C# Класс Lucene.Net.Queries.CommonTermsQuery

A query that executes high-frequency terms in a optional sub-query to prevent slow queries due to "common" terms like stopwords. This query builds 2 queries off the #add(Term) added terms: low-frequency terms are added to a required boolean clause and high-frequency terms are added to an optional boolean clause. The optional clause is only executed if the required "low-frequency" clause matches. Scores produced by this query will be slightly different than plain BooleanQuery scorer mainly due to differences in the Similarity#coord(int,int) number of leaf queries in the required boolean clause. In most cases, high-frequency terms are unlikely to significantly contribute to the document score unless at least one of the low-frequency terms are matched. This query can improve query execution times significantly if applicable.

CommonTermsQuery has several advantages over stopword filtering at index or query time since a term can be "classified" based on the actual document frequency in the index and can prevent slow queries even across domains without specialized stopword files.

Note: if the query only contains high-frequency terms the query is rewritten into a plain conjunction query ie. all high-frequency terms need to match in order to match a document.

Наследование: Lucene.Net.Search.Query

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Защищенные свойства (Protected)

Свойство	Тип	Описание
disableCoord	bool
highFreqBoost	float
highFreqOccur	Lucene.Net.Search.BooleanClause.Occur
lowFreqBoost	float
lowFreqOccur	Lucene.Net.Search.BooleanClause.Occur
maxTermFrequency	float
terms	IList

Открытые методы

Метод	Описание
Add ( Lucene.Net.Index.Term term ) : void	Adds a term to the CommonTermsQuery
CollectTermContext ( IndexReader reader, IList leaves, TermContext contextArray, Lucene.Net.Index.Term queryTerms ) : void
CommonTermsQuery ( BooleanClause highFreqOccur, BooleanClause lowFreqOccur, float maxTermFrequency ) : System	Creates a new CommonTermsQuery
CommonTermsQuery ( BooleanClause highFreqOccur, BooleanClause lowFreqOccur, float maxTermFrequency, bool disableCoord ) : System	Creates a new CommonTermsQuery
Equals ( object obj ) : bool
ExtractTerms ( ISet terms ) : void
GetHashCode ( ) : int
Rewrite ( IndexReader reader ) : Query
ToString ( string field ) : string

Защищенные методы

Метод	Описание
BuildQuery ( int maxDoc, TermContext contextArray, Lucene.Net.Index.Term queryTerms ) : Query
CalcHighFreqMinimumNumberShouldMatch ( int numOptional ) : int
CalcLowFreqMinimumNumberShouldMatch ( int numOptional ) : int
NewTermQuery ( Lucene.Net.Index.Term term, TermContext context ) : Query	Builds a new TermQuery instance. This is intended for subclasses that wish to customize the generated queries.

Приватные методы

Метод	Описание
MinNrShouldMatch ( float minNrShouldMatch, int numOptional ) : int

Описание методов

Add() публичный Метод

Adds a term to the CommonTermsQuery

public Add ( Lucene.Net.Index.Term term ) : void
term	Lucene.Net.Index.Term	/// the term to add
Результат	void

BuildQuery() защищенный Метод

protected BuildQuery ( int maxDoc, TermContext contextArray, Lucene.Net.Index.Term queryTerms ) : Query
maxDoc	int
contextArray	Lucene.Net.Index.TermContext
queryTerms	Lucene.Net.Index.Term
Результат	Lucene.Net.Search.Query

CalcHighFreqMinimumNumberShouldMatch() защищенный Метод

protected CalcHighFreqMinimumNumberShouldMatch ( int numOptional ) : int
numOptional	int
Результат	int

CalcLowFreqMinimumNumberShouldMatch() защищенный Метод

protected CalcLowFreqMinimumNumberShouldMatch ( int numOptional ) : int
numOptional	int
Результат	int

CollectTermContext() публичный Метод

public CollectTermContext ( IndexReader reader, IList leaves, TermContext contextArray, Lucene.Net.Index.Term queryTerms ) : void
reader	Lucene.Net.Index.IndexReader
leaves	IList
contextArray	Lucene.Net.Index.TermContext
queryTerms	Lucene.Net.Index.Term
Результат	void

CommonTermsQuery() публичный Метод

Creates a new CommonTermsQuery

/// if is pass as lowFreqOccur or /// highFreqOccur

public CommonTermsQuery ( BooleanClause highFreqOccur, BooleanClause lowFreqOccur, float maxTermFrequency ) : System
highFreqOccur	Lucene.Net.Search.BooleanClause	/// used for high frequency terms
lowFreqOccur	Lucene.Net.Search.BooleanClause	/// used for low frequency terms
maxTermFrequency	float	/// a value in [0..1) (or absolute number >=1) representing the /// maximum threshold of a terms document frequency to be considered a /// low frequency term.
Результат	System

CommonTermsQuery() публичный Метод

Creates a new CommonTermsQuery

/// if is pass as lowFreqOccur or /// highFreqOccur

public CommonTermsQuery ( BooleanClause highFreqOccur, BooleanClause lowFreqOccur, float maxTermFrequency, bool disableCoord ) : System
highFreqOccur	Lucene.Net.Search.BooleanClause	/// used for high frequency terms
lowFreqOccur	Lucene.Net.Search.BooleanClause	/// used for low frequency terms
maxTermFrequency	float	/// a value in [0..1) (or absolute number >=1) representing the /// maximum threshold of a terms document frequency to be considered a /// low frequency term.
disableCoord	bool	/// disables in scoring for the low /// / high frequency sub-queries
Результат	System

Equals() публичный Метод

public Equals ( object obj ) : bool
obj	object
Результат	bool

ExtractTerms() публичный Метод

public ExtractTerms ( ISet terms ) : void
terms	ISet
Результат	void

GetHashCode() публичный Метод

public GetHashCode ( ) : int
Результат	int

NewTermQuery() защищенный Метод

Builds a new TermQuery instance.

This is intended for subclasses that wish to customize the generated queries.

protected NewTermQuery ( Lucene.Net.Index.Term term, TermContext context ) : Query
term	Lucene.Net.Index.Term	term
context	Lucene.Net.Index.TermContext	the TermContext to be used to create the low level term query. Can be `null`.
Результат	Lucene.Net.Search.Query

Rewrite() публичный Метод

public Rewrite ( IndexReader reader ) : Query
reader	Lucene.Net.Index.IndexReader
Результат	Lucene.Net.Search.Query

ToString() публичный Метод

public ToString ( string field ) : string
field	string
Результат	string

Описание свойств

disableCoord защищенное свойство

protected bool disableCoord
Результат	bool

highFreqBoost защищенное свойство

protected float highFreqBoost
Результат	float

highFreqOccur защищенное свойство

protected BooleanClause.Occur,Lucene.Net.Search highFreqOccur
Результат	Lucene.Net.Search.BooleanClause.Occur

lowFreqBoost защищенное свойство

protected float lowFreqBoost
Результат	float

lowFreqOccur защищенное свойство

protected BooleanClause.Occur,Lucene.Net.Search lowFreqOccur
Результат	Lucene.Net.Search.BooleanClause.Occur

maxTermFrequency защищенное свойство

protected float maxTermFrequency
Результат	float

terms защищенное свойство

protected IList terms
Результат	IList