Class MultiTermQuery
- All Implemented Interfaces:
Cloneable
- Direct Known Subclasses:
AutomatonQuery
,FuzzyQuery
,NumericRangeQuery
,PrefixQuery
,TermRangeQuery
Query
that matches documents
containing a subset of terms provided by a FilteredTermsEnum
enumeration.
This query cannot be used directly; you must subclass
it and define getTermsEnum(Terms,AttributeSource)
to provide a FilteredTermsEnum
that iterates through the terms to be
matched.
NOTE: if setRewriteMethod(org.apache.lucene.search.MultiTermQuery.RewriteMethod)
is either
CONSTANT_SCORE_BOOLEAN_QUERY_REWRITE
or SCORING_BOOLEAN_QUERY_REWRITE
, you may encounter a
BooleanQuery.TooManyClauses
exception during
searching, which happens when the number of terms to be
searched exceeds BooleanQuery.getMaxClauseCount()
. Setting setRewriteMethod(org.apache.lucene.search.MultiTermQuery.RewriteMethod)
to CONSTANT_SCORE_FILTER_REWRITE
prevents this.
The recommended rewrite method is CONSTANT_SCORE_AUTO_REWRITE_DEFAULT
: it doesn't spend CPU
computing unhelpful scores, and it tries to pick the most
performant rewrite method given the query. If you
need scoring (like FuzzyQuery
, use
MultiTermQuery.TopTermsScoringBooleanQueryRewrite
which uses
a priority queue to only collect competitive terms
and not hit this limitation.
Note that org.apache.lucene.queryparser.classic.QueryParser produces
MultiTermQueries using CONSTANT_SCORE_AUTO_REWRITE_DEFAULT
by default.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
A rewrite method that tries to pick the best constant-score rewrite method based on term and document counts from the query.static class
Abstract class that defines how the query is rewritten.static final class
A rewrite method that first translates each term intoBooleanClause.Occur.SHOULD
clause in a BooleanQuery, but the scores are only computed as the boost.static final class
A rewrite method that first translates each term intoBooleanClause.Occur.SHOULD
clause in a BooleanQuery, and keeps the scores as computed by the query. -
Field Summary
FieldsModifier and TypeFieldDescriptionstatic final MultiTermQuery.RewriteMethod
Read-only default instance ofMultiTermQuery.ConstantScoreAutoRewrite
, withConstantScoreAutoRewrite.setTermCountCutoff(int)
set toConstantScoreAutoRewrite.DEFAULT_TERM_COUNT_CUTOFF
andConstantScoreAutoRewrite.setDocCountPercent(double)
set toConstantScoreAutoRewrite.DEFAULT_DOC_COUNT_PERCENT
.static final MultiTermQuery.RewriteMethod
LikeSCORING_BOOLEAN_QUERY_REWRITE
except scores are not computed.static final MultiTermQuery.RewriteMethod
A rewrite method that first creates a private Filter, by visiting each term in sequence and marking all docs for that term.protected final String
protected MultiTermQuery.RewriteMethod
static final MultiTermQuery.RewriteMethod
A rewrite method that first translates each term intoBooleanClause.Occur.SHOULD
clause in a BooleanQuery, and keeps the scores as computed by the query. -
Constructor Summary
ConstructorsConstructorDescriptionMultiTermQuery
(String field) Constructs a query matching terms that cannot be represented with a single Term. -
Method Summary
Modifier and TypeMethodDescriptionboolean
final String
getField()
Returns the field name for this queryprotected final TermsEnum
getTermsEnum
(Terms terms) Convenience method, if no attributes are needed: This simply passes empty attributes and is equal to:getTermsEnum(terms, new AttributeSource())
protected abstract TermsEnum
getTermsEnum
(Terms terms, AttributeSource atts) Construct the enumeration to be used, expanding the pattern term.int
hashCode()
final Query
rewrite
(IndexReader reader) To rewrite to a simpler form, instead return a simpler enum fromgetTermsEnum(Terms, AttributeSource)
.void
Sets the rewrite method to be used when executing the query.Methods inherited from class org.apache.lucene.search.Query
clone, createWeight, extractTerms, getBoost, setBoost, toString, toString
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Field Details
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field
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rewriteMethod
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CONSTANT_SCORE_FILTER_REWRITE
A rewrite method that first creates a private Filter, by visiting each term in sequence and marking all docs for that term. Matching documents are assigned a constant score equal to the query's boost.This method is faster than the BooleanQuery rewrite methods when the number of matched terms or matched documents is non-trivial. Also, it will never hit an errant
BooleanQuery.TooManyClauses
exception. -
SCORING_BOOLEAN_QUERY_REWRITE
A rewrite method that first translates each term intoBooleanClause.Occur.SHOULD
clause in a BooleanQuery, and keeps the scores as computed by the query. Note that typically such scores are meaningless to the user, and require non-trivial CPU to compute, so it's almost always better to useCONSTANT_SCORE_AUTO_REWRITE_DEFAULT
instead.NOTE: This rewrite method will hit
BooleanQuery.TooManyClauses
if the number of terms exceedsBooleanQuery.getMaxClauseCount()
. -
CONSTANT_SCORE_BOOLEAN_QUERY_REWRITE
LikeSCORING_BOOLEAN_QUERY_REWRITE
except scores are not computed. Instead, each matching document receives a constant score equal to the query's boost.NOTE: This rewrite method will hit
BooleanQuery.TooManyClauses
if the number of terms exceedsBooleanQuery.getMaxClauseCount()
. -
CONSTANT_SCORE_AUTO_REWRITE_DEFAULT
Read-only default instance ofMultiTermQuery.ConstantScoreAutoRewrite
, withConstantScoreAutoRewrite.setTermCountCutoff(int)
set toConstantScoreAutoRewrite.DEFAULT_TERM_COUNT_CUTOFF
andConstantScoreAutoRewrite.setDocCountPercent(double)
set toConstantScoreAutoRewrite.DEFAULT_DOC_COUNT_PERCENT
. Note that you cannot alter the configuration of this instance; you'll need to create a private instance instead.
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Constructor Details
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MultiTermQuery
Constructs a query matching terms that cannot be represented with a single Term.
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Method Details
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getField
Returns the field name for this query -
getTermsEnum
Construct the enumeration to be used, expanding the pattern term. This method should only be called if the field exists (ie, implementations can assume the field does exist). This method should not return null (should instead returnTermsEnum.EMPTY
if no terms match). The TermsEnum must already be positioned to the first matching term. The givenAttributeSource
is passed by theMultiTermQuery.RewriteMethod
to provide attributes, the rewrite method uses to inform about e.g. maximum competitive boosts. This is currently only used byTopTermsRewrite
- Throws:
IOException
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getTermsEnum
Convenience method, if no attributes are needed: This simply passes empty attributes and is equal to:getTermsEnum(terms, new AttributeSource())
- Throws:
IOException
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rewrite
To rewrite to a simpler form, instead return a simpler enum fromgetTermsEnum(Terms, AttributeSource)
. For example, to rewrite to a single term, return aSingleTermsEnum
- Overrides:
rewrite
in classQuery
- Throws:
IOException
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getRewriteMethod
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setRewriteMethod
Sets the rewrite method to be used when executing the query. You can use one of the four core methods, or implement your own subclass ofMultiTermQuery.RewriteMethod
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hashCode
public int hashCode() -
equals
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