org.apache.lucene.search

Class MultiTermQuery.TopTermsBlendedFreqScoringRewrite

java.lang.Object

org.apache.lucene.search.MultiTermQuery.RewriteMethod

org.apache.lucene.search.TopTermsRewrite<BlendedTermQuery.Builder>

org.apache.lucene.search.MultiTermQuery.TopTermsBlendedFreqScoringRewrite

Enclosing class:

MultiTermQuery

public static final class MultiTermQuery.TopTermsBlendedFreqScoringRewrite
extends TopTermsRewrite<BlendedTermQuery.Builder>

A rewrite method that first translates each term into BooleanClause.Occur.SHOULD clause in a BooleanQuery, but adjusts the frequencies used for scoring to be blended across the terms, otherwise the rarest term typically ranks highest (often not useful eg in the set of expanded terms in a FuzzyQuery).

This rewrite method only uses the top scoring terms so it will not overflow the boolean max clause count.

See Also:

MultiTermQuery.setRewriteMethod(org.apache.lucene.search.MultiTermQuery.RewriteMethod)

Constructor Summary

Constructors

Constructor and Description
TopTermsBlendedFreqScoringRewrite(int size) Create a TopTermsBlendedScoringBooleanQueryRewrite for at most size terms.

Method Summary

Modifier and Type	Method and Description
protected void	addClause(BlendedTermQuery.Builder topLevel, Term term, int docCount, float boost, TermStates states)
protected void	addClause(B topLevel, Term term, int docCount, float boost) Add a MultiTermQuery term to the top-level query builder.
protected Query	build(BlendedTermQuery.Builder builder) Finalize the creation of the query from the builder.
protected int	getMaxSize() return the maximum size of the priority queue (for boolean rewrites this is BooleanQuery#getMaxClauseCount).
protected BlendedTermQuery.Builder	getTopLevelBuilder() Return a suitable builder for the top-level Query for holding all expanded terms.

Methods inherited from class org.apache.lucene.search.TopTermsRewrite

equals, getSize, hashCode, rewrite

Methods inherited from class org.apache.lucene.search.MultiTermQuery.RewriteMethod

getTermsEnum

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TopTermsBlendedFreqScoringRewrite

public TopTermsBlendedFreqScoringRewrite(int size)

Create a TopTermsBlendedScoringBooleanQueryRewrite for at most size terms.

NOTE: if BooleanQuery.getMaxClauseCount() is smaller than size, then it will be used instead.

Method Detail

getMaxSize

protected int getMaxSize()

Description copied from class: TopTermsRewrite

return the maximum size of the priority queue (for boolean rewrites this is BooleanQuery#getMaxClauseCount).

Specified by:

getMaxSize in class TopTermsRewrite<BlendedTermQuery.Builder>

getTopLevelBuilder

protected BlendedTermQuery.Builder getTopLevelBuilder()

Return a suitable builder for the top-level Query for holding all expanded terms.

build

protected Query build(BlendedTermQuery.Builder builder)

Finalize the creation of the query from the builder.

addClause

protected void addClause(BlendedTermQuery.Builder topLevel,
                         Term term,
                         int docCount,
                         float boost,
                         TermStates states)

addClause

protected final void addClause(B topLevel,
                               Term term,
                               int docCount,
                               float boost)
                        throws IOException

Add a MultiTermQuery term to the top-level query builder.

Throws:

IOException