Class BlendedTermQuery
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
Nested ClassesModifier and TypeClassDescriptionstatic classA Builder forBlendedTermQuery.static classABlendedTermQuery.RewriteMethodthat creates aDisjunctionMaxQueryout of the sub queries.static classABlendedTermQuery.RewriteMethoddefines how queries for individual terms should be merged. -
Field Summary
FieldsModifier and TypeFieldDescriptionstatic final BlendedTermQuery.RewriteMethodABlendedTermQuery.RewriteMethodthat adds all sub queries to aBooleanQuery.static final BlendedTermQuery.RewriteMethodBlendedTermQuery.DisjunctionMaxRewriteinstance with a tie-breaker of0.01. -
Method Summary
Modifier and TypeMethodDescriptionbooleanOverride and implement query instance equivalence properly in a subclass.inthashCode()Override and implement query hash code properly in a subclass.final Queryrewrite(IndexSearcher indexSearcher) Expert: called to re-write queries into primitive queries.Prints a query to a string, withfieldassumed to be the default field and omitted.voidvisit(QueryVisitor visitor) Recurse through the query tree, visiting any child queries.Methods 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.RewriteMethodthat adds all sub queries to aBooleanQuery. ThisBlendedTermQuery.RewriteMethodis useful when matching on several fields is considered better than having a good match on a single field. -
DISJUNCTION_MAX_REWRITE
BlendedTermQuery.DisjunctionMaxRewriteinstance with a tie-breaker of0.01.
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Method Details
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equals
Description copied from class:QueryOverride and implement query instance equivalence properly in a subclass. This is required so thatQueryCacheworks 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 to those of the other instance. Utility methods are provided for certain repetitive code.
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hashCode
public int hashCode()Description copied from class:QueryOverride and implement query hash code properly in a subclass. This is required so thatQueryCacheworks properly. -
toString
Description copied from class:QueryPrints a query to a string, withfieldassumed to be the default field and omitted. -
rewrite
Description copied from class:QueryExpert: called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.Callers are expected to call
rewritemultiple times if necessary, until the rewritten query is the same as the original query.The rewrite process may be able to make use of IndexSearcher's executor and be executed in parallel if the executor is provided.
- Overrides:
rewritein classQuery- Throws:
IOException- See Also:
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visit
Description copied from class:QueryRecurse through the query tree, visiting any child queries.
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