Class IndexSearcher

Implements search over a single IndexReader.

Applications usually need only call the inherited Search(Query, Int32) or Search(Query, Filter, Int32) 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, Boolean)). 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

System.Object

IndexSearcher

Inherited Members

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

System.Object.ReferenceEquals(System.Object, System.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

IndexSearcher(IndexReader, TaskScheduler)

Runs searches for each segment separately, using the provided System.Threading.Tasks.TaskScheduler. IndexSearcher will not shutdown/awaitTermination this System.Threading.Tasks.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
System.Threading.Tasks.TaskScheduler	executor

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

See Also

IndexReaderContext

Context

IndexSearcher(IndexReaderContext, TaskScheduler)

Creates a searcher searching the provided top-level IndexReaderContext.

Given a non-null System.Threading.Tasks.TaskScheduler this method runs searches for each segment separately, using the provided System.Threading.Tasks.TaskScheduler. IndexSearcher will not shutdown/awaitTermination this System.Threading.Tasks.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
System.Threading.Tasks.TaskScheduler	executor

See Also

IndexReaderContext

Context

Fields

m_leafContexts

Declaration

protected readonly IList<AtomicReaderContext> m_leafContexts

Field Value

Type	Description
System.Collections.Generic.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
IndexSearcher.LeafSlice[]

m_readerContext

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
System.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

Doc(Int32)

Sugar for

.IndexReader.Document(docID)

Declaration

public virtual Document Doc(int docID)

Parameters

Type	Name	Description
System.Int32	docID

Returns

Type	Description
Document

See Also

Document(System.Int32)

Doc(Int32, StoredFieldVisitor)

Sugar for

.IndexReader.Document(docID, fieldVisitor)

Declaration

public virtual void Doc(int docID, StoredFieldVisitor fieldVisitor)

Parameters

Type	Name	Description
System.Int32	docID
StoredFieldVisitor	fieldVisitor

See Also

Document(System.Int32, StoredFieldVisitor)

Doc(Int32, ISet<String>)

Sugar for

.IndexReader.Document(docID, fieldsToLoad)

Declaration

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

Parameters

Type	Name	Description
System.Int32	docID
System.Collections.Generic.ISet<System.String>	fieldsToLoad

Returns

Type	Description
Document

See Also

Document(System.Int32, System.Collections.Generic.ISet<System.String>)

Document(Int32, ISet<String>)

Declaration

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

Parameters

Type	Name	Description
System.Int32	docID
System.Collections.Generic.ISet<System.String>	fieldsToLoad

Returns

Type	Description
Document

Explain(Query, Int32)

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
System.Int32	doc

Returns

Type	Description
Explanation

Explain(Weight, Int32)

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, Int32).

Declaration

protected virtual Explanation Explain(Weight weight, int doc)

Parameters

Type	Name	Description
Weight	weight
System.Int32	doc

Returns

Type	Description
Explanation

Exceptions

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

Rewrite(Query)

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

Declaration

public virtual Query Rewrite(Query original)

Parameters

Type	Name	Description
Query	original

Returns

Type	Description
Query

Exceptions

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

Search(Query, Filter, ICollector)

Lower-level search API.

Collect(Int32) 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.

Search(Query, Filter, Int32)

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
System.Int32	n

Returns

Type	Description
TopDocs

Exceptions

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

Search(Query, Filter, Int32, 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, Int32, Sort, Boolean, Boolean) to control scoring.

Declaration

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

Parameters

Type	Name	Description
Query	query
Filter	filter
System.Int32	n
Sort	sort

Returns

Type	Description
TopFieldDocs

Exceptions

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

Search(Query, Filter, Int32, Sort, Boolean, Boolean)

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
System.Int32	n
Sort	sort
System.Boolean	doDocScores
System.Boolean	doMaxScore

Returns

Type	Description
TopFieldDocs

Exceptions

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

Search(Query, ICollector)

Lower-level search API.

