to get a Scorer.

Note

This API is for internal purposes only and might change in incompatible ways in the next release.

Declaration

public virtual Weight CreateNormalizedWeight(Query query)

Parameters

Type	Name	Description
Query	query

Returns

Type	Description
Weight

Exceptions

Type	Condition
ArgumentNullException	query is null.

Doc(int)

Sugar for

.IndexReader.Document(docID)

Declaration

public virtual Document Doc(int docID)

Parameters

Type	Name	Description
int	docID

Returns

Type	Description
Document

See Also

Document(int)

Doc(int, StoredFieldVisitor)

Sugar for

.IndexReader.Document(docID, fieldVisitor)

Declaration

public virtual void Doc(int docID, StoredFieldVisitor fieldVisitor)

Parameters

Type	Name	Description
int	docID
StoredFieldVisitor	fieldVisitor

Exceptions

Type	Condition
ArgumentNullException	fieldVisitor is null.

See Also

Document(int, StoredFieldVisitor)

Doc(int, ISet<string>?)

Sugar for

.IndexReader.Document(docID, fieldsToLoad)

Declaration

public virtual Document Doc(int docID, ISet<string>? fieldsToLoad)

Parameters

Type	Name	Description
int	docID
ISet<string>	fieldsToLoad

Returns

Type	Description
Document

See Also

Document(int, ISet<string>)

Document(int, ISet<string>)

Implements search over a single IndexReader.

Applications usually need only call the inherited Search(Query, int) or Search(Query, Filter?, int) methods. For performance reasons, if your index is unchanging, you should share a single IndexSearcher instance across multiple searches instead of creating a new one per-search. If your index has changed and you wish to see the changes reflected in searching, you should use OpenIfChanged(DirectoryReader) to obtain a new reader and then create a new IndexSearcher from that. Also, for low-latency turnaround it's best to use a near-real-time reader (Open(IndexWriter, bool)). Once you have a new IndexReader, it's relatively cheap to create a new IndexSearcher from it.

NOTE: IndexSearcher instances are completely thread safe, meaning multiple threads can call any of its methods, concurrently. If your application requires external synchronization, you should not synchronize on the IndexSearcher instance; use your own (non-Lucene) objects instead.

Declaration

[Obsolete("Use <seealso cref=#doc(int, java.util.Set)/> instead.")]
public Document Document(int docID, ISet<string> fieldsToLoad)

Parameters

Type	Name	Description
int	docID
ISet<string>	fieldsToLoad

Returns

Type	Description
Document

Explain(Query, int)

Returns an Explanation that describes how doc scored against query.

This is intended to be used in developing Similarity implementations, and, for good performance, should not be displayed with every hit. Computing an explanation is as expensive as executing the query over the entire index.

Declaration

public virtual Explanation Explain(Query query, int doc)

Parameters

Type	Name	Description
Query	query
int	doc

Returns

Type	Description
Explanation

Exceptions

Type	Condition
ArgumentNullException	query is null.

Explain(Weight, int)

Expert: low-level implementation method Returns an Explanation that describes how doc scored against weight.

This is intended to be used in developing Similarity implementations, and, for good performance, should not be displayed with every hit. Computing an explanation is as expensive as executing the query over the entire index.

Applications should call Explain(Query, int).

Declaration

protected virtual Explanation Explain(Weight weight, int doc)

Parameters

Type	Name	Description
Weight	weight
int	doc

Returns

Type	Description
Explanation

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	weight is null.

GetSlices(IList<AtomicReaderContext>)

Expert: Creates an array of leaf slices each holding a subset of the given leaves. Each IndexSearcher.LeafSlice is executed in a single thread. By default there will be one IndexSearcher.LeafSlice per leaf (AtomicReaderContext).

Declaration

protected virtual IndexSearcher.LeafSlice[] GetSlices(IList<AtomicReaderContext> leaves)

Parameters

Type	Name	Description
IList<AtomicReaderContext>	leaves

Returns

Type	Description
LeafSlice[]

Exceptions

Type	Condition
ArgumentNullException	leaves is null.

Rewrite(Query)

Expert: called to re-write queries into primitive queries.

Declaration

public virtual Query Rewrite(Query query)

Parameters

Type	Name	Description
Query	query

Returns

Type	Description
Query

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	query is null.

Search(Query, Filter?, ICollector)

Lower-level search API.

Collect(int) is called for every matching document.

Declaration

public virtual void Search(Query query, Filter? filter, ICollector results)

Parameters

Type	Name	Description
Query	query	To match documents
Filter	filter	Ef non-null, used to permit documents to be collected.
ICollector	results	To receive hits

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	query or results is null.

Search(Query, Filter?, int)

Finds the top n hits for query, applying filter if non-null.

Declaration

public virtual TopDocs Search(Query query, Filter? filter, int n)

Parameters

Type	Name	Description
Query	query
Filter	filter
int	n

Returns

Type	Description
TopDocs

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.

