Package org.apache.lucene.search
Class BlendedTermQuery
java.lang.Object
org.apache.lucene.search.Query
org.apache.lucene.search.BlendedTermQuery
A
Query
that blends index statistics across multiple terms. This is particularly useful
when several terms should produce identical scores, regardless of their index statistics.
For instance imagine that you are resolving synonyms at search time, all terms should produce identical scores instead of the default behavior, which tends to give higher scores to rare terms.
An other useful use-case is cross-field search: imagine that you would like to search for
john
on two fields: first_name
and last_name
. You might not want to give
a higher weight to matches on the field where john
is rarer, in which case BlendedTermQuery
would help as well.
- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Nested Class Summary
Modifier and TypeClassDescriptionstatic class
A Builder forBlendedTermQuery
.static class
ABlendedTermQuery.RewriteMethod
that creates aDisjunctionMaxQuery
out of the sub queries.static class
ABlendedTermQuery.RewriteMethod
defines how queries for individual terms should be merged. -
Field Summary
Modifier and TypeFieldDescriptionstatic final BlendedTermQuery.RewriteMethod
ABlendedTermQuery.RewriteMethod
that adds all sub queries to aBooleanQuery
.static final BlendedTermQuery.RewriteMethod
BlendedTermQuery.DisjunctionMaxRewrite
instance with a tie-breaker of0.01
. -
Method Summary
Modifier and TypeMethodDescriptionboolean
Override and implement query instance equivalence properly in a subclass.int
hashCode()
Override and implement query hash code properly in a subclass.final Query
rewrite
(IndexReader reader) Expert: called to re-write queries into primitive queries.Prints a query to a string, withfield
assumed to be the default field and omitted.void
visit
(QueryVisitor visitor) Recurse through the query tree, visiting any child queriesMethods inherited from class org.apache.lucene.search.Query
classHash, createWeight, sameClassAs, toString
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Field Details
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BOOLEAN_REWRITE
ABlendedTermQuery.RewriteMethod
that adds all sub queries to aBooleanQuery
. ThisBlendedTermQuery.RewriteMethod
is useful when matching on several fields is considered better than having a good match on a single field. -
DISJUNCTION_MAX_REWRITE
BlendedTermQuery.DisjunctionMaxRewrite
instance with a tie-breaker of0.01
.
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Method Details
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equals
Description copied from class:Query
Override and implement query instance equivalence properly in a subclass. This is required so thatQueryCache
works properly.Typically a query will be equal to another only if it's an instance of the same class and its document-filtering properties are identical that other instance. Utility methods are provided for certain repetitive code.
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hashCode
public int hashCode()Description copied from class:Query
Override and implement query hash code properly in a subclass. This is required so thatQueryCache
works properly. -
toString
Description copied from class:Query
Prints a query to a string, withfield
assumed to be the default field and omitted. -
rewrite
Description copied from class:Query
Expert: called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.- Overrides:
rewrite
in classQuery
- Throws:
IOException
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visit
Description copied from class:Query
Recurse through the query tree, visiting any child queries
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