Collect(Int32) 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.

Search(Query, Int32)

Finds the top n hits for query.

Declaration

public virtual TopDocs Search(Query query, int n)

Parameters

Type	Name	Description
Query	query
System.Int32	n

Returns

Type	Description
TopDocs

Exceptions

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

Search(Query, Int32, 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
System.Int32	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
System.IO.IOException	if there is a low-level I/O error

Search(Weight, FieldDoc, Int32, Sort, Boolean, Boolean, Boolean)

Just like Search(Weight, Int32, Sort, Boolean, Boolean), 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
System.Int32	nDocs
Sort	sort
System.Boolean	fillFields
System.Boolean	doDocScores
System.Boolean	doMaxScore

Returns

Type	Description
TopFieldDocs

Search(Weight, ScoreDoc, Int32)

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

Applications should usually call Search(Query, Int32) or Search(Query, Filter, Int32) instead.

Declaration

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

Parameters

Type	Name	Description
Weight	weight
ScoreDoc	after
System.Int32	nDocs

Returns

Type	Description
TopDocs

Exceptions

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

Search(Weight, Int32, Sort, Boolean, Boolean)

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, Int32, Sort) instead.

Declaration

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

Parameters

Type	Name	Description
Weight	weight
System.Int32	nDocs
Sort	sort
System.Boolean	doDocScores
System.Boolean	doMaxScore

Returns

Type	Description
TopFieldDocs

Exceptions

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

Search(IList<AtomicReaderContext>, Weight, FieldDoc, Int32, Sort, Boolean, Boolean, Boolean)

Just like Search(Weight, Int32, Sort, Boolean, Boolean), 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
System.Collections.Generic.IList<AtomicReaderContext>	leaves
Weight	weight
FieldDoc	after
System.Int32	nDocs
Sort	sort
System.Boolean	fillFields
System.Boolean	doDocScores
System.Boolean	doMaxScore

Returns

Type	Description
TopFieldDocs

Search(IList<AtomicReaderContext>, Weight, ICollector)

Lower-level search API.

Collect(Int32) 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
System.Collections.Generic.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.

Search(IList<AtomicReaderContext>, Weight, ScoreDoc, Int32)

Expert: Low-level search implementation. Finds the top

n

hits for query.

Applications should usually call Search(Query, Int32) or Search(Query, Filter, Int32) instead.

Declaration

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

Parameters

Type	Name	Description
System.Collections.Generic.IList<AtomicReaderContext>	leaves
Weight	weight
ScoreDoc	after
System.Int32	nDocs

Returns

Type	Description
TopDocs

Exceptions

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

SearchAfter(ScoreDoc, Query, Filter, Int32)

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
System.Int32	n

Returns

Type	Description
TopDocs

Exceptions

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

SearchAfter(ScoreDoc, Query, Filter, Int32, 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
System.Int32	n
Sort	sort

Returns

Type	Description
TopDocs

Exceptions

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

SearchAfter(ScoreDoc, Query, Filter, Int32, Sort, Boolean, Boolean)

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
System.Int32	n
Sort	sort
System.Boolean	doDocScores
System.Boolean	doMaxScore

Returns

Type	Description
TopDocs

Exceptions

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

SearchAfter(ScoreDoc, Query, Int32)

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
System.Int32	n

Returns

Type	Description
TopDocs

Exceptions

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

SearchAfter(ScoreDoc, Query, Int32, 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
System.Int32	n
Sort	sort

Returns

Type	Description
TopDocs

Exceptions

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

Slices(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[] Slices(IList<AtomicReaderContext> leaves)

Parameters

Type	Name	Description
System.Collections.Generic.IList<AtomicReaderContext>	leaves

Returns

Type	Description
IndexSearcher.LeafSlice[]

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

ToString()

Declaration

public override string ToString()

Returns

Type	Description
System.String

Overrides

System.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