Search(Query, Filter?, int, Sort)

Search implementation with arbitrary sorting. Finds the top n hits for query, applying filter if non-null, and sorting the hits by the criteria in sort.

NOTE: this does not compute scores by default; use Search(Query, Filter?, int, Sort, bool, bool) to control scoring.

Declaration

public virtual TopFieldDocs Search(Query query, Filter? filter, int n, Sort sort)

Parameters

Type	Name	Description
Query	query
Filter	filter
int	n
Sort	sort

Returns

Type	Description
TopFieldDocs

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	query or sort is null.

Search(Query, Filter?, int, Sort, bool, bool)

Search implementation with arbitrary sorting, plus control over whether hit scores and max score should be computed. Finds the top n hits for query, applying filter if non-null, and sorting the hits by the criteria in sort. If doDocScores is true then the score of each hit will be computed and returned. If doMaxScore is true then the maximum score over all collected hits will be computed.

Declaration

public virtual TopFieldDocs Search(Query query, Filter? filter, int n, Sort sort, bool doDocScores, bool doMaxScore)

Parameters

Type	Name	Description
Query	query
Filter	filter
int	n
Sort	sort
bool	doDocScores
bool	doMaxScore

Returns

Type	Description
TopFieldDocs

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	query or sort is null.

Search(Query, ICollector)

Lower-level search API.

Collect(int) is called for every matching document.

Declaration

public virtual void Search(Query query, ICollector results)

Parameters

Type	Name	Description
Query	query
ICollector	results

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	query or results is null.

Search(Query, int)

Finds the top n hits for query.

Declaration

public virtual TopDocs Search(Query query, int n)

Parameters

Type	Name	Description
Query	query
int	n

Returns

Type	Description
TopDocs

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	query is null.

Search(Query, int, Sort)

Search implementation with arbitrary sorting and no filter.

Declaration

public virtual TopFieldDocs Search(Query query, int n, Sort sort)

Parameters

Type	Name	Description
Query	query	The query to search for
int	n	Return only the top n results
Sort	sort	The Sort object

Returns

Type	Description
TopFieldDocs	The top docs, sorted according to the supplied Sort instance

Exceptions

Type	Condition
IOException	if there is a low-level I/O error
ArgumentNullException	query or sort is null.

Search(Weight, FieldDoc?, int, Sort, bool, bool, bool)

Just like Search(Weight, int, Sort, bool, bool), but you choose whether or not the fields in the returned FieldDoc instances should be set by specifying fillFields.

Declaration

protected virtual TopFieldDocs Search(Weight weight, FieldDoc? after, int nDocs, Sort sort, bool fillFields, bool doDocScores, bool doMaxScore)

Parameters

Type	Name	Description
Weight	weight
FieldDoc	after
int	nDocs
Sort	sort
bool	fillFields
bool	doDocScores
bool	doMaxScore

Returns

Type	Description
TopFieldDocs

Exceptions

Type	Condition
ArgumentNullException	weight or sort is null.

Search(Weight, ScoreDoc?, int)

Expert: Low-level search implementation. Finds the top nDocs hits for query, applying filter if non-null.

Applications should usually call Search(Query, int) or Search(Query, Filter?, int) instead.

Declaration

protected virtual TopDocs Search(Weight weight, ScoreDoc? after, int nDocs)

Parameters

Type	Name	Description
Weight	weight
ScoreDoc	after
int	nDocs

Returns

Type	Description
TopDocs

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	weight is null.

Search(Weight, int, Sort, bool, bool)

Expert: Low-level search implementation with arbitrary sorting and control over whether hit scores and max score should be computed. Finds the top nDocs hits for query and sorting the hits by the criteria in sort.

Applications should usually call Search(Query, Filter?, int, Sort) instead.

Declaration

protected virtual TopFieldDocs Search(Weight weight, int nDocs, Sort sort, bool doDocScores, bool doMaxScore)

Parameters

Type	Name	Description
Weight	weight
int	nDocs
Sort	sort
bool	doDocScores
bool	doMaxScore

Returns

Type	Description
TopFieldDocs

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	weight or sort is null.

Search(IList<AtomicReaderContext>, Weight, FieldDoc?, int, Sort, bool, bool, bool)

Just like Search(Weight, int, Sort, bool, bool), but you choose whether or not the fields in the returned FieldDoc instances should be set by specifying fillFields.

Declaration

protected virtual TopFieldDocs Search(IList<AtomicReaderContext> leaves, Weight weight, FieldDoc? after, int nDocs, Sort sort, bool fillFields, bool doDocScores, bool doMaxScore)

Parameters

Type	Name	Description
IList<AtomicReaderContext>	leaves
Weight	weight
FieldDoc	after
int	nDocs
Sort	sort
bool	fillFields
bool	doDocScores
bool	doMaxScore

Returns

Type	Description
TopFieldDocs

Exceptions

Type	Condition
ArgumentNullException	leaves or weight is null.

Search(IList<AtomicReaderContext>, Weight, ICollector)

Lower-level search API.

Collect(int) is called for every document.

