Package org.apache.lucene.queries
Class BlendedTermQuery
- java.lang.Object
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- org.apache.lucene.search.Query
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- org.apache.lucene.queries.BlendedTermQuery
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public abstract class BlendedTermQuery extends org.apache.lucene.search.Query
BlendedTermQuery can be used to unify term statistics across one or more fields in the index. A common problem with structured documents is that a term that is significant in on field might not be significant in other fields like in a scenario where documents represent users with a "first_name" and a "second_name". When someone searches for "simon" it will very likely get "paul simon" first since "simon" is a an uncommon last name ie. has a low document frequency. This query tries to "lie" about the global statistics like document frequency as well total term frequency to rank based on the estimated statistics.While aggregating the total term frequency is trivial since it can be summed up not every
Similarity
makes use of this statistic. The document frequency which is used in theClassicSimilarity
can only be estimated as an lower-bound since it is a document based statistic. For the document frequency the maximum frequency across all fields per term is used which is the minimum number of documents the terms occurs in.
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Constructor Summary
Constructors Constructor Description BlendedTermQuery(org.apache.lucene.index.Term[] terms, float[] boosts)
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description protected void
blend(org.apache.lucene.index.TermContext[] contexts, int maxDoc, org.apache.lucene.index.IndexReader reader)
static BlendedTermQuery
commonTermsBlendedQuery(org.apache.lucene.index.Term[] terms, float[] boosts, float maxTermFrequency)
static BlendedTermQuery
dismaxBlendedQuery(org.apache.lucene.index.Term[] terms, float tieBreakerMultiplier)
static BlendedTermQuery
dismaxBlendedQuery(org.apache.lucene.index.Term[] terms, float[] boosts, float tieBreakerMultiplier)
boolean
equals(java.lang.Object o)
java.util.List<org.apache.lucene.index.Term>
getTerms()
int
hashCode()
org.apache.lucene.search.Query
rewrite(org.apache.lucene.index.IndexReader reader)
protected abstract org.apache.lucene.search.Query
topLevelQuery(org.apache.lucene.index.Term[] terms, org.apache.lucene.index.TermContext[] ctx, int[] docFreqs, int maxDoc)
java.lang.String
toString(java.lang.String field)
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Method Detail
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rewrite
public org.apache.lucene.search.Query rewrite(org.apache.lucene.index.IndexReader reader) throws java.io.IOException
- Overrides:
rewrite
in classorg.apache.lucene.search.Query
- Throws:
java.io.IOException
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topLevelQuery
protected abstract org.apache.lucene.search.Query topLevelQuery(org.apache.lucene.index.Term[] terms, org.apache.lucene.index.TermContext[] ctx, int[] docFreqs, int maxDoc)
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blend
protected void blend(org.apache.lucene.index.TermContext[] contexts, int maxDoc, org.apache.lucene.index.IndexReader reader) throws java.io.IOException
- Throws:
java.io.IOException
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getTerms
public java.util.List<org.apache.lucene.index.Term> getTerms()
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toString
public java.lang.String toString(java.lang.String field)
- Specified by:
toString
in classorg.apache.lucene.search.Query
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equals
public boolean equals(java.lang.Object o)
- Specified by:
equals
in classorg.apache.lucene.search.Query
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hashCode
public int hashCode()
- Specified by:
hashCode
in classorg.apache.lucene.search.Query
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commonTermsBlendedQuery
public static BlendedTermQuery commonTermsBlendedQuery(org.apache.lucene.index.Term[] terms, float[] boosts, float maxTermFrequency)
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dismaxBlendedQuery
public static BlendedTermQuery dismaxBlendedQuery(org.apache.lucene.index.Term[] terms, float tieBreakerMultiplier)
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dismaxBlendedQuery
public static BlendedTermQuery dismaxBlendedQuery(org.apache.lucene.index.Term[] terms, float[] boosts, float tieBreakerMultiplier)
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