NOTE: this method executes the searches on all given leaves exclusively. To search across all the searchers leaves use m_leafContexts.

Declaration

protected virtual void Search(IList<AtomicReaderContext> leaves, Weight weight, ICollector collector)

Parameters

Type	Name	Description
IList<AtomicReaderContext>	leaves	The searchers leaves to execute the searches on
Weight	weight	To match documents
ICollector	collector	To receive hits

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	leaves, weight, or collector is null.

Search(IList<AtomicReaderContext>, Weight, ScoreDoc?, int)

Expert: Low-level search implementation. Finds the top

n

hits for query.

Applications should usually call Search(Query, int) or Search(Query, Filter?, int) instead.

Declaration

protected virtual TopDocs Search(IList<AtomicReaderContext> leaves, Weight weight, ScoreDoc? after, int nDocs)

Parameters

Type	Name	Description
IList<AtomicReaderContext>	leaves
Weight	weight
ScoreDoc	after
int	nDocs

Returns

Type	Description
TopDocs

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	leaves or weight is null.

SearchAfter(ScoreDoc?, Query, Filter?, int)

Finds the top n hits for query, applying filter if non-null, where all results are after a previous result (after).

By passing the bottom result from a previous page as after, this method can be used for efficient 'deep-paging' across potentially large result sets.

Declaration

public virtual TopDocs SearchAfter(ScoreDoc? after, Query query, Filter? filter, int n)

Parameters

Type	Name	Description
ScoreDoc	after
Query	query
Filter	filter
int	n

Returns

Type	Description
TopDocs

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	query is null.

SearchAfter(ScoreDoc?, Query, Filter?, int, Sort)

Finds the top n hits for query, applying filter if non-null, where all results are after a previous result (after).

By passing the bottom result from a previous page as after, this method can be used for efficient 'deep-paging' across potentially large result sets.

Declaration

public virtual TopDocs SearchAfter(ScoreDoc? after, Query query, Filter? filter, int n, Sort sort)

Parameters

Type	Name	Description
ScoreDoc	after
Query	query
Filter	filter
int	n
Sort	sort

Returns

Type	Description
TopDocs

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	query or sort is null.

SearchAfter(ScoreDoc?, Query, Filter?, int, Sort, bool, bool)

Finds the top n hits for query where all results are after a previous result (after), allowing control over whether hit scores and max score should be computed.

By passing the bottom result from a previous page as after, this method can be used for efficient 'deep-paging' across potentially large result sets. If doDocScores is true then the score of each hit will be computed and returned. If doMaxScore is true then the maximum score over all collected hits will be computed.

Declaration

public virtual TopDocs SearchAfter(ScoreDoc? after, Query query, Filter? filter, int n, Sort sort, bool doDocScores, bool doMaxScore)

Parameters

Type	Name	Description
ScoreDoc	after
Query	query
Filter	filter
int	n
Sort	sort
bool	doDocScores
bool	doMaxScore

Returns

Type	Description
TopDocs

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	query or sort is null.

SearchAfter(ScoreDoc?, Query, int)

Finds the top n hits for top query where all results are after a previous result (top after).

By passing the bottom result from a previous page as after, this method can be used for efficient 'deep-paging' across potentially large result sets.

Declaration

public virtual TopDocs SearchAfter(ScoreDoc? after, Query query, int n)

Parameters

Type	Name	Description
ScoreDoc	after
Query	query
int	n

Returns

Type	Description
TopDocs

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	query is null.

SearchAfter(ScoreDoc?, Query, int, Sort)

Finds the top n hits for query where all results are after a previous result (after).

By passing the bottom result from a previous page as after, this method can be used for efficient 'deep-paging' across potentially large result sets.

Declaration

public virtual TopDocs SearchAfter(ScoreDoc? after, Query query, int n, Sort sort)

Parameters

Type	Name	Description
ScoreDoc	after
Query	query
int	n
Sort	sort

Returns

Type	Description
TopDocs

Exceptions

Type	Condition
BooleanQuery.TooManyClausesException	If a query would exceed MaxClauseCount clauses.
ArgumentNullException	query or sort is null.

TermStatistics(Term, TermContext)

Returns TermStatistics for a term.

This can be overridden for example, to return a term's statistics across a distributed collection.

Note

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

Declaration

public virtual TermStatistics TermStatistics(Term term, TermContext context)

Parameters

Type	Name	Description
Term	term
TermContext	context

Returns

Type	Description
TermStatistics

Exceptions

Type	Condition
ArgumentNullException	term or context is null.

ToString()

Returns a string that represents the current object.

Declaration

public override string ToString()

Returns

Type	Description
string	A string that represents the current object.

Overrides

object.ToString()

WrapFilter(Query, Filter?)

Note

This API is for internal purposes only and might change in incompatible ways in the next release.

Declaration

protected virtual Query WrapFilter(Query query, Filter? filter)

Parameters

Type	Name	Description
Query	query
Filter	filter

Returns

Type	Description
Query

Exceptions

Type	Condition
ArgumentNullException	query is null.